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Scuba Forum / General / February 2010Newbie
I just got my PADI OW, and added a night, wreck and deep (110') dives, and others for a total of 12 dives. (San Andres, Columbia). My key issue is that I'm 6'2" and broad/deep chested and go through air like crazy even when I do my level best to be slow and calm. For my deep dive, the instructor dragged down an extra bottle/regulator set. When I got to 600 psi, I took and carried the extra under one arm for the rest of the dive... not how I'd like to operate in the future. (Even on a shallower off the rocks dive, I ended up going to my SO (who is thin) and using her air for nearly 10 minutes before going to the surface on my own air - 200 psi left - She had 1300 left even with me stealing her air). On another dive, there I was at 20 ft with 0 air left, I could suck in a few last breaths as I slowly made my way up. Now starting to look at buying gear (all I have are fins, mask and snorkel, though my 30 year old mask needs replacing, leaks too much water during dives). I've found a BCD that takes one or two tanks, so I assume their are regulars with a cross manifold? (whatever it's called). Can this be 'mix and match'? eg: dive with 1 or 2 bottles as needed?  Signaturegmail originated posts are filtered due to spam. > I just got my PADI OW, and added a night, wreck and deep (110') dives, > and others for a total of 12 dives. (San Andres, Columbia). [quoted text clipped - 17 lines] > regulars with a cross manifold? (whatever it's called). Can this be > 'mix and match'? eg: dive with 1 or 2 bottles as needed? I don't do doubles, but few who do seem to mix and match. A pony bottle (30-40 cubic foot bottle carried auxiliary) is more easily switched out, but still has most of the extra cost (2 complete regulators). Doubles and the associated hardware are a lot of money which you could better spend on going places and diving more. If you are going to buy tanks you can buy single tanks with larger capacity (100 or 120 cubic feet instead of the 77 in a typical "80"), but the main thing you need is more time underwater, perhaps more thermal insulation - a thicker and/or better fitting suit, perhaps a hood. Being cold burns air. So does fiddling with a leaky mask. Being large does not inherently make you suck a lot of air. Being inefficient does, but efficiency and actual calm takes time. You can get all bound up in a cycle of trying to be calm (as a deliberate, thunk act) and not be calm at all because of it. More time diving is the cure. If you are still burning air like mad at 100 dives, then you might be at a reasonable point to consider tech hardware (which doubles are) as a solution. Twelve is a bit early to jump on that, IMHO. SignatureCats, coffee, chocolate...vices to live by On Jan 28, 2:24 pm, Ecnerwal <MyNameForw...@ReplaceWithMyVices.Com.invalid> wrote: > Being large does not inherently make you suck a lot of air. Being > inefficient does, but efficiency and actual calm takes time. You can get > all bound up in a cycle of trying to be calm (as a deliberate, thunk > act) and not be calm at all because of it. More time diving is the cure. "At rest, we breathe approximately 15 times per minute, with a volume of around 0.5 litres (producing a ‘minute ventilation’ of 7.5 litres per minute [15 x 0.5]). The volume of each breath (tidal volume) depends on body size and metabolic rate (bigger people have larger lungs and take larger breaths, they also require more energy and oxygen to support their metabolism). "During heavy exercise, breathing frequency rises to around 40 to 50 breaths per minute. In ‘the man in the street’, tidal volume rises to around 3 to 4 litres (minute ventilation = 120 to 160 litres per minute), but in Olympic class male endurance athletes, tidal volume can be over 5 litres, resulting in minute ventilations of 250 to 300 litres per minute." http://ironman.com/training/sponsors/the-first-of-a-series-of-articles-from-powe rbreathe-focuses-on-breathing-issues-in-swimming-cycling So, being larger does make one "suck up" more air. Surprisingly, those with better fitness levels will have a higher tidal volume and therefore "suck up" more air when exercising (i.e. kicking against current) than unfit persons. Therefore, the highly fit large person will, on average, suck down a tank much faster than a little couch potato. (Or at least that's what I always tell the little couch potatoes when they brag about having so much air left after a dive when I've run my gauge near empty.) > On Jan 28, 2:24 pm, Ecnerwal > <MyNameForw...@ReplaceWithMyVices.Com.invalid> wrote: [quoted text clipped - 28 lines] > potatoes when they brag about having so much air left after a dive > when I've run my gauge near empty.) It makes sense to me. I can't say I'm at all athletic nor optimally fit (and I am carrying a few more pounds than I like), though I've been a swimmer all my life. Scuba's a recent thing and I hope to dive many times. It's a very serene and beautiful thing. Question: when swimming against an oscillating current (reef with surges), is it better to let the current push you back and then swim strongly when it ebbs, or better to hold position (swim against) and then let it carry you w/o effort on the ebb? Signaturegmail originated posts are filtered due to spam. On Jan 28, 3:36 pm, Alan Browne <alan.bro...@FreelunchVideotron.ca> wrote: > > So, being larger does make one "suck up" more air. Surprisingly, > > those with better fitness levels will have a higher tidal volume and [quoted text clipped - 9 lines] > I can't say I'm at all athletic nor optimally fit (and I am carrying a > few more pounds than I like), though I've been a swimmer all my life. But that's my excuse, not yours yet. I'm perfectly comfortable in the water and have excellent breathing and finning technique after 600+ dives, but occasionally need to shut little people down because they think they're so "good" on air. You, however, still have to get over the hump. Somewhere around 25-50 dives or more, but in almost all cases less than 100, divers "learn" to breathe properly underwater. Your air consumption will drop dramatically no matter your size, and you can start to use breathing "tricks" when appropriate, such as using your inhalation/exhalation to change your depth, or holding your breath (gasp, no!) at appropriate times in order to maintain exact depth (necessary for taking better photos). > Scuba's a recent thing and I hope to dive many times. It's a very > serene and beautiful thing. Make sure you keep that to yourself, telling everyone else how scary it is. We don't want it getting too crowded underwater :) > Question: when swimming against an oscillating current (reef with > surges), is it better to let the current push you back and then swim > strongly when it ebbs, or better to hold position (swim against) and > then let it carry you w/o effort on the ebb? Uh, neither. Better to hold position (swim against, if not too strong and most surge-induced such oscillation currents rarely are), then fin lightly when it's in your favor (unless you need the exercise and want to go REAL fast, but then you miss a lot of stuff). That's from the aspect of a slow-going diver who needs time to search for critters and take their pictures. Obviously if you're a Navy Seal intent on placing some explosives according to a narrow time frame, then swim your a.s off no matter what, but they probably cover that in training. There is nothing more frustrating to me underwater than some dive op where the DM/guide motions me to "hurry up". When that happens in a place like Cozumel with its strong currents and drift diving, I simply slow down until the DM disppears from sight, then enjoy the rest of the dive at my pace. Us big guys have the advantage over little Cozumelian DM's - simply increase resistance by putting maximum surface area against the current, i.e. stand up straight. Ducking behind coral bommies to escape the current helps with the especially pernicious DMs. (Actually, camera failure underwater is even more frustrating; better to have a working camera underwater following a fast DM, then to be carrying a worthless piece of hardware at your own pace.) > On Jan 28, 3:36 pm, Alan Browne<alan.bro...@FreelunchVideotron.ca> > wrote: [quoted text clipped - 24 lines] > breath (gasp, no!) at appropriate times in order to maintain exact > depth (necessary for taking better photos). I quickly got the hang of using breathing for depth control, eg, swimming very close to the bottom and then climbing over a bump or plant with a deep inhalation. This was on later dives once I'd worked out the proper amount of Pb to hang on my waist and not start climbing as the tank emptied. I haven't tried u-w photography yet (other than a cheap Kodak re-cyclable) (will definitely next time), but I'm sensitive to how still one should be. (I am a photographer). >> Scuba's a recent thing and I hope to dive many times. It's a very >> serene and beautiful thing. > > Make sure you keep that to yourself, telling everyone else how scary > it is. We don't want it getting too crowded underwater :) I met a Swiss pair there who had dived in the Red Sea several times saying that at some sites there would be 40 divers per boat and many boats per site. No thanks. >> Question: when swimming against an oscillating current (reef with >> surges), is it better to let the current push you back and then swim [quoted text clipped - 9 lines] > placing some explosives according to a narrow time frame, then swim > your a.s off no matter what, but they probably cover that in training. ;-) > There is nothing more frustrating to me underwater than some dive op > where the DM/guide motions me to "hurry up". When that happens in a [quoted text clipped - 8 lines] > fast DM, then to be carrying a worthless piece of hardware at your own > pace.) I'll keep that in mind. The idea of drift diving is appealing to me but my SO wants nothing to do with it. I couldn't get her out night diving either. On one of our dives (the deep one) we came up the wall and onto the reef at about 25 feet. We swam parallel to the wall looking for the buoy anchor chain. (There had been a good blow a couple days prior and the buoy had been lost so we dove off the boat without anchoring). During that swim south, we were tossed left and right about 10 ft. But it felt cool, just let it happen. Start to breathe in just before going right (rising coral), breathe out just before going left (towards the wall and falling coral. That worked great. Safety stop at 15 ft for 3, a little further out over the deeper water, inflate a marker and let it up to call in the boat. Problem there was one of the divers (very experienced and also from here in Quebec) got seasick in the ebb and flow during the stop ... he was the time keeper for the safety stop ... as soon as he got in the boat (did I mention the 10 ft. swells?) he puked, but a gentleman, over the side and downwind. He made the next dive though he looked a little green in the boat on the way there. Signaturegmail originated posts are filtered due to spam. On Jan 28, 4:53 pm, Alan Browne <alan.bro...@FreelunchVideotron.ca> wrote: > I haven't tried u-w photography yet (other than a cheap Kodak > re-cyclable) (will definitely next time), but I'm sensitive to how still > one should be. (I am a photographer). You might want to hold off on serious underwater photography until you get the basics down pat. Focusing (literally and figuratively) on a complex task such as a manually adjusted D-SLR is better saved for when you have a keen awareness of your surroundings (in order to protect them and you) and your equipment/gauges/air consumption rate. You also want to make sure you're with a very competent buddy since good buddy skills go out the window when you're trying to take serious pictures. That's really biased toward macro photography, my favorite type. Wide- angle photography is far more tolerant of movement and requires less concentration - it's more about getting the exposure right and all about composition. Here's one of my proudest accomplishments, though you can't really tell from looking at it. I shot this tiny nudibranch, less than 1 cm in length, in extreme surge off Orange Beach, Peleliu Island, Palau. Getting that close required manually focusing my 105mm macro lens, difficult enough even in calm conditions (plus I also manually adjust my exposure and shutter speed and individually control two strobes). The trick is to let the surge bring you into focus, then snap the photo at the right instant. http://picasaweb.google.com/Mossman.Photos/Palau#5180250055567955810 It took 7 shots to get it right. > I met a Swiss pair there who had dived in the Red Sea several times > saying that at some sites there would be 40 divers per boat and many > boats per site. No thanks. Some places are remote enough that you won't see other divers around. Week-long+ liveaboards or multi-day arduous travel are often necessary for this. There are short-term (2-3 day) liveaboards that go to close- in sites on the Great Barrier Reef, Red Sea, or Similan Islands bringing dozens of divers to sites already teeming with divers. Not my cup of tea either. The term for these sort of vessels is "cattleboat". (The term also applies to day-boats that might hold 24 or more divers, versus smaller boats that hold 6 or less, or "six pacs" - some apply the cattleboat term to 12-pack boats, while others are OK with that number). > I'll keep that in mind. The idea of drift diving is appealing to me but > my SO wants nothing to do with it. I couldn't get her out night diving > either. Patience, patience. She shouldn't have a problem with drift diving, at least in slow currents, as long as you're following a guide. It's the same as going with the current then kicking back against the current, except that you skip the latter part. Having the boat find you is usually much easier than you trying to find the boat. As for night diving, the trick that worked with my SO was doing a dusk shore dive (we did "Turtle Farm" on Grand Cayman). She had freaked during her first boat night attempt and no wonder, you're faced with jumping into black water. But when we started in blue water right before sunset when she could still see, then let it gradually get dark, she quickly adapted and now she loves to night dive more than me. > On one of our dives (the deep one) we came up the wall and onto the reef > at about 25 feet. We swam parallel to the wall looking for the buoy [quoted text clipped - 15 lines] > side and downwind. He made the next dive though he looked a little > green in the boat on the way there. Yah, puke and diving definitely go together, just like puke and heavy drinking :) Besides occasional seasickness, which I usually get on the boat and it goes away as soon as I jump in the water, I get the occasional bout of alternobaric vertigo (caused by unequal ear clearing) that can leave me nauseous and puking on the surface. I've also gotten seasick from safety stop surge from time to time, but only when badly hungover. I find it much more gratifying to watch others get sick than to be one everyone else is watching lose his lunch. Did your Quebecois ami have a rough night before the dive? > On Jan 28, 4:53 pm, Alan Browne<alan.bro...@FreelunchVideotron.ca> > wrote: [quoted text clipped - 44 lines] > pacs" - some apply the cattleboat term to 12-pack boats, while others > are OK with that number). I'd be happy with up to, say, 10 divers in the water if the area wasn't too small. The boat we had could accommodate 24 divers (I would guess) but the most in there at one time was about 7 or 8. >> I'll keep that in mind. The idea of drift diving is appealing to me but >> my SO wants nothing to do with it. I couldn't get her out night diving [quoted text clipped - 13 lines] > dark, she quickly adapted and now she loves to night dive more than > me. I think next time I'll have more success. The timetable, alas, was set by the instructor. I thought the night dive was great. Esp. with all our light off (for a minute or so). IAC, she was ill (food poisoning) while she waited for us on the rocks. Spent the next day in bed (so I went diving, of course!). >> On one of our dives (the deep one) we came up the wall and onto the reef >> at about 25 feet. We swam parallel to the wall looking for the buoy [quoted text clipped - 21 lines] > occasional bout of alternobaric vertigo (caused by unequal ear > clearing) that can leave me nauseous and puking on the surface. I had a reverse block on the way up from the deep dive, but it cleared pretty quick (less than a minute) by just going down a few feet and massaging under my ears. No vertigo. > I've > also gotten seasick from safety stop surge from time to time, but only > when badly hungover. I find it much more gratifying to watch others > get sick than to be one everyone else is watching lose his lunch. Did > your Quebecois ami have a rough night before the dive? He was pretty straight laced. (Guy was about 35 and came to the island with his mother, just to set the scene right.) He made one dive outing (2 dives) but brought all his gear down to the island. I mentioned the night dive to him and he said he'd done all the diving he would do on that trip. I saw him at the bar once. The Swiss couple practically held the bar in place - but were not heavy drinkers - just continuous). He mentioned on the way to the dive that he was feeling seasick - so nobody was surprised. (My SO took Gravol on a couple of the longer boat rides out - she had felt off on one earlier trip, but held up). Signaturegmail originated posts are filtered due to spam. Hi Greg, > But that's my excuse, not yours yet. I'm perfectly comfortable in the > water and have excellent breathing and finning technique after 600+ > dives, but occasionally need to shut little people down because they > think they're so "good" on air. Naaa, you don`t. The brain and liver are the biggest oxigen consumers in your body. Women have less brain than men in average and the braggers have less too. That´s the only reason for their poor air consumption. ;-) lg Joerg SignatureDie neuen Knips-Fotos aus dem Urlaub: http://www.notabstieg.de/maledives-4-2009/index.html http://www.grabmalkultur.de > Hi Greg, > [quoted text clipped - 6 lines] > your body. Women have less brain than men in average and the braggers > have less too. That´s the only reason for their poor air consumption. I'll have to stop thinking when diving, I guess. ;) Signaturegmail originated posts are filtered due to spam. > Naaa, you don`t. The brain and liver are the biggest oxigen consumers in > your body. Women have less brain than men in average and the braggers > have less too. That´s the only reason for their poor air consumption. > > ;-) By that theory, since I've destroyed so many brain and liver cells from alcohol consumption, I should be great on air too :) On Thu, 28 Jan 2010 16:10:28 -0800 (PST), Greg Mossman >There is nothing more frustrating to me underwater than some dive op >where the DM/guide motions me to "hurry up". When that happens in a >place like Cozumel with its strong currents and drift diving, I simply >slow down until the DM disppears from sight, then enjoy the rest of >the dive at my pace. I prefer to come back on the same boat I went out on. > On Thu, 28 Jan 2010 16:10:28 -0800 (PST), Greg Mossman > [quoted text clipped - 5 lines] > > I prefer to come back on the same boat I went out on. Why? If they don't take you back, you should be entitled to at least a partial refund. >Why? If they don't take you back, you should be entitled to at least >a partial refund. On one of my trips to the Caymans, the dive briefing mentioned that if you got on the wrong boat, it would cost the DM a case of beer to get you back, and you would be expected to re-imburse him with interest. > On Sat, 30 Jan 2010 08:03:50 -0800 (PST), Greg Mossman > [quoted text clipped - 5 lines] > you got on the wrong boat, it would cost the DM a case of beer to get > you back, and you would be expected to re-imburse him with interest. Normally I'd just take that out of the DM's tip, but in the Caymans you could buy a new boat for the cost of a case of beer. That's even more a reason to dive in Cozumel where the beer is much cheaper. > > On one of my trips to the Caymans, the dive briefing mentioned that if > > you got on the wrong boat, it would cost the DM a case of beer to get [quoted text clipped - 3 lines] > you could buy a new boat for the cost of a case of beer. That's even > more a reason to dive in Cozumel where the beer is much cheaper. Sounds like you guys both don't know where to shop in the Caymans. :-) The "toll" used to be one sixpack, although to be nice, one might double that. And last fall, I think I paid CI$50 for a case of Stella, which is roughly US$16/sixpack. -hh > On Thu, 28 Jan 2010 16:10:28 -0800 (PST), Greg Mossman >> There is nothing more frustrating to me underwater than some dive op [quoted text clipped - 4 lines] > > I prefer to come back on the same boat I went out on. Reminds me of our boat captain (who I later labeled "Gaucho da Mar" (Sea Cowboy)). At anchor, once all the divers were in the water he'd dive in to snorkel. On one dive he headed straight to a competing co. DM and grabbed his (dangling/unsecured) octo for free air... on a later dive he was given the universal sign to bugger off. Signaturegmail originated posts are filtered due to spam. > On Thu, 28 Jan 2010 16:10:28 -0800 (PST), Greg Mossman >> There is nothing more frustrating to me underwater than some dive op [quoted text clipped - 4 lines] > > I prefer to come back on the same boat I went out on. That way, you don't have to pay two charter fees (grin). -- John Eells [Default] Thus spake Greg Mossman <mossman@qnet.com>: >On Jan 28, 3:36 pm, Alan Browne <alan.bro...@FreelunchVideotron.ca> >wrote: <snip> >> Scuba's a recent thing and I hope to dive many times. It's a very >> serene and beautiful thing. > >Make sure you keep that to yourself, telling everyone else how scary >it is. We don't want it getting too crowded underwater :) "Aren't you afraid of the sharks?" "Oh hell yeah, we keep as far away as possible" (while looking at the shots I have of a bull, althoug at a respectful distance) >> Question: when swimming against an oscillating current (reef with >> surges), is it better to let the current push you back and then swim [quoted text clipped - 22 lines] >fast DM, then to be carrying a worthless piece of hardware at your own >pace.) DM at Scuba Club was the same way with us the first day, then just said "find me when you done, right?" And got pissed when he ran out of air before I did. Signature- dillon I am not invalid I love my country, It's my government I fear. Hey, turnabout's fair play. On Thu, 28 Jan 2010 18:36:37 -0500, Alan Browne >Question: when swimming against an oscillating current (reef with >surges), is it better to let the current push you back and then swim >strongly when it ebbs, or better to hold position (swim against) and >then let it carry you w/o effort on the ebb? Depends on whether you want to go slow or fast. > On Thu, 28 Jan 2010 18:36:37 -0500, Alan Browne >> Question: when swimming against an oscillating current (reef with [quoted text clipped - 3 lines] > > Depends on whether you want to go slow or fast. Given the qualified answer could you expand on that? Signaturegmail originated posts are filtered due to spam. >Given the qualified answer could you expand on that? If you want to go fast, kick when the current is with you and rest when it's against you. If you want to go slow, kick to hold your position when it's against you and don't kick when it's with you. [Default] Thus spake Greg Mossman <mossman@qnet.com>: >On Jan 28, 2:24 pm, Ecnerwal ><MyNameForw...@ReplaceWithMyVices.Com.invalid> wrote: [quoted text clipped - 28 lines] >potatoes when they brag about having so much air left after a dive >when I've run my gauge near empty.) In 5 semester, I took according to my log, 1800 chest xrays (out of about 4000 total). Big guys have short, broad lung. Little old ladies look like the have lungs that go from the ears to the hips (at which point eveybody is supposed to laugh). But they're all about the same volume. Big guys without efficient systems have a harder problem getting the oxygen into their system. Which is why a 250 pound pro basketball player can go for a full game (yeah, commercial breaks) while a 250 pound marshmallow is gasping after 5 minutes. It's why I, at 165, ran out of steam waling up a really steep trail, while the two 200 pound Marines ran up the sucker. Signature- dillon I am not invalid I love my country, It's my government I fear. Hey, turnabout's fair play. > On another dive, there I was at 20 ft with 0 air > left, I could suck in a few last breaths as I slowly made my way up. Forgot to address this point in my first reply - you, only you, and nobody but you are responsible for checking your air before and during the dive, and making sure that you (and your buddy) come up in time to have air left. Being out of air at 20 feet doesn't "just happen" (and where was your buddy, with her octopus and lower air consumption rate?) If your instructor failed to make you a self-reliant, self-aware diver, your instructor did you wrong, but since you are certified, it's now your problem to make yourself self-responsible and self-aware, since that is what certification is supposed to indicate. This is a common failing of some (not all) resort-area tropical dive "instructors." In the minor fiddles department, when you and your buddy board a dive boat, while you are checking that all of your tanks for the trip have air and setting up your gear before you leave the dock, note the pressure in them all, and put the higher-pressure ones on your side of the area (there's nearly always a little variation in the fills.) SignatureCats, coffee, chocolate...vices to live by >> On another dive, there I was at 20 ft with 0 air >> left, I could suck in a few last breaths as I slowly made my way up. [quoted text clipped - 4 lines] > have air left. Being out of air at 20 feet doesn't "just happen" (and > where was your buddy, with her octopus and lower air consumption rate?) I was fully aware of my air state as I had the pressure guage in front of my face during the climb-swim to the boat. No panic, worry or anticipation over it and when it ran out it was no surprise at all. That's why I was at 20 feet and climbing. I just leisurely swam straight up, slower than my bubbles, turning to look for surface obstacles. At the surface there was some pressure left for the BCD and I added to that through the low pressure tube. The net consequence of all that was I had to swim a hundred meters to the boat on the surface and I learned more about what to expect when pressure is low. I'd prefer not to do this "regularly" of course, but this was "school" time in any case. On one of the instruction dives where I had to recover a lost 2nd stage, I actually couldn't find it (30 ft). After trying all the techniques (rolling all the way right, using my left hand to tilt/lift the tank, finding the first stage and trying to trace the 2nd ... and failing (Lord knows why)) finally, without panic I took backup regulator and used it. Immediately after that failed attempt, I did it again with no problem. Not really sure at all why I couldn't do it the first time. The instructor said later he was more impressed by that slow process and then finally resorting to the backup than if I'd actually done it right in the first place. This raises a question, though. Is it feasible to go from 60 feet to the surface on one breath of air? That is to say, while continuously exhaling, slowly, rise right to the surface over a period of one minute? Would one feel that they were "out of oxygen?" (For the sake of this question, let's assume that the dive was no deeper than 60 feet). > If your instructor failed to make you a self-reliant, self-aware diver, > your instructor did you wrong, but since you are certified, it's now > your problem to make yourself self-responsible and self-aware, since > that is what certification is supposed to indicate. This is a common > failing of some (not all) resort-area tropical dive "instructors." He was very aware of my high rate of consumption and gave me the check air signal quite a lot until he was satisfied I knew my state (eg: he'd ask and I'd have a ready reply as I'd recently checked). To be sure, I've become quite sensitive to status. > In the minor fiddles department, when you and your buddy board a dive > boat, while you are checking that all of your tanks for the trip have > air and setting up your gear before you leave the dock, note the > pressure in them all, and put the higher-pressure ones on your side of > the area (there's nearly always a little variation in the fills.) I was doing that from about the 4th dive as I realized what an air pig I am. Most of the bottles were right at 3k on each dive bud discovered a couple times they were at 2800 and switched to 3k bottles. Thx, Alan Signaturegmail originated posts are filtered due to spam. On Jan 28, 3:30 pm, Alan Browne <alan.bro...@FreelunchVideotron.ca> wrote: > > where was your buddy, with her octopus and lower air consumption rate?) > > I was fully aware of my air state as I had the pressure guage in front > of my face during the climb-swim to the boat. No panic, worry or > anticipation over it and when it ran out it was no surprise at all. We're not worried about you, we're worried about the equipment. When you eliminate the positive pressure, i.e. no more air, then you allow backflow of sea water into the regulator's first and second stages and potentially into the tank itself. That really pisses off dive ops if you're using their rental gear. > That's why I was at 20 feet and climbing. I just leisurely swam > straight up, slower than my bubbles, turning to look for surface [quoted text clipped - 4 lines] > prefer not to do this "regularly" of course, but this was "school" time > in any case. What doesn't kill you makes you stronger. Some people swear by the need to maintain some air at the surface, because they don't like ocean swells. But if you're comfortable and don't need to breathe through a regulator at the surface, you still need to consider the immediate need to re-descend, especially in areas with boat traffic. If you surface and a boat is motoring down on you at high speed, your immediate instinct will be to let the air back out of your BC and descend quickly. You'll really be appreciating even a drop of air left in your tank at that point. > On one of the instruction dives where I had to recover a lost 2nd stage, > I actually couldn't find it (30 ft). After trying all the techniques [quoted text clipped - 6 lines] > then finally resorting to the backup than if I'd actually done it right > in the first place. More advanced classes, and certainly tech classes, will actually train you like that. It's good that you "trained" yourself, since safety conscious certification agencies don't like to let the instructors actually hide stuff from you during open-water training nowadays. > This raises a question, though. Is it feasible to go from 60 feet to > the surface on one breath of air? That is to say, while continuously > exhaling, slowly, rise right to the surface over a period of one minute? > Would one feel that they were "out of oxygen?" If you're a free diver that can easily hold his/her breath for 5 minutes? Of course not. For the rest of us, you'll be fighting an instinct to breathe, but you'll still have plenty of oxygen. It's all in your head. That said, there's no guarantee that you'll have that "one breath of air" left. If your air source conks out right after exhalation, you're screwed! > On Jan 28, 3:30 pm, Alan Browne<alan.bro...@FreelunchVideotron.ca> > wrote: [quoted text clipped - 10 lines] > potentially into the tank itself. That really pisses off dive ops if > you're using their rental gear. You're right of course. I did mention this to them and said sorry in the same breath. They didn't seem too upset. They didn't "flag" the bottle either - which makes one wonder. >> That's why I was at 20 feet and climbing. I just leisurely swam >> straight up, slower than my bubbles, turning to look for surface [quoted text clipped - 14 lines] > descend quickly. You'll really be appreciating even a drop of air > left in your tank at that point. Excellent point. That side (west) of the island had very little boat traffic (east side is very heavy). But you're right, it would be good to avoid boats, esp. as I surfaced a good way away from the dive boat. I'm quite happy to snorkel (been doing that for a long time) when on the surface. Actually, the boat captain didn't like me much as after I got all my gear in the boat, I'd often dive right back in for a snorkel (and piss call) waiting for the others to arrive. He liked to have all his ducks sitting on the bench. Snorkeling to 20 feet isn't as easy as it was 20 years ago though... >> On one of the instruction dives where I had to recover a lost 2nd stage, >> I actually couldn't find it (30 ft). After trying all the techniques [quoted text clipped - 11 lines] > conscious certification agencies don't like to let the instructors > actually hide stuff from you during open-water training nowadays. Opportunity knocked. It's not that I'm Mr. Ice, but as I was trying to find the primary at some point I saw the yellow spare down on the clip. At some point I said "screw it!" and took that. >> This raises a question, though. Is it feasible to go from 60 feet to >> the surface on one breath of air? That is to say, while continuously [quoted text clipped - 7 lines] > "one breath of air" left. If your air source conks out right after > exhalation, you're screwed! I get that. (On one submersion I was breathing from my snorkel when I bled the BCD. That was really rude). But does equipment "do that"? eg: just fail in one go? Are there stats? On some dive in the future, under well considered conditions, I'd like to try a one breath assent from 30, then 45 then 60 feet. There are more interesting things to do, of course, but that's one for the "try it" jar. Signaturegmail originated posts are filtered due to spam. On Jan 28, 5:11 pm, Alan Browne <alan.bro...@FreelunchVideotron.ca> wrote: > You're right of course. I did mention this to them and said sorry in > the same breath. They didn't seem too upset. They didn't "flag" the > bottle either - which makes one wonder. Hey, it's Colombia :) Third-world dive practices often vary from the first-world agency dictates. The thirder the world, the scarier the dive op. > I'm quite happy to snorkel (been doing that for a long time) when on the > surface. Actually, the boat captain didn't like me much as after I got > all my gear in the boat, I'd often dive right back in for a snorkel (and > piss call) waiting for the others to arrive. He liked to have all his > ducks sitting on the bench. Snorkeling to 20 feet isn't as easy as it > was 20 years ago though... It's also not as safe, now that you're a diver. Don't forget that right after the dive, you still have plenty of residual nitrogen left inside your tissues, just (presumably) not enough to cause any decompression sickness at a normal rate of offgassing. However, repetitive free dives post-scuba have been shown to shake up the normal offgassing process enough to cause problems. If you want to snorkel after a dive, stay on the surface. > I get that. (On one submersion I was breathing from my snorkel when I > bled the BCD. That was really rude). But does equipment "do that"? > eg: just fail in one go? Are there stats? No, well-maintained equipment will rarely fail and when/if it does, most regulators will fail "open", i.e. they'll free-flow instead of cutting off the air supply. Free-flows are messy and noisy, but they won't keep you from breathing normally long enough to maintain a slow ascent back to the surface when you abort your dive. However, there are some regs, a few Poseidons that I can think of and probably some others, that will fail "closed" and make you wish you stayed within arm's length of your buddy like they told you in class. What's statistically more likely, at least according to the statistics, is inadvertently running out of air. That's plain stupidity, since everyone has a gauge (or should be smart enough to abort when the gauge fails), so those victims don't garner much sympathy. Not that I haven't done a few gaugeless dives out of what I considered "necessity" (i.e., I needed to dive!), but only after assuring myself that the tank was full, knowing my air consumption intimately, sticking relatively close to a buddy, and staying shallower than 30'. Don't try this at home :) > On some dive in the future, under well considered conditions, I'd like > to try a one breath assent from 30, then 45 then 60 feet. There are > more interesting things to do, of course, but that's one for the "try > it" jar. Just keep exhaling as you go, keep the ascent slow, and make sure you try it at the beginning of a dive day, before you've accumulated too much nitrogen and a too-rapid ascent becomes a real issue. > On Jan 28, 5:11 pm, Alan Browne<alan.bro...@FreelunchVideotron.ca> > wrote: [quoted text clipped - 21 lines] > normal offgassing process enough to cause problems. If you want to > snorkel after a dive, stay on the surface. oh. I would have though it's zero sum since I'm taking "surface air" with me, not 'pressed. >> I get that. (On one submersion I was breathing from my snorkel when I >> bled the BCD. That was really rude). But does equipment "do that"? [quoted text clipped - 8 lines] > others, that will fail "closed" and make you wish you stayed within > arm's length of your buddy like they told you in class. Now that you bring up my other bad habit... > What's statistically more likely, at least according to the > statistics, is inadvertently running out of air. That's plain > stupidity, since everyone has a gauge (or should be smart enough to > abort when the gauge fails), so those victims don't garner much > sympathy. That I can manage, but I may have PO'd buddies as I signal end-of-dive earlier than they're ready. > Not that I haven't done a few gaugeless dives out of what I considered > "necessity" (i.e., I needed to dive!), but only after assuring myself [quoted text clipped - 10 lines] > try it at the beginning of a dive day, before you've accumulated too > much nitrogen and a too-rapid ascent becomes a real issue. Certainly - not all on the same day, or even consecutive days, either! Signaturegmail originated posts are filtered due to spam. <snip> >>> I'm quite happy to snorkel (been doing that for a long time) when on the >>> surface. Actually, the boat captain didn't like me much as after I got >>> all my gear in the boat, I'd often dive right back in for a snorkel (and >>> piss call) waiting for the others to arrive. He liked to have all his >>> ducks sitting on the bench. Snorkeling to 20 feet isn't as easy as it >>> was 20 years ago though... <snip> > oh. I would have though it's zero sum since I'm taking "surface air" with > me, not 'pressed. Nope. You still have nitrogen, offgassing. Freediving down to 20' adds pressure which is not being equalized because you're not breathing. Ascending again will release the pressure and if its faster than the 30 ft will release the pressure quickly allowing bubbles to form. Freedivers have suffered from DCS just because of repetitive dives. It's rare, but can happen. Dennis <snip> Dennis > <snip> >>> [quoted text clipped - 20 lines] > Freedivers have suffered from DCS just because of repetitive dives. It's > rare, but can happen. Thx. Signaturegmail originated posts are filtered due to spam. >oh. I would have though it's zero sum since I'm taking "surface air" >with me, not 'pressed. In 1996 when I was certified, PADI, NAUI and DAN all advised against snorkeling after or between dives. I don't think that has changed. The physics makes it NOT a zero sum. While you are not absorbing new nitrogen on your snorkel dives, you still have more nitrogen in your tissues than you should have for normal surface pressure. Diving to 20 feet with a nitrogen load from a scuba dive and then a rapid ascent can get you bent. You are also not off-gassing as rapidly as the tables are designed or your computer calculates so your SIT is not what you think it is and your computer is lying to you on your next dive and not in a good way. Your nitrogen load is not what the clock time is telling you and you have no way to calculate what it really is. Granted, the tables and computers are "conservative" but do you really want to bet your life or nervous system on the margins? Unless you have a bottle of water on your snorkel you are also not re-hydrating during your SIT and dehydration has a strong influence on your blood chemistry and your off-gassing rate. Take the swim, stay on the surface, get back in the boat and take your hydration. Pee on the ascent and avoid the extra swim altogether. Just a few more comments - what the heck, it's actual scuba, which seems to have gone missing from rec.scuba since the last time I was reading it, mostly. As others have mentioned, and as the instruction material should have (but they like to dumb it down more and more) snorkeling is not a great practice for surface intervals. Snorkeling by which you actually mean free diving is a very bad idea - even surface snorkeling is not quite as effective at degassing as being on the surface breathing - the length of the tube makes respiration somewhat inefficient. Also, it does not help thermal management - even warm water is cold, barring a thermal spring (and what a sucky dive that was - amusing, but sucky) Do larger people use slightly more air - yes. Is that your primary air consumption problem at 12 dives - almost certainly not. The difference between large and small folk at the same level of experience is much less than the difference between experienced and inexperienced folk. Was diving at the beginning of the month, there was a guy on the boat of similar size and age, shallow water (25-30 feet) 1 hour limit requested by boat. He seemed to be in pretty good order, but was coming up with 250-300 lbs several minutes before my wife and I were getting out after the hour with 750-1500 lbs. Coincidentally, those were dives 11 & 12 for him. He'll get better, and so will you. Back when there was more discussion of scuba here, there was someone from your (very) general vicinity with a tagline about the St. Lawrence being comparatively warm, clear freshwater diving. Certainly people from this general area do drive 4-5 hours to go diving up there. While you might be that far yourself, depending which part of Quebec you are from, it's a good place to go get more time underwater without as much "opportunity cost" as tropical locations, or the cold murk of lake thermoclines and the north atlantic. No coral, but there are wrecks and some wildlife. Probably wait for summer... If you and your spouse both like to dive, a liveaboard dive boat is a great way to get a lot of diving in when you do go to a tropical destination. 5 dives a day is very nice. If you were aware of your pressure and ran out of air at 20 feet, you were failing to act appropriately on your awareness. You get away with that behavior until you don't, and then you get shipped home in a bag. There certainly wasn't any 3 minute safety stop at 15 feet... If you ascend from 60 feet, you will have plenty of (too much actually) air in your lungs, even if you just exhaled - remember that the air in your lungs will expand as you go up - just keep blowing bubbles. Our sub guys train for it in a 100 foot deep tank, if I recall correctly. Some TV show about the training showed their "don't hold your breath, stupid" training tool - a nearly empty sealed plastic bag released at the bottom of the tank, which burst somewhere around 20 feet. You will have to get over a desire to breathe in, however. Some of the more technical organizations apparently train for using the BC as a crude rebreather in that instance, but if you are going that route, you'll want to be sure you disinfect the inside of the BC - our instructor commented that you could get some great lung infections from that practice. Actually practicing free ascents is a considerable DCS risk - limited if you just go down to 60 feet and immediately ascend - also limited if you opt to stop at 15 feet rather than take your practice all the way to the surface. You might want to leave the camera to your air-sipping wife - even with 100+ camera dives, merely taking the thing causes a noticeable increase in air consumption for whichever one of us is using it. We've arrived a policy of just not taking the camera on the first dive of a trip - it's more task loading when it's not a good idea, since it's usually months between trips and the first dive is always a bit of a shakedown and refreshing habits/skills. While someone else commented that they "*GASP* even hold their breath" or words to that effect for camera positioning, I will stop breathing, but not hold my breath - there is a difference, and the difference is that holding your breath involves stopping up your airway, and not breathing does not. As such, not breathing does not involve any risk of lung overpressure injury. There are better fins than the old things you have, but what fins are better can be a bit of a religious issue, and probably also depends upon intended use to an extent. I like the Apollo bio-fins (with the slit), and they seem to have some decent actual test data supporting better efficiency. If you read magazines, Dive Training is the one we've kept up the subscription to, though you have to ignore the gear press releases, since they are press releases, not reviews. 11 years ago Rodale's Scuba Diving had the only actual gear reviews that would EVER say anything negative about anyone's gear, or do any actual testing, but the rest of the magazine was crap - once we got our gear bought we dumped the subscription. No idea what it's like now, or if it's even still in business. SignatureCats, coffee, chocolate...vices to live by > Just a few more comments - what the heck, it's actual scuba, which seems > to have gone missing from rec.scuba since the last time I was reading [quoted text clipped - 19 lines] > the hour with 750-1500 lbs. Coincidentally, those were dives 11& 12 for > him. He'll get better, and so will you. Well, for a newsgroup there is surprising consensus ;-) on the above points, so it's sticking... > Back when there was more discussion of scuba here, there was someone > from your (very) general vicinity with a tagline about the St. Lawrence > being comparatively warm, clear freshwater diving. Not sure where it's so clear. A lot of people dive in the Gaspe, which is definitely saltwater, clear and cold. Though not as cold as les Escoumins (2'C) which is definitely dry suit country. You might get away with a thick wetsuit at Gaspe. I think. > Certainly people from > this general area do drive 4-5 hours to go diving up there. While you [quoted text clipped - 3 lines] > thermoclines and the north atlantic. No coral, but there are wrecks and > some wildlife. Probably wait for summer... I will definitely look to dive here to increase my experience. My SO is less willing. I (chubby) did not need a wet suit at Cancun or San Andres, but she needed one badly (thin). (After a 15 minute pool exercise she was shivering w/o a WS). There are a few dive shops along my usual routes and when I have time I'll drop in to ask about organized outings. I'm looking to buy some used gear as well. I'd rather learn about what I like or not from used gear before committing to new. Feedback from others helps too - esp. if I can find some divers about my size. > If you and your spouse both like to dive, a liveaboard dive boat is a > great way to get a lot of diving in when you do go to a tropical [quoted text clipped - 4 lines] > that behavior until you don't, and then you get shipped home in a bag. > There certainly wasn't any 3 minute safety stop at 15 feet... Like I said - well aware and deliberate on my swim back to the boat on a shallow climb. That particular dive was to 70 ft. The instructor did not practice safety stops except on deep dives (100'+). I know that is against all prudence, but that's the way they seem to do things there. The sole time we did a 3 minute stop was on the dive to 110'. > If you ascend from 60 feet, you will have plenty of (too much actually) > air in your lungs, even if you just exhaled - remember that the air in > your lungs will expand as you go up - just keep blowing bubbles. I have no problem with the physics and needing continuous exhalation. It's "doing it" that intrigues me I suppose. > Our sub > guys train for it in a 100 foot deep tank, if I recall correctly. Some > TV show about the training showed their "don't hold your breath, stupid" > training tool - a nearly empty sealed plastic bag released at the bottom > of the tank, which burst somewhere around 20 feet. I visualize my lungs as quite fragile throughout the dive - so that's a good reminder to exhale all of the time. Though going over coral/plants when skimming the bottom I would tend to hang on to the air for a few seconds until momentum would keep me going up. > You will have to get over a desire to breathe in, however. Some of the > more technical organizations apparently train for using the BC as a > crude rebreather in that instance, but if you are going that route, > you'll want to be sure you disinfect the inside of the BC - our > instructor commented that you could get some great lung infections from > that practice. No doubt. But I'm fairly clear on the need to exhale. (OTOH I'm also the guy who starts the dive bleeding the BCD while confidently breathing from my snorkel - at least until I choke on water going down. So a clear head and intention is needed. Visualization. etc.). > Actually practicing free ascents is a considerable DCS risk - limited if > you just go down to 60 feet and immediately ascend - also limited if you > opt to stop at 15 feet rather than take your practice all the way to the > surface. As I said, I intend (too strong a word, perhaps) to do the first one from 30' and then work my way down on later dives. It could be that I do it once and for all at 30' and I'll be content with that. Sounds more and more like a plan, actually. > You might want to leave the camera to your air-sipping wife - even with > 100+ camera dives, merely taking the thing causes a noticeable increase [quoted text clipped - 3 lines] > between trips and the first dive is always a bit of a shakedown and > refreshing habits/skills. Excellent advice. While I'm a proficient photographer who usually works fully manual, I suspect that for diving I'll be as automatic as possible in the camera. And I have no stunning ambitions for that photography (initially) - I'll probably get a P&S with a pressure enclosure. I know that's not particularly "photo worthy" but at least for close ups the colours render well with the flash. Shots of other people look pretty lame (like the ones I posted... not my camera). > While someone else commented that they "*GASP* even hold their breath" > or words to that effect for camera positioning, I will stop breathing, > but not hold my breath - there is a difference, and the difference is > that holding your breath involves stopping up your airway, and not > breathing does not. As such, not breathing does not involve any risk of > lung overpressure injury. I'd be more likely to exhale and then pull in a quarter/half breath. Kinda like shooting. IAC, photography is not the highest item on the list by far. I'm a slow, deliberate, tripod kind of photographer, so I'd need a different plan under water. > There are better fins than the old things you have, but what fins are > better can be a bit of a religious issue, and probably also depends upon > intended use to an extent. I like the Apollo bio-fins (with the slit), > and they seem to have some decent actual test data supporting better > efficiency. I could probably generate better test data for a pair of strap on bricks. That's a cynical remark regarding manufacturer influenced test data. People (not targeting you) tend to have a lot of ownership loyalty and hence after plunking down cash on something, they defend it to absurdity. (This applies to cameras, cars, cheese and very soon to your nearest iPad owner). > If you read magazines, Dive Training is the one we've kept up the > subscription to, though you have to ignore the gear press releases, [quoted text clipped - 4 lines] > subscription. No idea what it's like now, or if it's even still in > business. Most magazines have turned into gear promos. And again, I'm not talking about diving alone. Are there specifically good scuba gear review websites? For example, for photography, dpreview.com is spec. exhaustive and does pretty good testing. They have their biases, of course, but you sure learn a lot more about manufacturers offerings than you ever could perusing magazines or co. literature. Signaturegmail originated posts are filtered due to spam. >> Just a few more comments - what the heck, it's actual scuba, which seems >> to have gone missing from rec.scuba since the last time I was reading [quoted text clipped - 72 lines] >I have no problem with the physics and needing continuous exhalation. >It's "doing it" that intrigues me I suppose. Did you not do an ESA from 15 feet on your instruction dives? I missed doing it on my lake dives due to some confusion about which instructor was taking which student and I had to do it on my first ocean dive after a rather long kelp crawl from the boat with the instructor. My course was combined NAUI/PADI. Fifteen feet only gives you a taste of what it would be like from 30 or 60 but it's enough to make sure you understand the principles. We were also taught to keep the regulator in your mouth just in case you couldn't resist the desire to inhale or in an actual OOA situation there might be enough left on the way up to cover the ascent. >> Our sub >> guys train for it in a 100 foot deep tank, if I recall correctly. Some [quoted text clipped - 18 lines] >from my snorkel - at least until I choke on water going down. So a >clear head and intention is needed. Visualization. etc.). This is a bad idea. As a newb I tended to delay putting the regulator in my mouth to the very last minute too. This can only make you suck more air on the dive and I have demonstrated it to myself several times. I pretend the snorkel isn't there. On the surface, swimming out to a descent line, OK, the snorkel is in. But in that case it's a good idea to stop at the line and take the snorkel out and rest and recheck with your buddy. Then put the regulator in your mouth and begin your descent together. With a snorkel you are getting just a little bit more CO2 from the spent air in the tube vs. without and this tends to increase your respiration rate, it's a reflex you have very little control of. You are also increasing your overall anxiety about the dive by initially worrying about your air consumption even before the dive begins and adding to the busy-ness at the surface playing with regulators and snorkels and which one is appropriate. Sucking water through a tube because you played games with the descent and then suppressing coughs while you swap to the regulator is just silly. You also want to make sure your regulator is in your mouth and properly seated and breathing correctly before you are suddenly at 3 feet with no air in your lungs and a tangled rig. The goal is to be prepared, calm and ready to begin your descent BEFORE you begin your descent. Diving is in stages, preparation, donning, entry, descent, trim, swim, ascent, safety stop, surface, exit. Each has things you need to be concerned about and focused on in addition to your situational awareness on your pressure, depth and your buddy. Focus on each stage and you will be calmer and more competent. The Zen of diving is confidence in your training and your skills and to not fight the element you are in but to ride it like the fishes. When you are calm and not fighting current and not needlessly pushing your own weight of water your air consumption will decrease dramatically. I went from 40 minutes of air on a 30 foot dive to 70 minutes according to the computer once I finally became comfortable and experienced. A one hour+ dive to 35 feet in warm water kissing sea cucumbers was nothing. Proper trim and buoyancy control help immensely. Others have commented about how wasteful mask clearing and equipment problems can be. This goes to preparation. As a snorkeler I tended to fight the water more, as a scuba diver I have learned to be 'one' with the water. It has given me a deep appreciation of the beauty and skill of real free divers who can free dive for minutes at a time. >> Actually practicing free ascents is a considerable DCS risk - limited if >> you just go down to 60 feet and immediately ascend - also limited if you [quoted text clipped - 5 lines] >do it once and for all at 30' and I'll be content with that. Sounds >more and more like a plan, actually. As a confidence builder with an experienced buddy, preferably a decent instructor, a 30 foot exercise would be a good idea for a first dive of the day. Be aware that the reason they do it from 15 feet is to minimize the risk to you and your instructor because it's essentially a bounce dive and the ascent is more rapid than recommended. >> You might want to leave the camera to your air-sipping wife - even with >> 100+ camera dives, merely taking the thing causes a noticeable increase [quoted text clipped - 33 lines] >bricks. That's a cynical remark regarding manufacturer influenced test >data. I have experienced cheap stuff, Apollo Prestige fins, Force fins, and Apollo Bio fins, I like the Bio fins best. The Prestige fins wobbled and yawed more and generally worked my ankles more, leading to a tendency to cramp. Force fins felt lighter but I couldn't get the hang of them and they seriously sucked on the surface or walking to the boat gate. The Bio fins seem more stable and I cramp less, I can also kick slower than my buddy for the same swim speed. I bought the Prestiges as a beginner, inherited the Force fins, bought the Bios. >People (not targeting you) tend to have a lot of ownership loyalty and >hence after plunking down cash on something, they defend it to >absurdity. (This applies to cameras, cars, cheese and very soon to your >nearest iPad owner). Very true. > With a snorkel you are getting just a little bit > more CO2 from the spent air in the tube vs. without and this tends to > increase your respiration rate, it's a reflex you have very little > control of. I find it amusing that you accept this as fact, but agree with Greg that it's "ludicrous" that there is an effect, small but non-zero, of rebreathing more of the excess nitrogen which is coming out with the exhaled CO2 that you are breathing back in. It's exactly the same thing - a snorkel adds dead space to your airway, increasing the amount of whatever your breathe out that you breathe right back in - so if you are offgassing nitrogen, you are breathing in a snorkels-worth of what you breathed out every time, meaning that what you breathe in is richer in nitrogen and carbon dioxide than it would be if you did not have a snorkel in your mouth. That does make offgassing less effective than unrestricted breathing. It raises the partial pressure of nitrogen in your lungs. If you think there is no effect, try adding a 10 foot extension to a snorkel (stay on dry land) and breathe through it until you pass out. You'll be passing out from lack of oxygen, but it illustrates the effect of the tube - the effect of a shorter tube is less, but it's not nothing. All I said was that it is not quite as effective to snorkel at the surface as to breathe freely at the surface - not "OMG you can't possibly do that!" I do it myself sometimes, when the site permits. SignatureCats, coffee, chocolate...vices to live by >> With a snorkel you are getting just a little bit >> more CO2 from the spent air in the tube vs. without and this tends to [quoted text clipped - 21 lines] >the surface as to breathe freely at the surface - not "OMG you can't >possibly do that!" I do it myself sometimes, when the site permits. Boy, we are just full of misinterpretation aren't we? I mistake Greg's "ludicrous" as a reply to a statement I made and you mistake me discussing chemoreceptor reflex for agreement with Greg. In that case I was referring to increased respiration due to CO2 elevation and the subsequent anxiety during a dive. My disagreement with Greg was that it looked to me at first glance that he was applying the "ludicrous" to something I said. I thanked him for clarification but I don't believe I stated I agreed with him about that merely breathing through a snorkel inhibited off-gassing, I also didn't explicitly disagree with your statement either, but thanks for the notice. On Jan 29, 7:52 pm, Ecnerwal <MyNameForw...@ReplaceWithMyVices.Com.invalid> wrote: > In article <cgn6m5138gm11tirlvors86afv25shl...@4ax.com>, > [quoted text clipped - 15 lines] > unrestricted breathing. It raises the partial pressure of nitrogen in > your lungs. But exhaled air is 78% nitrogen versus the 79% in inhaled air. With every breath of recycled air from a snorkel's dead space, you're actually reducing the percentage of nitrogen inhaled versus inhaling fresh air. Duh. > On Jan 29, 7:52 pm, Ecnerwal > <MyNameForw...@ReplaceWithMyVices.Com.invalid> wrote: [quoted text clipped - 23 lines] > > Duh. this discussion and ptII has been very enlightening - nice discussion and points. Now shut down the thread and lets get back to guns, politics, and global warming!@ Just kidding - Greg when do you leave on your next trip? I'm going to Vegas and betting on a volcano eruption or an asteroid strike. Do you have any preferences? Have a good trip! > Just kidding - Greg when do you leave on your next trip? I'm going to > Vegas and betting on a volcano eruption or an asteroid strike. Do you > have any preferences? An asteroid strike would be cool to see underwater, though potentially a bit unnerving. Volcano eruption is far more likely in Indonesia, though I'm not sure if there's anything too active near where we'll be. Since I'll have to be staying in touch with work (I never really get a "vacation"), the biggest calamity I can envision would be a failure of their rudimentary cell-phone system or something going wrong with their satellite internet hookup. One or the other would be survivable, but both and I'm swimming home. >> Just kidding - Greg when do you leave on your next trip? I'm going to >> Vegas and betting on a volcano eruption or an asteroid strike. Do you [quoted text clipped - 8 lines] > wrong with their satellite internet hookup. One or the other would be > survivable, but both and I'm swimming home. With your luck on dive trips, you're likely to see both. :-) Signature-- Popeye "If one does as God does enough times, one will become as God is." -Dr. Hannibal Lector. www.finalprotectivefire.com http://picasaweb.google.com/Popeye8762 > Just kidding - Greg when do you leave on your next trip? > Have a good trip! Not until May. Mid May. Over three more months to go. On Jan 29, 7:55 am, Ecnerwal <MyNameForw...@ReplaceWithMyVices.Com.invalid> wrote: > While someone else commented that they "*GASP* even hold their breath" > or words to that effect for camera positioning, I will stop breathing, > but not hold my breath - there is a difference, and the difference is > that holding your breath involves stopping up your airway, and not > breathing does not. As such, not breathing does not involve any risk of > lung overpressure injury. There is exactly zero risk of lung overpressure injury when there is no change in depth. Therefore, holding one's breath (or stopping breathing, which is exactly the same thing, there is no difference) when one is neutral and maintaining an exact depth does not involve any risk of lung overpressure injury. It's merely important to recognize that if one isn't exactly neutral and inadvertently starts to ascend, it's necessary to exhale a bit. >There is exactly zero risk of lung overpressure injury when there is >no change in depth. Therefore, holding one's breath (or stopping [quoted text clipped - 3 lines] >recognize that if one isn't exactly neutral and inadvertently starts >to ascend, it's necessary to exhale a bit. Not until you've reached the desired depth. When you're at 60 ft, a breath hold ascent to 55 won't hurt. >> There is exactly zero risk of lung overpressure injury when there is >> no change in depth. Therefore, holding one's breath (or stopping [quoted text clipped - 6 lines] > Not until you've reached the desired depth. When you're at 60 ft, a > breath hold ascent to 55 won't hurt. Doesn't make sense. That's most of 2 atm. I'd just let air out all the way. Signaturegmail originated posts are filtered due to spam. >Doesn't make sense. That's most of 2 atm. I'd just let air out all the >way. No it's not. Alan Browne wrote: > First, thanks for all your replies, gents. Very educational. > > The Swiss couple I met (and usually had a drink or three with almost > daily) insisted on the merits of their computers. (snip) When all the yammering is over, come back to this one. Tables were made for men who made their living under water. When they were adopted by recreational weenies they were made more "conservative" for the very mistaken reason that more conservative = less bent, and the correct excuse that more conservative = happier corporate counsel. Computers have extended that trend, to the point that most, if not all, computer algorithms are as indicative of exposure as a sundial is indicative of the time of day. But folks are impressed by computer science, even if the results are a very rough estimate. After all, it's a rough estimate made with a COMPUTER! That's the main reason more dive operations are insisting on computers: they cut yer dive real short and the boat crew gets home a lot earlier. Where a computer comes in real handy is in multi-level diving, wall diving especially. You can drop to 240, noodle on up the wall, poke around the shallows under the boat, and get a good 50+ minute dive in. As for air consumption, it will improve as you get more dives in and learn to husband yer air. As a big guy, you will almost certainly always use more air than most of the little girls. Get steel 100s and a shop that will overfill them. Or 120s. Only in desperation go to doubles (Curtis comment?). And enjoy. esg > Alan Browne wrote: > > First, thanks for all your replies, gents. Very educational. [quoted text clipped - 13 lines] > science, even if the results are a very rough estimate. After all, it's > a rough estimate made with a COMPUTER! That's been my impression since I've been hearing/reading about them. This dive computer world seems like compounding fudge factor on compounding fudge factor. So they can integrate your depth-time profile quite accurately, but for the N2 absorption they apply biases, fudges and safety factors to the point that there is more over/outerlap for corporate safety than actual guidance on your body condition. (I had a bit of an argument with the Swiss guy over this. He's convinced of the accuracy of the computer because it integrates so well while acknowledging what the models know about individuals (or even an average of all) can't even be quantified accurately. Like measuring your position to within 5 meters with a GPS but only having a 1970's garage map to navigate with...) Have there been any efforts at instruments that somehow measure actual N2 in body tissues? With recent advances in surgically implantable data gatherers, perhaps a subcutaneous sensor could report to the computer actual N2 in the tissues. What is the tissue that releases it slowest? If it's fat, I've got a lot of potential sites (and not all in my head). > That's the main reason more dive operations are insisting on computers: > they cut yer dive real short and the boat crew gets home a lot earlier. > > Where a computer comes in real handy is in multi-level diving, wall > diving especially. You can drop to 240, noodle on up the wall, poke > around the shallows under the boat, and get a good 50+ minute dive in. I'm a long way from that... > As for air consumption, it will improve as you get more dives in and > learn to husband yer air. As a big guy, you will almost certainly always > use more air than most of the little girls. Get steel 100s and a shop > that will overfill them. Or 120s. Only in desperation go to doubles > (Curtis comment?). What's the amount of overfill that a shop might go? Wouldn't that reduce the life of the bottle? Would it cause additional wear or damage to the first regulator? Signaturegmail originated posts are filtered due to spam. <snip> > This dive computer world seems like compounding fudge factor on > compounding fudge factor. Yes and no. Different algorithms yield different no-deco limit (NDL) times and different stop times for decompression diving. > So they can integrate your depth-time profile quite accurately, but for > the N2 absorption they apply biases, fudges and safety factors to the > point that there is more over/outerlap for corporate safety than actual > guidance on your body condition. Perhaps. My sense, though, is that Pelagic's (they are OEM for, e.g., Oceanic and Mares computers) algorithm is not excessively conservative. My Pelagic (Oceanic) computers "get bent" and go into gauge mode several times a season, but I can't recall that happening when I'm not using Trimix (which they don't understand) or using enriched mixes for accelerated deco (which they don't understand) or both. From diving with others who have Suuntos, I know mine are markedly less conservative than Suunto's RGBM algorithm. Wikipedia has what seems at first glance (I have not read the entire thing, nor any of it carefully) a good summary at: http://en.wikipedia.org/wiki/Dive_computer#Algorithms Oceanic's site seems informative as well: http://www.oceanicworldwide.com/flash/OCE_dc101.pdf > (I had a bit of an argument with the Swiss guy over this. He's > convinced of the accuracy of the computer because it integrates so well > while acknowledging what the models know about individuals (or even an > average of all) can't even be quantified accurately. Like measuring > your position to within 5 meters with a GPS but only having a 1970's > garage map to navigate with...) Yeah, kinda like arguing with someone about what's in their computer being wrong in any context. ("You deposited the check!" "Sir, you have not paid the bill.") The computer says it, so it must be true. Mike and I have discussed risk management vs. conservatism in this forum, and do not agree. I still maintain that you are less likely to get bent if you are more conservative (stay further from the "M value"). Having said that, there are reasonable limits to conservatism and risk management and while I have not observed anyone getting bent using a Suunto computer to control a dive I have also not observed anyone using a Pelagic computer to control a dive and generally the latter seems to let you surface rather faster. It's hard to make a truly informed decision in this space, though, as individual variation--and even variations for a particular individual from day to day--can have a big effect on one's susceptibility to DCS. This is not an exact science and might never be one. > Have there been any efforts at instruments that somehow measure actual > N2 in body tissues? Not practical. Every tissue absorbs and offgasses at different rates with different gases. Most models are Haldanean to some degree and use a series of "compartments" with different half-times to simulate and predict how your tissues will behave. This approximation is likely better than could be achieved with any noninvasive monitoring. Never forget, though, that it's all approximation, whether from tables, wheels, computers, or predictions made from reading the patterns that result from casting the bones of small animals into the sand. Some divers claim their knowledge and intuition keeps them safe after a while, given accurate time and depth information, and while I can see how that could work (and even work well), I vastly prefer more-objective guidance in the form of precut tables or computers. > With recent advances in surgically implantable data gatherers, perhaps a > subcutaneous sensor could report to the computer actual N2 in the > tissues. What is the tissue that releases it slowest? If it's fat, > I've got a lot of potential sites (and not all in my head). A sub-q sensor, if practical, would show the N2 level in adipose tissue only, not in muscle, nerve, bone, liver, etc. tissues. <snip> > What's the amount of overfill that a shop might go? Wouldn't that > reduce the life of the bottle? Would it cause additional wear or > damage to the first regulator? In cave country filling 2400psi-rated tanks to 3000psi is routine. But for the diving you are doing a 100cf or 120cf tank filled to rated pressure is likely to do just fine for quite a while. While many believe these practices are safe (and nobody has dead bodies to point to to prove they are not safe so far as I know) I suggest you pick one new risk at a time to learn about and manage. Treat learning to dive just like learning to fly. They have a lot in common. The runway behind you, the altitude below you, and the fuel you left behind are a lot like the equipment and gas you left on the surface. Both demand forethought. Gas (avgas or breathing gas) planning is a really good idea for both. The most common emergency for both is...running out of gas. Both happen in three dimensions in a medium that itself is rarely still. Both can kill the unskilled or careless. And so on. For instance, everyone who flies knows that if the temperature is 10F the airplane will carry more payload and still hit its numbers, but only in Alaska is it legal to add to gross takeoff weight. It's not legal to transport an overfilled tank interstate but people in cave country routinely overfill tanks and so do many wreck divers in the Northeast. Would you tell a student or new PP it's OK to overload an airplane when it's cold out in the Lower 48? Take it a step at a time. Read everything but change what you do slowly as you gain experience so that you know for yourself why you are changing it. And go blow more bubbles. It's just as much fun as turning avgas into noise--and can be cheaper! SignatureJohn Eells > <snip> >> [quoted text clipped - 49 lines] > from day to day--can have a big effect on one's susceptibility to DCS. > This is not an exact science and might never be one. Before buying a computer I'll have to research it well. I have nothing against conservativism, but being shorted over an over abundance of caution irks me as well. >> Have there been any efforts at instruments that somehow measure actual >> N2 in body tissues? [quoted text clipped - 27 lines] > > In cave country filling 2400psi-rated tanks to 3000psi is routine. But The tanks at San Andres were filled to 3000 - I assumed that was their nominal rating. > for the diving you are doing a 100cf or 120cf tank filled to rated > pressure is likely to do just fine for quite a while. While many believe [quoted text clipped - 4 lines] > Treat learning to dive just like learning to fly. They have a lot in > common. The runway behind you, the altitude below you, and the fuel you That's altitude "above" you... > left behind are a lot like the equipment and gas you left on the > surface. Both demand forethought. Gas (avgas or breathing gas) planning > is a really good idea for both. The most common emergency for both > is...running out of gas. Both happen in three dimensions in a medium > that itself is rarely still. Both can kill the unskilled or careless. > And so on. My only engine failure was on short final in a downdraft ... I landed on the grass short of the runway... (carburetor had recently been overhauled). Passengers were impressed. Same aircraft had a failure two weeks later. That's when the carb was revealed as the problem area. > For instance, everyone who flies knows that if the temperature is 10F > the airplane will carry more payload and still hit its numbers, but only > in Alaska is it legal to add to gross takeoff weight. Never heard of that. Weight also goes to structural and g-load limits, so such would surprise me. > It's not legal to > transport an overfilled tank interstate but people in cave country [quoted text clipped - 6 lines] > changing it. And go blow more bubbles. It's just as much fun as turning > avgas into noise--and can be cheaper! Surely. I'm just in that lovely state of ignorance and wanting to fill in and do more. Meanwhile it's a balmy -7'C outside (was -17 yesterday...) so my next dive is a little ways away...). Thx, Alan. Signaturegmail originated posts are filtered due to spam. On Jan 31, 10:48 am, Alan Browne <alan.bro...@FreelunchVideotron.ca> wrote: > Before buying a computer I'll have to research it well. I have nothing > against conservativism, but being shorted over an over abundance of > caution irks me as well. I have the most conservative computer on the market, AFAIK, yet my dive profiles don't differ much from the average avid recreational diver in my experience. If anything, I tend to be a bit more aggressive than average, but I can't claim that I've really ever been "shorted" bottom time. Right now, you're being shorted because you're an airhog. Only when you have the air consumption rate or the tanks to be able to dive longer than my regular profiles will "shorting" be a concern, and that's only if you're diving on your own or with a dive operation that allows longer-than-usual dives. One caveat, though: I speak from the perspective of diving nitrox on most every dive I do. I haven't done more than two dives in a row on plain old air in years, probably not since I've had my Suunto. > > In cave country filling 2400psi-rated tanks to 3000psi is routine. But > > The tanks at San Andres were filled to 3000 - I assumed that was their > nominal rating. That's the standard fill pressure for an aluminum 80, which is pretty much the standard at dive resorts around the world (though other tanks may be available), with the exception of a few places that have funky European tanks with weird dimensions and capacities measure in liters so nobody has a clue how much air they really have. 2400 psi rated tanks are steel tanks, which are supposedly a lot more forgiving when they burst (i.e., they might just spring a leak rather than explode cataclysmically). They come in various sizes, but 72, 95, and 112cf are most common I believe. A steel 112 filled to over 3000 gives you lots of air for a recreational dive. > So they can integrate your depth-time profile quite accurately, but for > the N2 absorption they apply biases, fudges and safety factors to the > point that there is more over/outerlap for corporate safety than actual > guidance on your body condition. You want to ride the hairy edge, get a Cochran, not a Suunto. As I said before, get one that suits your style - if your style is push it to the limit, or beyond, that's where you want to be - Cockroach is the manly man's testosterone-dripping statement that mere nitrogen can be mastered with an application of chutzpah and a computer that says "go for it - no limits! (...or at least very few.)" When discounting conservatism in recreational tables and computers, remember that the Navy tables were developed for young fit men, not old men, fat men, old fat men, or women of any sort. Furthermore, from what I understand, Navy protocol is that there's always a chamber at hand, so they can afford a few hits, given a low level of bother to whip the diver into the chamber at the earliest suspicion that all may not be well. And at the risk (big whoop) of losing about 95% of y'all, that whole drinking thing is also not a great mix with diving, given a decided connection between dehydration and DCS, and inebriation masking symptoms of DCS. I'm not a real diver, I know - all *real* divers drink and smoke as much as possible, especially on dive trips. When I need to make a million dollars, I'll just invent the ScubaSmoke, so going diving won't interfere with the continuous pursuit of lung cancer. The last liveaboard I was on had free booze, though they did request that you stop diving for the day when you started drinking. Seemed to be a big deal to some of our fellow travelers. Morning dives for some of them were interesting, or just not an option, depending on the night before. SignatureCats, coffee, chocolate...vices to live by >The last liveaboard I was on had free booze, though they did request that you >stop diving for the day when you started drinking. Seemed to be a big >deal to some of our fellow travelers. Morning dives for some of them >were interesting, or just not an option, depending on the night before. Other than Nekton, free booze is the norm on most if not all liveaboards I dive from. Most people I see take it in stride and are well rested and ready to dive each morning. > On Sat, 30 Jan 2010 23:18:35 -0500, Ecnerwal > [quoted text clipped - 7 lines] > liveaboards I dive from. Most people I see take it in stride and are > well rested and ready to dive each morning. Yeah, even for someone like me who really likes his free booze, I figure it's a lot cheaper to sit at home and drink expensive booze than to fly halfway around the world to take an expensive liveaboard just to drink cheap free booze and sit out dives. On all the free booze liveaboards I've done, I've always been proud to not only get the most of my money's worth out of the free booze, but also be one of the first up in the morning so I could drink free coffee and take my time prepping my camera. Plus, with all that DCS risk that the free booze imposes, combined with 4-5 dives a day, you'd think people would be getting bent on liveaboards all the time, yet I've never seen that aboard any of my trips. Maybe all those too-conservative dive computers are doing a great job! >> So they can integrate your depth-time profile quite accurately, but for >> the N2 absorption they apply biases, fudges and safety factors to the [quoted text clipped - 7 lines] > with an application of chutzpah and a computer that says "go for it - no > limits! (...or at least very few.)" I hear you. I'm not looking to explore the onset of the bends, I just don't want to be cheated out of dive time by lawyers. > When discounting conservatism in recreational tables and computers, > remember that the Navy tables were developed for young fit men, not old [quoted text clipped - 15 lines] > deal to some of our fellow travelers. Morning dives for some of them > were interesting, or just not an option, depending on the night before. I tend to think that drinking and diving are a bad mix and I'm a fairly moderate drinker on vacation, eg: I don't get drunk, I'm usually in bed early, etc. ('cause I'm up early for the warm light...). I don't smoke. I'm losing weight. Well I did on vacation. But some of it seems to have found a flight home. Signaturegmail originated posts are filtered due to spam. On Jan 31, 10:52 am, Alan Browne <alan.bro...@FreelunchVideotron.ca> wrote: > > You want to ride the hairy edge, get a Cochran, not a Suunto. As I said > > before, get one that suits your style - if your style is push it to the [quoted text clipped - 5 lines] > I hear you. I'm not looking to explore the onset of the bends, I just > don't want to be cheated out of dive time by lawyers. That's too bad. I could give you a good deal on a used Cochran. You could save big $$ by never having to dive nitrox and still keep up with everyone else. Seriously. >That's too bad. I could give you a good deal on a used Cochran. You >could save big $$ by never having to dive nitrox and still keep up >with everyone else. Seriously. Sounds like a good deal. That's how I dive, except with an Oceanic instead of a Cochrane. > On Jan 31, 10:52 am, Alan Browne<alan.bro...@FreelunchVideotron.ca> > wrote: [quoted text clipped - 12 lines] > could save big $$ by never having to dive nitrox and still keep up > with everyone else. Seriously. Never went to "Selling iceboxes to Eskimos" school, eh? Signaturegmail originated posts are filtered due to spam. > Have there been any efforts at instruments that somehow measure actual > N2 in body tissues? It's irrelevant in issues addressed by a dive computer (narc is a different matter, of course). The question is how the N2 (and other gases) react when the ambient pressure is reduced. The Haldanian rule of thumb is that you can halve the ambient pressure, wait for bubbles to be reabsorbed (deco), then halve the pressure again. With adjustments to allow patent defense, that's the basis for all the tables and computer algorithms in use. > With recent advances in surgically implantable data gatherers, perhaps a > subcutaneous sensor could report to the computer actual N2 in the > tissues. What is the tissue that releases it slowest? If it's fat, > I've got a lot of potential sites (and not all in my head). "Slow" tissues and "fast" tissues are a refinement of the Haldanian algorithm, a mathmatical construct not a physiologic concern despite the fact that specific physiologic tissues may (or may not) offgas at different rates than others. > > What's the amount of overfill that a shop might go? Wouldn't that > reduce the life of the bottle? Would it cause additional wear or > damage to the first regulator? 10% is pretty standard, and allowed by most manufacturing standards. 15% is common and 20% is frequently seen on tech dives. The life of a bottle is measured in cycles, and metallurgists will tell you that 20% overfills will reduce the life of steel bottles slightly, aluminum bottles more. As I remember (someone will correct me) the life of my Pressteel 100s is 30,000 cycles, so I may have to pass on that last 100 dives. If your first stage is not capable of 5500 - 6000 #, buy a different first stage. esg > As for air consumption, it will improve as you get more dives in and learn > to husband yer air. As a big guy, you will almost certainly always use > more air than most of the little girls. Get steel 100s and a shop that > will overfill them. Or 120s. Only in desperation go to doubles (Curtis > comment?). Way too early for this guy to consider doubles. That said, I dive them almost exclusively, for good reasons. Redundancy is not an option for me. Doubles handle way better than large singles in the water, and dub AL80s are easy enough for me to climb a boat ladder while wearing. Mine are also likely to have some HE in the mix. Down side, only know one shop in the FL Keys that rents them, and a few places in FL cave country, foreign locations require some research, so ownership is damn near a must. Good bands are not cheap, and a good manifold may cost more than the tanks, so figure each set a chunk of change. Better to get more dives in, learn to relax and enjoy, don't worry about consumption beyond having a safe reserve, then maybe try the bigger tanks Mike suggested. Rent, don't purchase at first. Tank selection is not as simple as suggested for optimal results, and a backplate & wing should be considered. As far as big guys using more, yep, but it can be compensated for. Consider me at least as big as "Alan Browne". If I'm swimming against a flow, working or being playful, I will use more, but I can also make an AL80 go for 100 minutes on shallow putting around dives / deco. Biggest trick is RELAX. Also supposed to help if not cold, but have little personal experience in that matter for comparison. Curtis > Better to get more dives in, learn to relax and enjoy, don't worry about > consumption beyond having a safe reserve, then maybe try the bigger tanks > Mike suggested. Rent, don't purchase at first. Tank selection is not as > simple as suggested for optimal results, and a backplate & wing should be > considered. Excellent advice for any diver, especially newbie - rent, borrow, try out stuff before you make the big commitment. Then buy used from the folks that didn't. esg >> Better to get more dives in, learn to relax and enjoy, don't worry >> about consumption beyond having a safe reserve, then maybe try the [quoted text clipped - 5 lines] > out stuff before you make the big commitment. Then buy used from the > folks that didn't. That is part of the plan - buy used, learn, and replace new (or used) as I go along. Signaturegmail originated posts are filtered due to spam. >As for air consumption, it will improve as you get more dives in and >learn to husband yer air. As a big guy, you will almost certainly always >use more air than most of the little girls. Get steel 100s and a shop >that will overfill them. Or 120s. Only in desperation go to doubles >(Curtis comment?). I'll comment too. I'm completely at home in the water. I'd dive everyday if I could. But, on my last trip to Cozumel, I went through more air than my smaller counterparts every time. On our one dive with a ripping current where we all had to swim perpendicular to the current to get to another reef, I went through far more air. >>As for air consumption, it will improve as you get more dives in and >>learn to husband yer air. As a big guy, you will almost certainly always [quoted text clipped - 7 lines] > with a ripping current where we all had to swim perpendicular to the > current to get to another reef, I went through far more air. That seems a little odd, given the shape I assume you to be in. As big as I am, my air consumption is pretty good. In the Gilboa quarry in Ohio, in cold water, it was the same as Wagner's (a Rec.scuban of past fame, 160 triathlete). At one point, at 20 ft, reading a book, I was getting 3 hrs out of an AL80. Signature-- Popeye "If one does as God does enough times, one will become as God is." -Dr. Hannibal Lector. www.finalprotectivefire.com http://picasaweb.google.com/Popeye8762 On Mon, 8 Feb 2010 02:50:58 -0500, "Douglas W. \"Popeye\" Frederick" <Popeye8762@gmail.com> wrote in rec.scuba: >>>As for air consumption, it will improve as you get more dives in and >>>learn to husband yer air. As a big guy, you will almost certainly always [quoted text clipped - 17 lines] > At one point, at 20 ft, reading a book, I was getting 3 hrs out of an >AL80. Go figure. I use .7cf/min to plan all my tech dives. > On Mon, 8 Feb 2010 02:50:58 -0500, "Douglas W. \"Popeye\" Frederick" > <Popeye8762@gmail.com> wrote in rec.scuba: [quoted text clipped - 22 lines] >> > Go figure. I use .7cf/min to plan all my tech dives. I could see that, on what I would consider your "advanced" tech dives. You got everything but a steam calliope. But not in your t-shirt, with an AL80, drifting a two knot current in warm water. Signature-- Popeye "If one does as God does enough times, one will become as God is." -Dr. Hannibal Lector. www.finalprotectivefire.com http://picasaweb.google.com/Popeye8762 On Mon, 8 Feb 2010 19:06:18 -0500, "Douglas W. \"Popeye\" Frederick" <Popeye8762@gmail.com> wrote in rec.scuba: >> On Mon, 8 Feb 2010 02:50:58 -0500, "Douglas W. \"Popeye\" Frederick" >> <Popeye8762@gmail.com> wrote in rec.scuba: [quoted text clipped - 29 lines] > But not in your t-shirt, with an AL80, drifting a two knot current in warm >water. The ripping current dive was at least 5 knots and I was wearing a full 3mm wetsuit. Maybe it doesn't make sense but my main dive buddy was much smaller and a few years older than me. Another who came up with lots of air left was a skinny 16 year old boy. A guy who went through about the same amount of air as me was a friend who is also advanced trimix, 26 years old and tall and athletic. Go figure. >> Doesn't make sense. That's most of 2 atm. I'd just let air out all the >> way. > > No it's not. Pressure is linear with ascent. 60 ft is about 3 atm., 0 feet is one. Where am I wrong? (PS: Please expand on your answers beyond a one liner). Signaturegmail originated posts are filtered due to spam. >Pressure is linear with ascent. 60 ft is about 3 atm., 0 feet is one. >Where am I wrong? Where did you get the 0 ft from? >> Pressure is linear with ascent. 60 ft is about 3 atm., 0 feet is one. >> Where am I wrong? > > Where did you get the 0 ft from? Your snipping everything away has not helped. I see what you mean now, 60 to 55 (I was thinking a 55 foot ascent from 60). Signaturegmail originated posts are filtered due to spam. >While someone else commented that they "*GASP* even hold their breath" >or words to that effect for camera positioning, I will stop breathing, >but not hold my breath - there is a difference, and the difference is >that holding your breath involves stopping up your airway, and not >breathing does not. As such, not breathing does not involve any risk of >lung overpressure injury. I hold my breath underwater from time to time (like when I'm diving alone and want to listen for a gas leak) and everytime I switch regulators. I also do it everytime I descend from the surface with hypoxic trimix in my back gas. I take a deep breath of air at the surface and start my decent with that until I hit about 20 feet or so. Then I'll start breathing off my back gas. On Sat, 06 Feb 2010 16:49:59 -0600, John Hanson >I take a deep breath of air at the >surface and start my decent with that until I hit about 20 feet or so. >Then I'll start breathing off my back gas. I do something like that too, except I exhale instead of inhale. I'd have to overweight myself to get your method to work. >On Sat, 06 Feb 2010 16:49:59 -0600, John Hanson >>I take a deep breath of air at the [quoted text clipped - 3 lines] >I do something like that too, except I exhale instead of inhale. I'd >have to overweight myself to get your method to work. My 55 pound wing barely supports me at the surface with double 119s, a 13cf Argon bottle, an AL80 and 2 AL40 deco/stage bottles. I also start inflating my drysuit immediately on decent and have to start adding gas to my wing around 80 feet besides that to keep me from hitting the bottom like a missile. >> While someone else commented that they "*GASP* even hold their breath" >> or words to that effect for camera positioning, I will stop breathing, [quoted text clipped - 9 lines] > surface and start my decent with that until I hit about 20 feet or so. > Then I'll start breathing off my back gas. To what advantage? Signaturegmail originated posts are filtered due to spam. >>> While someone else commented that they "*GASP* even hold their breath" >>> or words to that effect for camera positioning, I will stop breathing, [quoted text clipped - 11 lines] > >To what advantage? I'm not sure what you mean. When switching regs, I like to keep gas in my lungs seeing as how I'm maintaining my position in the water column so there is no need to exhale. When at the surface and descending with hypoxic trimix, I like to have a gas mixture (air) that will support life. When descending with that breath, the volume in my lungs is decreasing so again, there is no need to exhale and in fact, it is safer to hold ones breath. >>>> While someone else commented that they "*GASP* even hold their breath" >>>> or words to that effect for camera positioning, I will stop breathing, [quoted text clipped - 13 lines] > > I'm not sure what you mean. I'm the Newbie who started this thread. While cocky and enthusiastic I also have a great void of ignorance to fill. A blessed state - unless it involves my demise. Like Dan Bracuk, if I held my breath (with a normal air kit) I doubt I would sink even with a well voided BCD. And I tend to weight heavily. > When switching regs, I like to keep gas > in my lungs seeing as how I'm maintaining my position in the water [quoted text clipped - 3 lines] > in my lungs is decreasing so again, there is no need to exhale and in > fact, it is safer to hold ones breath. I got you, I just really don't see the advantage over simply testing the air (and mix [but there I'm really ignorant]) before descending. Well, until I to breathe from the snorkel on my way down, anyway. As I descend the descent rate seems to increase. I attribute this to the BCD (lord know what else) being compressed (even if "empty" there are bound to be pockets of air in there somewhere, esp. at the top), and my lungs being briefly compressed as a function of depth. (On one dive I landed butt first about 2 meters from a sea urchin. From then on I said, "To hell with PADI, from now on I go down head first."). Signaturegmail originated posts are filtered due to spam. >>>>> While someone else commented that they "*GASP* even hold their breath" >>>>> or words to that effect for camera positioning, I will stop breathing, [quoted text clipped - 21 lines] >Like Dan Bracuk, if I held my breath (with a normal air kit) I doubt I >would sink even with a well voided BCD. And I tend to weight heavily. Put my kit on and you will! >> When switching regs, I like to keep gas >> in my lungs seeing as how I'm maintaining my position in the water [quoted text clipped - 6 lines] >I got you, I just really don't see the advantage over simply testing the >air (and mix [but there I'm really ignorant]) before descending. I test all my gases before I dive. Always! I never test the breath of air I take before starting my descent on a hypoxic trimix dive though. I have faith that it's right around 21%. >Well, until I to breathe from the snorkel on my way down, anyway. What's a snorkel? >As I descend the descent rate seems to increase. I attribute this to >the BCD (lord know what else) being compressed (even if "empty" there >are bound to be pockets of air in there somewhere, esp. at the top), and >my lungs being briefly compressed as a function of depth. That and any neoprene you might be wearing. Plus, if you're diving wet, those air pockets (however tiny they might be) between your skin and the wetsuit will get pushed out and also cause you to be less buoyant. >(On one dive I landed butt first about 2 meters from a sea urchin. From >then on I said, "To hell with PADI, from now on I go down head first."). I never ever go down head first. Good way to get air/gas trapped in the feet of your dry suit. > On Sat, 06 Feb 2010 19:49:29 -0500, Alan Browne >> Like Dan Bracuk, if I held my breath (with a normal air kit) I doubt I >> would sink even with a well voided BCD. And I tend to weight heavily. > > Put my kit on and you will! Probably. I watched a quick preview of next Tues. PBS NOVA - Cave Diving, and the amount of human one set of gear was wearing was puny. >>> When switching regs, I like to keep gas >>> in my lungs seeing as how I'm maintaining my position in the water [quoted text clipped - 14 lines] > > What's a snorkel? ;) I like my snorkel. It allows me to catch my breath w/o inflating my BCD very much after the instructor has thrown all my gear in the water and says, "so, what are you doing on the boat?" >> As I descend the descent rate seems to increase. I attribute this to >> the BCD (lord know what else) being compressed (even if "empty" there [quoted text clipped - 11 lines] > I never ever go down head first. Good way to get air/gas trapped in > the feet of your dry suit. I'll keep that in mind. But for the diving I'm likely to do for the next few years will likely not require more than a wet suit (For my recent dives I did not use a wet suit - I have that built in). I just like to see where I'm going. Signaturegmail originated posts are filtered due to spam. On Feb 7, 7:19 am, Alan Browne <alan.bro...@FreelunchVideotron.ca> wrote: > I'll keep that in mind. But for the diving I'm likely to do for the > next few years will likely not require more than a wet suit (For my > recent dives I did not use a wet suit - I have that built in). I just > like to see where I'm going. Why didn't you say so? No wonder you're sucking so much air. "Insulated" or not, and even if you think you feel warm compared to how you feel back home in the Great White North, your body is still going to be working harder subconsciously against the cold environment - "cold" to the body is water below around 92 degrees and I doubt the ocean water was that warm where you were. Even if you think you don't need it, wear a thin wetsuit. Your body will show its appreciation by giving you longer bottom times and you'll have the added benefit of increased protection from the various stinging critters that patrol the deep. > On Feb 7, 7:19 am, Alan Browne<alan.bro...@FreelunchVideotron.ca> > wrote: [quoted text clipped - 14 lines] > increased protection from the various stinging critters that patrol > the deep. Okay. Next trip I'll add a wet suit. If it increases bottom time, it will be worth it. This was mentioned earlier in the thread. Signaturegmail originated posts are filtered due to spam. On Sat, 06 Feb 2010 19:49:29 -0500, Alan Browne On Sat, 06 Feb 2010 >(On one dive I landed butt first about 2 meters from a sea urchin. From >then on I said, "To hell with PADI, from now on I go down head first."). If your butt was the first body part to hit the bottom, you were doing something unusual. Going down head first takes more energy and reduces your vision. Plus, if you want to slow down your descent for some reason (trouble equalizing for example), you can't use your fins to slow yourself down. How did PADI tell you to descend? > On Sat, 06 Feb 2010 19:49:29 -0500, Alan Browne On Sat, 06 Feb 2010 > [quoted text clipped - 3 lines] > If your butt was the first body part to hit the bottom, you were doing > something unusual. What part of "Newbie" are you having difficulty with? ;-) > Going down head first takes more energy and reduces your vision. > Plus, if you want to slow down your descent for some reason (trouble > equalizing for example), you can't use your fins to slow yourself > down. Not sure how headfirst reduces my vision. My a.s does not have eyes. I get the slow down bit, but going down I can level out very quick - and I don't have trouble with eq. (so far). By head first I don't mean pure vertical (though that doesn't bother me) but a diagonal. As to energy, it seems a near free ride once I get the air out of the BCD. > How did PADI tell you to descend? PADI Book: feet first. Instructor: feet first. Instructor: oh, head first? Sure. Signaturegmail originated posts are filtered due to spam. On Sun, 07 Feb 2010 10:40:47 -0500, Alan Browne >Not sure how headfirst reduces my vision. My a.s does not have eyes. When you are going down head first, you have a good view of what's below you if you arch your back and look down. You have a very poor view of anything else. If your buddy is having difficulty, you won't know. If there are dolphins or fish swimming around in mid water, you'll miss them. > On Sun, 07 Feb 2010 10:40:47 -0500, Alan Browne >> Not sure how headfirst reduces my vision. My a.s does not have eyes. > > When you are going down head first, you have a good view of what's > below you if you arch your back and look down. You mean feet first? Head first I see fine where I'm going. > You have a very poor view of anything else. If your buddy is having > difficulty, you won't know. If there are dolphins or fish swimming > around in mid water, you'll miss them. Good points, but I have a strong sense of wanting to see where I'm going v. bending my head down. Signaturegmail originated posts are filtered due to spam. On Sun, 07 Feb 2010 11:49:44 -0500, Alan Browne >You mean feet first? Head first I see fine where I'm going. If I meant feet first I would have said feet first. In any event, how you dive is up to you. If you dive again you'll see for yourself whether anything anyone has said to you is true. >On Sun, 07 Feb 2010 11:49:44 -0500, Alan Browne >>You mean feet first? Head first I see fine where I'm going. [quoted text clipped - 3 lines] >In any event, how you dive is up to you. If you dive again you'll see >for yourself whether anything anyone has said to you is true. I used to go down head first but that was corrected after my first tech training dive. Now I drop more knee first. I'm more at a 60 degree angle with my feet above my knees...basically forming a V at the knees I have a tendency to drop at an slight angle backwards (meaning that if I'm dropping down a vertical line in a quarry, I tend to keep moving further away from the line instead of going straight down) but I correct that with a couple of fin kicks every once in awhile. O \ _ \/ >>On Sun, 07 Feb 2010 11:49:44 -0500, Alan Browne >>>You mean feet first? Head first I see fine where I'm going. [quoted text clipped - 6 lines] > I used to go down head first but that was corrected after my first > tech training dive. I always drop in a skydiving position, horizontal, with arms and legs out. I drop fully negative, right off the boat. Bottom time is what most of us want. > Now I drop more knee first. I'm more at a 60 > degree angle with my feet above my knees...basically forming a V at [quoted text clipped - 7 lines] > \ _ > \/ Signature-- Popeye "If one does as God does enough times, one will become as God is." -Dr. Hannibal Lector. www.finalprotectivefire.com http://picasaweb.google.com/Popeye8762 On Mon, 8 Feb 2010 03:06:01 -0500, "Douglas W. \"Popeye\" Frederick" <Popeye8762@gmail.com> wrote in rec.scuba: >>>On Sun, 07 Feb 2010 11:49:44 -0500, Alan Browne >>>>You mean feet first? Head first I see fine where I'm going. [quoted text clipped - 12 lines] > > Bottom time is what most of us want. Off a boat my wing is fully inflated so that I can come back up and grab the granny line in a current or to swim back to the boat and wait for my dive buddy. > > I drop fully negative, right off the boat. > [quoted text clipped - 3 lines] > grab the granny line in a current or to swim back to the boat and wait > for my dive buddy. Forget about buddies, I do the same and wait for my camera. >>> I drop fully negative, right off the boat. >> [quoted text clipped - 5 lines] > > Forget about buddies, I do the same and wait for my camera. I think I intend to do (did on my last few dives) the opposite - last man down but sink fast. Just 'cause I'm the airhog. Signaturegmail originated posts are filtered due to spam. > On Mon, 8 Feb 2010 03:06:01 -0500, "Douglas W. \"Popeye\" Frederick" > <Popeye8762@gmail.com> wrote in rec.scuba: [quoted text clipped - 20 lines] > grab the granny line in a current or to swim back to the boat and wait > for my dive buddy. Most of the boats I dive aren't equipped with either. :-) Signature-- Popeye "If one does as God does enough times, one will become as God is." -Dr. Hannibal Lector. www.finalprotectivefire.com http://picasaweb.google.com/Popeye8762 >> On Sun, 07 Feb 2010 11:49:44 -0500, Alan Browne >>> You mean feet first? Head first I see fine where I'm going. [quoted text clipped - 16 lines] > \ _ > \/ Looks like prayer. ... Which may be appropriate! I'll keep that in mind. It has the advantage, even (especially) drifting backwards of presenting a good view of downstination. Signaturegmail originated posts are filtered due to spam. > On Sun, 07 Feb 2010 11:49:44 -0500, Alan Browne >> You mean feet first? Head first I see fine where I'm going. > > If I meant feet first I would have said feet first. Feet first I can't see everything below me as well as head first. That should be pretty obvious. > In any event, how you dive is up to you. If you dive again you'll see > for yourself whether anything anyone has said to you is true. Not a question of "if" but "when". I'm sure everyone has given me rich, full, experienced advice that is as true as it can be. Now I need to apply that experience and adapt. My immediate goals, however, are really to reduce energy expenditure for the sake of air endurance. That tends to focus on how I swim at depth and how I react to things eg: "oh, look at the pretty..." and immediately swim to it w/o taking in everything in my immediate vicinity on the way there. eg: relax and enjoy the journey not just the various destinations. Signaturegmail originated posts are filtered due to spam. > On Sat, 06 Feb 2010 19:49:29 -0500, Alan Browne On Sat, 06 Feb 2010 > [quoted text clipped - 10 lines] > > How did PADI tell you to descend? And why don't either of you have BCs? Those are really useful to slow down descents even without fins. >> On Sat, 06 Feb 2010 19:49:29 -0500, Alan Browne On Sat, 06 Feb 2010 >> [quoted text clipped - 13 lines] >And why don't either of you have BCs? Those are really useful to slow >down descents even without fins. I was taught (and eventually learned proficiency in) only deflating the BC enough to begin feet-first descent. Once you are descending you are negatively buoyant and increasingly less buoyant as all the air spaces compress. Not over-deflating saves you a bit of air when you adjust for neutral at your bottom. I like to trim out and get neutral _before_ crashing the reef. Nothing worse than getting a dirty look from your guide because you crashed the reef, his bread and butter. Scuba-kneeling in class creates a bit of a bad habit IMO, since from the beginning you are taught to crash bottom and wait for the instructor and the other students. Fortunately, it's easily unlearned. If they could emphasize one thing better in class, it would be buoyancy control before hitting bottom but eventually you can become proficient at it without having to do the basic exercise like the fin pivot. Since you previously mentioned breath control as a factor in controlling your depth I can tell you are on the right path. Finding the ideal weighting for your gear profile is also more efficient. Newbs tend to over-weight, I know I did. The only time I was ever close to underweight was on a cold So. Cal. dive where I simply couldn't descend feet first on deflation. I had to invert and kick my way down along the anchor line to catch up to my buddy where he gave me a two pound rock to carry for a while. Once all the air was squeezed out of my wetsuit and hood I was OK, even on ascent. Finding the right amount of weight to carry is made a little more complex when you are using rental gear or going from warm to cold water dives and not having the experience to know on the first dive of the day how much weight you need. > >And why don't either of you have BCs? Those are really useful to slow > >down descents even without fins. [quoted text clipped - 6 lines] > _before_ crashing the reef. Nothing worse than getting a dirty look > from your guide because you crashed the reef, his bread and butter. Even if the negatively buoyant diver manages to slow his ascent and use his fins to avoid crashing into the reef, those fins can still wreak havoc on soft corals and kick up sand and ruin visibility. Lack of awareness of what one's fins are doing is unfortunately very pervasive among divers; I've seen many a dive "pro" (i.e. instructor/ DM, professional video/photographer) kicking the crap out of the reef without even knowing they were doing it - unless they were so callous they were doing it deliberately! >>> And why don't either of you have BCs? Those are really useful to slow >>> down descents even without fins. [quoted text clipped - 15 lines] > without even knowing they were doing it - unless they were so callous > they were doing it deliberately! Another reason I prefer head first. I can arrive pretty neutral (more or less) at about 3 - 5 feet off bottom w/o touching. Within a few breath cycles I know if I need to add some air to the BCD - or pick up a rock (haven't done that though). If I go feet first I'm more likely to misjudge my height off bottom. Signaturegmail originated posts are filtered due to spam. > I was taught (and eventually learned proficiency in) only deflating > the BC enough to begin feet-first descent. Once you are descending you [quoted text clipped - 3 lines] > _before_ crashing the reef. Nothing worse than getting a dirty look > from your guide because you crashed the reef, his bread and butter. If you have air left in your BC when you start descent, you are probably overweighted. If you start sinking easily with a wetsuit on, you are probably overweighted. Wetsuits tend to trap air and it usually takes a bit of fidding to get it out, or one simply fins down a few feet. You do typically have 3-4 more lbs of air than you will on the way back up (for a typical recreational dive - the tech guys may have a lot more) so it's not too hard to get down, but if it's "vent and sink" there's probably room for improvement. > Scuba-kneeling in class creates a bit of a bad habit IMO, since from > the beginning you are taught to crash bottom and wait for the > instructor and the other students. Fortunately, it's easily unlearned. More than a bit of one, and some folks don't seem to unlearn. Can also create a "crutch" pattern - you learn skills such as mask clearing while sitting on the bottom, and since it's difficult for a class to practice those skills in midwater, some people never pick up on performing the same skills in midwater...simply being able to hang in place is a very good thing to learn/practice. > Finding the ideal weighting for your gear profile is also more > efficient. Newbs tend to over-weight, I know I did. The only time I [quoted text clipped - 7 lines] > not having the experience to know on the first dive of the day how > much weight you need. ...and when you over-weight, you then end up pushing an over-inflated BC through the water, which makes you burn more air. Usually throws body position off as well, burning yet more air. I have drastically reduced the amount of weight I "need" since I was a newbie as well - nearly everyone who pays attention does. Then there are the folks who think they "need" 35 lbs, even when diving in skinny suits, because they needed that when learning to dive in thick suits. So long as you are using wetsuits, you can get very nearly correct by bundling up the wetsuit and tossing it in the rinse tank tied up with a weightbelt. When it sinks, you're there. If using an AL80, add 2-3 lbs for the floaty tank. Of course, that means you have to put on a dank wetsuit. To be picky, you should use salt water, not the rinse tank, but the salt water in reach of the dive shop is usually nasty, and the fresh water will get you in the right ballpark. Otherwise, simply get in the habit of checking at the end of each dive, while you are at the safety stop (assuming you bother with such things, as our newbie mostly didn't, thanks to his instructor). Let all the air out of your BC. Don't fin. Your tank is down and thus more buoyant than a full one. Do you stay put, sink, or float at 10-15 feet? If you sink, take out 2 lbs before the next dive. If you float, add 2 lbs. If you stay put, you're good, leave it alone. This is far more accurate than the "bobbing at eye level" foolishness with a full tank on, but does require that you get through a dive first. Expect to be overweight the first couple of times. DOn't overdo, either. It's better to be SLIGHTLY heavy than slightly light, so you can do your safety stop without having to swim down all the time; But only slightly. Despite the evident fact that our newbie was suitless and (I think, not going back over the whole thread to look) also mentioned considerable lead (out of curiosity, how much?) BC and people are nearly neutral - even well-padded people. Tanks will sink or float to a greater or lesser degree depending on the tank, and how much air is in it. Go out in a swimming pool, gearless, exhale fully, and almost everyone sinks. Of those that don't sink, most are not exhaling fully. A few may need a pound or two to sink. As an example of how overweight some folks typically dive, one time at Pickles (all of 18 feet, so you'll be pretty darn buoyant) I picked up a weight pouch with 8 lbs of lead in it. The guy who lost it was on our boat. He didn't even know he had lost it until I asked if anyone had lost one - dropping half his weight didn't result in a decided tendency to surface when at 18 feet; he was carrying _way_ too much. SignatureCats, coffee, chocolate...vices to live by On Feb 7, 11:17 am, Ecnerwal <MyNameForw...@ReplaceWithMyVices.Com.invalid> wrote: > first couple of times. DOn't overdo, either. It's better to be SLIGHTLY > heavy than slightly light, so you can do your safety stop without having > to swim down all the time; But only slightly. Forget about the safety stop, which is optional after all. It's the ascent from the safety stop that should be the slowest part of the diver's total ascent since that's where the greatest pressure differential is occurring, hence the most likely time that nitrogen bubbles will become problematic. If one is already positively buoyant at the safety stop, it's going to be very hard to make a properly slow ascent to the surface without a line to hold onto. Personally, I like to have my BC empty when neutral at the safety stop, then ascend using only my breathing pattern: inhale a bit to slowly start the ascent, then exhale to slow the ascent and prevent lung damage. Done right, and if the seas are mild enough, it's possible to "inch" one's way up to the surface without using inflator or fins, as slowly as anyone could do up a line. > On Feb 7, 11:17 am, Ecnerwal > <MyNameForw...@ReplaceWithMyVices.Com.invalid> wrote: [quoted text clipped - 8 lines] > differential is occurring, hence the most likely time that nitrogen > bubbles will become problematic. <snip> That's the greatest *volume* differential. The *pressure* differential is about .445 PSI per foot (1 ATM/33 FSW) no matter which foot we're talking about, whether it's the deepest or the shallowest of the dive. (This is an incredibly frequent mistake in the trade press and causes many people no end of confusion.) SignatureJohn Eells >> On Feb 7, 11:17 am, Ecnerwal >> <MyNameForw...@ReplaceWithMyVices.Com.invalid> wrote: [quoted text clipped - 17 lines] > shallowest of the dive. (This is an incredibly frequent mistake in the > trade press and causes many people no end of confusion.) It's the greatest Haldanian differential, and that's the only thing that counts. You can ascend from 500 fsw to 233 fsw in one straight shot (deep stop guys forgive me), but ya can't ascend from 233 fsw to the surface without multiple stops. What he said was correct: "It's the ascent from the safety stop that should be the slowest part of the diver's total ascent since that's where the greatest pressure differential is occurring, hence the most likely time that nitrogen bubbles will become problematic." There's a few nits to pick there, but the spirit is correct. esg >>> On Feb 7, 11:17 am, Ecnerwal >>> <MyNameForw...@ReplaceWithMyVices.Com.invalid> wrote: [quoted text clipped - 31 lines] > > esg Mike, I agree with Greg's conclusion completely (which I should have said, and didn't). I don't agree with how he got to it. Any differential pressure will increase and decrease as a linear function of depth, while bubble size is not a linear function of depth. If you still disagree, care to show me the math? I'm willing to learn, if I'm wrong. Show me. Also, V-Planner, used to plan a bounce dive to 500 FSW (one minute of bottom time on 8/80 trimix) thinks the first stop should be at 320', and that there should be nine stops a minute apart between there and 230', though one could argue that it really means a 10 FPM ascent to 220', I suppose. Care to comment? SignatureJohn Eells > Mike, I agree with Greg's conclusion completely (which I should have > said, and didn't). I don't agree with how he got to it. > > Any differential pressure will increase and decrease as a linear > function of depth, while bubble size is not a linear function of depth. If all those fancy words basically mean that the closer you get to the surface, the slower your ascent rate should be, and that stops are just simplified "points on a curve" that approximate what would otherwise be painfully slow ascent rates from stop to stop, then I agree with me too. All I meant, or think I meant, is that all of these recreational dive agencies put so much emphasis on the safety stop and slow ascent rate at depth, but: (1) It's rare that I see a recreational diver that takes even a full 30 seconds to ascend from the 15' stop (as the currently preached 30fpm ascent rate should dictate) as most will pop up from the 15' stop in 5-10 seconds; and (2) If the 30fpm ascent rate is adjudged the "safe" ascent rate from 60 (PADI OW max depth) to the 15' stop, then 30fpm is probably still too fast for the final 15' - taking an entire minute or more for that last 15' would be healthier still (assuming compliant surface conditions). Of course Mike will argue that statistically there's no difference, hence it can't really be "healthier", but there's still that issue of microbubbles that make nitrox divers and those who do deep stops anecdotally "feel better" after a dive than the rest. Don't call it a "safety margin" then, but how's about a "feel better" margin? >(1) It's rare that I see a recreational diver that takes even a full >30 seconds to ascend from the 15' stop (as the currently preached >30fpm ascent rate should dictate) as most will pop up from the 15' >stop in 5-10 seconds; and And what percentage of these divers get bent or embolize? >>(1) It's rare that I see a recreational diver that takes even a full >>30 seconds to ascend from the 15' stop (as the currently preached >>30fpm ascent rate should dictate) as most will pop up from the 15' >>stop in 5-10 seconds; and > > And what percentage of these divers get bent or embolize? And here we have a student that actually understands the problem. esg > >>(1) It's rare that I see a recreational diver that takes even a full > >>30 seconds to ascend from the 15' stop (as the currently preached [quoted text clipped - 4 lines] > > And here we have a student that actually understands the problem. You know I understand as well, I just disagree. Statistically, they're just as "safe" to be sure - that's a binary world of bent or not bent. But, between my ultra-slow ascents and judicious use of nitrox, I find I can stay up later, out drink but a large margin, and still manage to wake up earlier than most lazy liveaboarders on an intensive dive schedule, even those years younger than me and in better shape. Or maybe it's all the spinach I eat, I dunno! >> >>(1) It's rare that I see a recreational diver that takes even a full >> >>30 seconds to ascend from the 15' stop (as the currently preached [quoted text clipped - 12 lines] > intensive dive schedule, even those years younger than me and in > better shape. Or maybe it's all the spinach I eat, I dunno! "Guns are bad. Spinach is good". You heard it here first... :-) Signature-- Popeye "If one does as God does enough times, one will become as God is." -Dr. Hannibal Lector. www.finalprotectivefire.com http://picasaweb.google.com/Popeye8762 > (1) It's rare that I see a recreational diver that takes even a full > 30 seconds to ascend from the 15' stop (as the currently preached [quoted text clipped - 6 lines] > last 15' would be healthier still (assuming compliant surface > conditions). During my course, and through the PADI manual, there is no mention of 30 fpm or less for the last 15' (safety stop or not). The only rate mentioned, ad nauseum, is 60 fpm. Post PADI, the only time we did a safety stop was after a dive to 110'. After the 3 minutes, I just popped a tiny blast into the BCD and rode it up slowly. No idea what the rate was but probably between 30 and 60 fpm. I really need to write a pre-dive checklist for next time to remind me of these things before I go into the water. Signaturegmail originated posts are filtered due to spam. >Post PADI, the only time we did a safety stop was after a dive to 110'. > After the 3 minutes, I just popped a tiny blast into the BCD and rode >it up slowly. No idea what the rate was but probably between 30 and 60 fpm. Don't make a habit out of that. If you review the theory portion of your course, you should understand. On Feb 16, 12:49 pm, Alan Browne <alan.bro...@FreelunchVideotron.ca> wrote: > During my course, and through the PADI manual, there is no mention of 30 > fpm or less for the last 15' (safety stop or not). The only rate > mentioned, ad nauseum, is 60 fpm. I'm not sure why PADI is a holdout, unless they think trying to train a 30 fpm ascent rate is too difficult. TDI, "A Diver's Guide to Decompression Procedures", (c) 2000: "In the case of the USN tables, ascent is defined as a rate of 30 feet per minute (fpm). . . . Decompression procedures are fairly straightforward once the time and depth stops are known. The diver ascends to the first stop at the specific rate, typically 30 feet per minute. 30 feet per minute means 20 seconds for each 10 FSW, which may seem terribly slow." NASDS, "Open Water", (c) 1995: "Do not [sic] ascent faster than 30 feet per minute - use your time and depth monitors to check your rate of ascent . . . Slow your ascent at 30 feet and take 3 to 5 minutes to reach the surface from 30 feet" SSI, "Dive Control Specialist Manual", (c) 1993: "Be sure to emphasize the the importance of the slow ascent rate of 30 feet (9 [sic] metres) per minute and a safety stop of 3-5 minutes at 15 feet (5 [sic] metres)." Do YMCA, NAUI, IANTD and the others recommend 30 or 60 feet? Why does PADI stick with 60 fpm? > On Feb 16, 12:49 pm, Alan Browne <alan.bro...@FreelunchVideotron.ca> > wrote: [quoted text clipped - 26 lines] > Do YMCA, NAUI, IANTD and the others recommend 30 or 60 feet? Why does > PADI stick with 60 fpm? The USN full dress ascent rate is slow because full dress encloses a huge volume and the risk of "blowing up" is very real and very dangerous. The slow rate gives the diver sufficient time to manage his buoyancy. Scuba divers have no such problem (except those that put air in their BCDs, who deserve to die horrid painful deaths anyway) and the ascent rate is (should be) set to minimize the risk of embolism or lung overexpansion. 60 fpm, except the last 2 or 3 fathoms, is sufficiently slow for the competent diver. esg 60 fpm > > On Feb 16, 12:49 pm, Alan Browne <alan.bro...@FreelunchVideotron.ca> > > wrote: [quoted text clipped - 39 lines] > 60 fpm, except the last 2 or 3 fathoms, is sufficiently slow for the > competent diver. Hmm, aren't those very same well-trained Navy divers also strapping young men in tip-top shape? And since the table's stops are based on 30 fpm ascents, wouldn't 60 fpm ascents necessarily lengthen the indicated stop times in order to safely decompress? >>>Do YMCA, NAUI, IANTD and the others recommend 30 or 60 feet? Why does >>>PADI stick with 60 fpm? [quoted text clipped - 16 lines] > 30 fpm ascents, wouldn't 60 fpm ascents necessarily lengthen the > indicated stop times in order to safely decompress? When they're ascending, they're tired, sore, and cold. Managing inflation of a full dress on ascent has little to do with age or strappingness. The slower the ascent, the greater the deco time at any stop, true. It's a trade-off. esg > On Feb 16, 12:49 pm, Alan Browne<alan.bro...@FreelunchVideotron.ca> > wrote: [quoted text clipped - 26 lines] > Do YMCA, NAUI, IANTD and the others recommend 30 or 60 feet? Why does > PADI stick with 60 fpm? I'm not arguing that PADI is "right". But that is what they train. However the data I gave above is from the "PADI OPEN WATER DIVER MANUAL" which is for 60' or less depth. Perhaps in their "deep" diving course they change the rates? That would seem like a bad overall system approach. So I don't really know where PADI take this. Signaturegmail originated posts are filtered due to spam. On Feb 17, 1:08 pm, Alan Browne <alan.bro...@FreelunchVideotron.ca> wrote: > Perhaps in their "deep" diving course they change the rates? That would > seem like a bad overall system approach. So I don't really know where > PADI take this. Don't feel too bad. PADI probably doesn't know either. 60 or 30 for your ascent to your safety stop from recreational depth probably won't make a difference whether you live or die. Personally, I believe, and maybe it's only the kind of "faith" that others reserve for a deity, that 30 is better for me, and even slower in the last 15' or so. You won't die following PADI's recommendations, but at least give my way a try sometime and see if you feel more energetic post-dive. It certainly can't hurt. > On Feb 17, 1:08 pm, Alan Browne<alan.bro...@FreelunchVideotron.ca> > wrote: [quoted text clipped - 11 lines] > try sometime and see if you feel more energetic post-dive. It > certainly can't hurt. I'll keep that in mind. I'm adding notes to my PADI manual for the next trip when I review. Signaturegmail originated posts are filtered due to spam. > I'll keep that in mind. I'm adding notes to my PADI manual for the next > trip when I review. Something else to keep in mind is that PADI was strongly on record that Nitrox was the "Evil VooDoo Gas" that should be avoided by all recreational divers ... front page Editorials in _Skin Diver_ magazine, etc, etc. ...until they realized that Nitrox was a way to make money. Today, one can get a shiny Nitrox C-Card concurrent at the same time as your PADI OW card, at a "minimal additional fee". -hh >> I'll keep that in mind. I'm adding notes to my PADI manual for the next >> trip when I review. [quoted text clipped - 8 lines] > Today, one can get a shiny Nitrox C-Card concurrent at the same time > as your PADI OW card, at a "minimal additional fee". ;-) Next PADI boyscout badges will probably be "wreck", "photo" and "night" (perhaps "navigation" too). (I have done one wreck (sort of) and a night dive. Not sure if my sole dive to 110' qualifies for the "deep" boyscout badge. I suspect I can do all three in a two week vacation and add on another one according to local conditions. (eg: "drift" perhaps). Signaturegmail originated posts are filtered due to spam. > On Feb 17, 1:08 pm, Alan Browne <alan.bro...@FreelunchVideotron.ca> > wrote: [quoted text clipped - 11 lines] > try sometime and see if you feel more energetic post-dive. It > certainly can't hurt. http://www.diversalertnetwork.org/news/Article.aspx?newsid=514 Ascent Rates: A Quick History Historical guidelines as to rates of ascent are pertinent. In the 19th century, for example, the French physiologist Paul Bert in 1878 quoted rates of 3 feet per minute and the English physiologist John Scott Haldane in 1907 recommended ascent rates between 5 and 30 feet (1.5 and 9 meters) per minute. From 1920-1957, rates of 25 feet (7.5 meters) per minute were recommended. Then in 1958, during the production of the U.S. Navy Diving Manual, the rate of ascent to be proposed came under review. Cdr. Francis Douglas Fane of the U.S. Navy West Coast Underwater Demolition Team wanted rates for his frogmen of 100 feet (30 meters) per minute or faster. The hardhat divers, on the other hand, considered this impractical for the heavily suited divers who were used to coming up a line at 10 feet (3 meters) per minute. Thus, a compromise was reached at 60 feet (18 meters) per minute, which was also a convenient 1 foot per second. So from 1957 until 1993 the U.S. Navy tables have consistently advocated an ascent rate of 60 feet per minute, based on this purely empirical decision, with many recreational diving tables and even early computers following suit. In recent years this has been slowed to 30 feet per minute with a recommended safety stop for three to five minutes at 15-20 feet (4.5-6 meters). However, this still brings the diver quite rapidly to the surface, often after some 30-60 minutes at depth. Hi Greg, > Of course Mike will argue that statistically there's no difference, > hence it can't really be "healthier", but there's still that issue of > microbubbles that make nitrox divers and those who do deep stops > anecdotally "feel better" after a dive than the rest. Don't call it a > "safety margin" then, but how's about a "feel better" margin? Well, it actually _is_ statistically a big difference. It is cutting "undeserved hit" for about 60% as we discussed before. It is reducing microbubbles to almost nill, wether they may cause problems or don`t. It is recommendation of RSTC and DAN. It is mesurable. It leads to high ascent rates combined with/AND deep stops, and very slow ascent rate at shallow 15ft waters. It is what many divers already do by expirience lg joerg SignatureDie neuen Knips-Fotos aus dem Urlaub: http://www.notabstieg.de/maledives-4-2009/index.html http://www.grabmalkultur.de Hi Greg, > If all those fancy words basically mean that the closer you get to the > surface, the slower your ascent rate should be, and that stops are > just simplified "points on a curve" that approximate what would > otherwise be painfully slow ascent rates from stop to stop, then I > agree with me too. The only difference between the to is at very slow ascent rates without stops the degassing process does not start efficiently. So faster ascent rates combined with stops maximize the offgassing process in your body. Research is showing that even for rec NDL purpose ascents like these are better: \ ------------/ \ / \ ------- \ / \ / \ ---- \ / \ / \---- > All I meant, or think I meant, is that all of these recreational dive > agencies put so much emphasis on the safety stop and slow ascent rate > at depth, but: No they don`t all. RSTC is recommending deep stops and fast rates in depth and slow rates in shallow. It is just that PADI and SSI did not introduct this yet. > (1) It's rare that I see a recreational diver that takes even a full > 30 seconds to ascend from the 15' stop (as the currently preached > 30fpm ascent rate should dictate) as most will pop up from the 15' > stop in 5-10 seconds; and Yes, this is bad. Because many do and they don`t get hurt doesn`t mean it is good behaviour. > (2) If the 30fpm ascent rate is adjudged the "safe" ascent rate from > 60 (PADI OW max depth) to the 15' stop, then 30fpm is probably still > too fast for the final 15' - taking an entire minute or more for that > last 15' would be healthier still (assuming compliant surface > conditions). 1 min minimum. better 2 or 3. > Of course Mike will argue that statistically there's no difference, > hence just take the profile out of your DC into PC. It shows assumed values for each tissue. The values explode on the last 9ft ascent. lg joerg it can't really be "healthier", but there's still that issue of > microbubbles that make nitrox divers and those who do deep stops > anecdotally "feel better" after a dive than the rest. Don't call it a > "safety margin" then, but how's about a "feel better" margin? SignatureDie neuen Knips-Fotos aus dem Urlaub: http://www.notabstieg.de/maledives-4-2009/index.html http://www.grabmalkultur.de On Feb 7, 2:17 pm, Ecnerwal <MyNameForw...@ReplaceWithMyVices.Com.invalid> wrote: > If you have air left in your BC when you start descent, you are probably > overweighted. If you start sinking easily with a wetsuit on, you are [quoted text clipped - 4 lines] > not too hard to get down, but if it's "vent and sink" there's probably > room for improvement. If you are diving with something compressible then it's common to have to dump all air to get down. The compression of a neoprene wetsuit relieves buoyancy so you can stay at a safety stop when you have used up that 3 or 4 lbs of air. Here is one situation where descending without needing to fully vent a BC is required: I've recently been diving without a wetsuit. I did a weight check and put on just enough weight to get down. Since I didn't have anything compressible my descent didn't accelerate and I only needed a short burst of air in the BC when I reached depth. After 20 minutes of using a couple of pounds of air I couldn't stay down despite dumping my BC fully. I added 4 lbs of lead for the next dive. > More than a bit of one, and some folks don't seem to unlearn. Can also > create a "crutch" pattern - you learn skills such as mask clearing while > sitting on the bottom, and since it's difficult for a class to practice > those skills in midwater, some people never pick up on performing the > same skills in midwater...simply being able to hang in place is a very > good thing to learn/practice. I've thought that a course on buoyancy, trim and finning techniques would be great for beginners. I hacked my way through that over many dives dealing with bad buoyancy and kicking up silt. The tech courses do this in their first class. I would have liked to have some guidance early on. > ...and when you over-weight, you then end up pushing an over-inflated BC > through the water, which makes you burn more air. Usually throws body [quoted text clipped - 3 lines] > they "need" 35 lbs, even when diving in skinny suits, because they > needed that when learning to dive in thick suits. Trim is another big one. A lot of divers fin to keep buoyant. Not only do they kick up silt but they go through air faster. I've found proper trim to be a better way to reduce drag than an overinflated BC. > So long as you are using wetsuits, you can get very nearly correct by > bundling up the wetsuit and tossing it in the rinse tank tied up with a [quoted text clipped - 3 lines] > the salt water in reach of the dive shop is usually nasty, and the fresh > water will get you in the right ballpark. All the literature says to get neutral in the water and add 5 lbs for the air in the tank. I would have thought that balancing a wet suit then only adding 3 lbs would still make a diver light by a couple of pounds. > Otherwise, simply get in the habit of checking at the end of each dive, > while you are at the safety stop (assuming you bother with such things, [quoted text clipped - 24 lines] > lost one - dropping half his weight didn't result in a decided tendency > to surface when at 18 feet; he was carrying _way_ too much. Weight checks can be inconvenient, whether it's a boat dive or a shore dive. I make it more convenient by arranging one with a buddy at the beginning of a dive. I keep 2 or 4 lbs of lead in a BC pocket and hand it to the buddy on the surface. If I can't descend then I know I've reached a limit. If I can then I'll take it off next dive. Either way the buddy hands the lead back and I dive with it that dive, making my adjustment the next dive. For new divers like this one. He will be anxious on the first dive, will keep more air in his lungs and will need more lead than on subsequent dives. I'm, not a new diver, but I know I'll be anxious on swift current dives (that are not drift dives) or cold ice dives so I add a couple of lbs to compensate. > On Sat, 06 Feb 2010 19:49:29 -0500, Alan Browne On Sat, 06 Feb 2010 > [quoted text clipped - 3 lines] > If your butt was the first body part to hit the bottom, you were doing > something unusual. I'd say he's a bit cocked up if he's hitting the sea floor at -all-. > Going down head first takes more energy and reduces your vision. I don't understand that at all. I sink from being negative. Motionless. That doesn't require any energy at all. I descent horizontally. As far as it reducing your vision, aren't we all looking at (or for) the bottom? > Plus, if you want to slow down your descent for some reason (trouble > equalizing for example), you can't use your fins to slow yourself > down. I use my inflator. > How did PADI tell you to descend? Signature-- Popeye "If one does as God does enough times, one will become as God is." -Dr. Hannibal Lector. www.finalprotectivefire.com http://picasaweb.google.com/Popeye8762 On Mon, 8 Feb 2010 03:00:04 -0500, "Douglas W. \"Popeye\" Frederick" <Popeye8762@gmail.com> wrote: >> Going down head first takes more energy and reduces your vision. > > I don't understand that at all. Assuming and maintaining a headdown position takes energy because it's not natural. Most of your buoyancy is in your lungs so, in the absence of any other forces, most divers will assume a head up position in the water. For vision, if you are vertical and head down, you have to bend your head backwards to see the bottom. That's harder than being head up and being able to see the bottom by bending your head forward. > On Mon, 8 Feb 2010 03:00:04 -0500, "Douglas W. \"Popeye\" Frederick" > <Popeye8762@gmail.com> wrote: [quoted text clipped - 11 lines] > head backwards to see the bottom. That's harder than being head up > and being able to see the bottom by bending your head forward. In my head first descents, I do not go vertical, but on a diagonal. The amount that my chin is lifted is quite comfortable - even with my head nominally straight (most repose) I can see where I'm going. Eyeballs do point upish. I hope a newer mask will have even less peripheral (including up) blocking than my current one. Signaturegmail originated posts are filtered due to spam. > On Mon, 8 Feb 2010 03:00:04 -0500, "Douglas W. \"Popeye\" Frederick" > <Popeye8762@gmail.com> wrote: [quoted text clipped - 7 lines] > absence of any other forces, most divers will assume a head up > position in the water. Attitude depends completely on how you're trimmed. > For vision, if you are vertical and head down, you have to bend your > head backwards to see the bottom. That's harder than being head up > and being able to see the bottom by bending your head forward. Yah, if you were vertical inverted. Signature-- Popeye "If one does as God does enough times, one will become as God is." -Dr. Hannibal Lector. www.finalprotectivefire.com http://picasaweb.google.com/Popeye8762 > Yah, if you were vertical inverted. I vote for "butt first" ;-) SignatureDie neuen Knips-Fotos aus dem Urlaub: http://www.notabstieg.de/maledives-4-2009/index.html http://www.grabmalkultur.de >> Yah, if you were vertical inverted. > > I vote for "butt first" > > ;-) \\ :-) Signature-- Popeye "If one does as God does enough times, one will become as God is." -Dr. Hannibal Lector. www.finalprotectivefire.com http://picasaweb.google.com/Popeye8762 <snip> >> I hold my breath underwater from time to time (like when I'm diving >> alone and want to listen for a gas leak) and everytime I switch [quoted text clipped - 4 lines] > > To what advantage? Mixes with less than 16% O2 (called hypoxic mixes), used for deep diving to prevent O2 toxicity, will not keep you conscious at sea level. By holding his breath from the surface to 20', he's making sure he has enough inspired O2 to stay awake until the pressure has risen far enough to make his back gas breathable. I switch from a deco mix to back gas instead. Personal preference. SignatureJohn Eells > <snip> >>>> [quoted text clipped - 9 lines] > Mixes with less than 16% O2 (called hypoxic mixes), used for deep diving > to prevent O2 toxicity, will not keep you conscious at sea level. By See my blatant "I'm really an ignorant Newbie" in my prior post. > holding his breath from the surface to 20', he's making sure he has > enough inspired O2 to stay awake until the pressure has risen far enough > to make his back gas breathable. > > I switch from a deco mix to back gas instead. Personal preference. Color me confused. I'm not there yet. Signaturegmail originated posts are filtered due to spam. >> <snip> >>>>> [quoted text clipped - 19 lines] > >Color me confused. I'm not there yet. This is technical diving. You're not ready for it. "back gas" is the cylinder on your back. Tech divers dive with trimix (N2, O2, He mix) on their back. The mix may vary according to the plan for the dive. The mix will not sustain a diver at sea level but it is sufficient for a range of pressures once descent has begun. N2/O2 (78%/21%) is toxic below recreational depths. Besides nitrogen narcosis, 21% oxygen becomes toxic to your central nervous system as pressure increases. If you ever take Nitrox (EAN) training you will learn this. This is why there is more focus on maximum operating depth (MOD) when diving on EAN. O2 toxicity damage can be permanently damaging or fatal (extremely permanent). Tecs also dive with one or more front bottles, these can be air or pure O2 depending on the plan. Staging bottles may also be available on a down line for deco dives to support the deco stops and ascent. Breath holding is perfectly OK on descent because everything is compressing. Holding it to the point where you accumulate an O2 deficit or CO2 surplus is to be avoided. You don't want to get into the habit of ascending with a closed airway or you run the danger of over-expanding your lungs (pulmonary barotrauma) and gas embolism. > This is technical diving. You're not ready for it. > [quoted text clipped - 9 lines] > (MOD) when diving on EAN. O2 toxicity damage can be permanently > damaging or fatal (extremely permanent). To help clarify both of the above, while we often talk in percentages of a mix, the other major variable is the pressure at which we're going to use the breathing mix at, because its not a "%" that the human body cares about, but the absolute fractional pressure ("partial pressure" = PP, such as PPO2) of that particular gas in the body. For Oxgyen, its bad for the PPO2 to be too low (hypoxia) and its bad for the PPO2 to be too high (toxic). For Nitrogen, higher PPN2's are the factor that goes into our deco tables. As this applies to diving with mixes other than Air, in a nutshell, these are done in order to move the dive profile to a different point within the rules, to gain some benefit. For example, Nitrox has higher O2, which also means lower N2. The higher PPO2 adds a risk of O2 toxicity, which is avoided (minimized) by not going deep...the benefit is a lower PPN2 which results in less N2 ongassing which will minimize our deco / lengthen our bottom time. For the tech example mentioned here, the O2 in the mix was reduced, so that the mix wouldn't be O2 toxic at depth. There was also He added to keep the PPN2 down too, but this isn't germane to this part. The lower PPO2 reduces the risk of O2 toxicity at depth...that's its benefit...but it carries a 'new' risk in that this breathing mix is unsafe at low pressure ... hypoxic. As such, it won't have enough O2 in it to keep you conscious at the surface (1 ATM), so you need to plan to breathe something else...something with a high-enough-O2-for- the-surface. Hope that helps explain the physics & biology. Now in John's case, the way that he's staying good at the surface is breathing an outside gulp of air when at the surface, then holding that breath and rapidly descending to a depth where the higher ambient pressure means that the PPO2 in his tanks is now high enough for it to no longer be hypoxic (bad). The alternative would be to use another regulator/tank with a "good for surface" mix and after descending a similarly short distance down, switch to the low-O2 "bottom mix", since the addition of depth has boosted all of the PP's. Which approach is best (lowest risk) is subject to debate" There is a risk in John's approach in that if his descent is interrupted before he gets deep enough to take a breath off of his 'bottom mix', he will get a hypoxic breath. There's also a risk in that if he aborts his dive for some reason while still relatively shallow, and goes back up to surface, he has to switch regulators to a higher-O2 mix, and forgetting to do so will get him a hypoxic breath. But there's also a benefit to his approach in that he's able to skip doing a regulator switch during a normal descent, because if he forgets to do that switch on the way down, he can have too much O2 (toxic) due to being on the wrong mix for deep. Since all gas switches technically carry some risk of getting them wrong, a technique which results in one fewer gas swap can be considered a risk reduction too. -hh >> This is technical diving. You're not ready for it. >> [quoted text clipped - 15 lines] > human body cares about, but the absolute fractional pressure ("partial > pressure" = PP, such as PPO2) of that particular gas in the body. I do remember my HS chemistry class, the notion of PP was clear enough. > For Oxgyen, its bad for the PPO2 to be too low (hypoxia) and its bad > for the PPO2 to be too high (toxic). [quoted text clipped - 28 lines] > pressure means that the PPO2 in his tanks is now high enough for it to > no longer be hypoxic (bad). Got it. > The alternative would be to use another regulator/tank with a "good > for surface" mix and after descending a similarly short distance down, [quoted text clipped - 6 lines] > interrupted before he gets deep enough to take a breath off of his > 'bottom mix', he will get a hypoxic breath. Better than no breath, perhaps and a signal to press the up button. > There's also a risk in that if he aborts his dive for some reason > while still relatively shallow, and goes back up to surface, he has to > switch regulators to a higher-O2 mix, and forgetting to do so will get > him a hypoxic breath. I don't suppose one would switch to the 0 tank (the atmosphere) ...? > But there's also a benefit to his approach in that he's able to skip > doing a regulator switch during a normal descent, because if he [quoted text clipped - 4 lines] > wrong, a technique which results in one fewer gas swap can be > considered a risk reduction too. Less is usually more. I'm a big fan of visualization of complex tasks ahead and for such diving that would seem necessary. Signaturegmail originated posts are filtered due to spam. > I do remember my HS chemistry class, the notion of PP was clear enough. Good to hear. Unfortunately, the minimum training standards for diving have gotten so watered down over the years, we can't even assume a new poster (no insult intended) has even heard of High School, let alone a science class. > > There's also a risk in that if he aborts his dive for some reason > > while still relatively shallow, and goes back up to surface, he has to > > switch regulators to a higher-O2 mix, and forgetting to do so will get > > him a hypoxic breath. > > I don't suppose one would switch to the 0 tank (the atmosphere) ...? Yes, but that's a tad difficult to do before you actually reach the surface; hence the risk. -hh >> I do remember my HS chemistry class, the notion of PP was clear enough. > [quoted text clipped - 12 lines] >Yes, but that's a tad difficult to do before you actually reach the >surface; hence the risk. Although there really isn't much risk with hypoxic mixtures between 12-16% even at the surface. It's basically the equivalent to breathing air at 14,000 feet with 12% and 11,000 feet with 14%. You're fine unless you're working hard. >>> I do remember my HS chemistry class, the notion of PP was clear enough. >> [quoted text clipped - 17 lines] > breathing air at 14,000 feet with 12% and 11,000 feet with 14%. You're > fine unless you're working hard. Got it. For comparison, IIRC the rules (Canada), pilots in non-press a/c have to don O2 at 10,500 and passengers at 12,500. (I'm probably off a bit on those). Signaturegmail originated posts are filtered due to spam. On Feb 7, 7:29 am, Alan Browne <alan.bro...@FreelunchVideotron.ca> wrote: > > There is a risk in John's approach in that if his descent is > > interrupted before he gets deep enough to take a breath off of his > > 'bottom mix', he will get a hypoxic breath. > > Better than no breath, perhaps and a signal to press the up button. Exactly. Hypoxic does not equal toxic. 15% oxygen won't sustain consciousness, but mixed with the oxygen already in his system, it would probably sustain him for at least a few breaths before passing out. And by the time he's barely reached 5 feet deep, he's already reached a partial pressure over .17 and that is sustainable until he gets even deeper. But there's still a danger that something could happen so near the surface that hypoxia could become a problem. For instance, what if he descended a couple feet only to see a great white shark bearing down on him. Immediate instinct would probably be to swim with reg in mouth away from the shark but if he's breathing hypoxic air and kicking like mad, he'll pass out in no time at all and become shark lunch. Fortunately for John he dives in lakes where great whites aren't found too often and if he does encounter one, hopefully he'll remember to swim down as he's swimming away. > On Feb 7, 7:29 am, Alan Browne<alan.bro...@FreelunchVideotron.ca> > wrote: [quoted text clipped - 21 lines] > aren't found too often and if he does encounter one, hopefully he'll > remember to swim down as he's swimming away. Any situation can be changed with complexity. Maybe the world needs single regulators that, based on pressure (depth), switch over to the proper mix tank. Of course that's more, not less, system complexity and chance of configuration error and system failure. Signaturegmail originated posts are filtered due to spam. >> On Feb 7, 7:29 am, Alan Browne<alan.bro...@FreelunchVideotron.ca> >> wrote: [quoted text clipped - 26 lines] >proper mix tank. Of course that's more, not less, system complexity and >chance of configuration error and system failure. CCRs basically work that way (they regulate the PP of O2 and He). On Feb 7, 8:30 am, Alan Browne <alan.bro...@FreelunchVideotron.ca> wrote: > Any situation can be changed with complexity. Maybe the world needs > single regulators that, based on pressure (depth), switch over to the > proper mix tank. Of course that's more, not less, system complexity and > chance of configuration error and system failure. They already have those, they're called closed-circuit rebreathers. Instead of "switching" over from tank to tank, the electronically- controlled rebreather automatically mixes breathing gas from multiple sources (usually a tank of oxygen and a tank of "diluent" gas which can be air or trimix) "on the fly" to maintain a certain set partial pressure of oxygen. While some of these systems can be made very simple (like the KISS rebreather where you act as the "electronic control" and adjust the breathing gases manually), you're right, they do introduce much complexity and chance of user error and/or system failure, which is why they require much additional training. > "back gas" is the cylinder on your back. Tech divers dive with trimix > (N2, O2, He mix) on their back. The mix may vary according to the plan [quoted text clipped - 17 lines] > the habit of ascending with a closed airway or you run the danger of > over-expanding your lungs (pulmonary barotrauma) and gas embolism. The last part was 101, but the top part interesting. Thanks. Signaturegmail originated posts are filtered due to spam. >> oh. I would have though it's zero sum since I'm taking "surface air" >> with me, not 'pressed. [quoted text clipped - 22 lines] > Take the swim, stay on the surface, get back in the boat and take your > hydration. Pee on the ascent and avoid the extra swim altogether. Thx. But I'll still take the swim! I hate sitting around. Signaturegmail originated posts are filtered due to spam. On Jan 29, 1:10 pm, Alan Browne <alan.bro...@FreelunchVideotron.ca> wrote: > >> oh. I would have though it's zero sum since I'm taking "surface air" > >> with me, not 'pressed. [quoted text clipped - 24 lines] > > Thx. But I'll still take the swim! I hate sitting around. Light exercise can actually help with the offgassing process (just keep it light), and there's no reason why you can't bring a water bottle along with you on your surface snorkle. The idea that a snorkle tube will impair offgassing is simply ludicrous. >On Jan 29, 1:10 pm, Alan Browne <alan.bro...@FreelunchVideotron.ca> >wrote: [quoted text clipped - 32 lines] >bottle along with you on your surface snorkle. The idea that a >snorkle tube will impair offgassing is simply ludicrous. I never said the tube impairs offgassing, being at 20 feet on a free dive does, even if it's only for 30 seconds. You are re-pressurizing and inhibiting dissolution and your computer on the boat doesn't know it. Will it make a difference? I don't know, on some tissues it might. On a five-dive live aboard it might. I know I don't want to test it myself. On tables I'd probably give myself one letter group on a repetitive dive schedule or a longer SIT afterward, but in a group you may not be able to extend the SIT. As an air sucker I liked to be one of the last ones down, then my deficiency was not as sever on the dive and I could ascend with the group. > >Light exercise can actually help with the offgassing process (just > >keep it light), and there's no reason why you can't bring a water [quoted text clipped - 9 lines] > repetitive dive schedule or a longer SIT afterward, but in a group you > may not be able to extend the SIT. I never said you said that. I was referring to this comment from Ecnerwal: "Snorkeling by which you actually mean free diving is a very bad idea - even surface snorkeling is not quite as effective at degassing as being on the surface breathing - the length of the tube makes respiration somewhat inefficient." That's the comment that I found ludicrous. Offgassing at the surface is far more dependent on the pressure differential from the gas absorbed at depth than it dependent on the efficiency of surface respiration. Breathing through a snorkel allows sufficient oxygen to be inhaled and sufficient depressurized nitrogen to be exhaled to effect normal surface offgassing just fine. >> >Light exercise can actually help with the offgassing process (just >> >keep it light), and there's no reason why you can't bring a water [quoted text clipped - 22 lines] >be inhaled and sufficient depressurized nitrogen to be exhaled to >effect normal surface offgassing just fine. Thank you for clarifying that. >> On Jan 29, 1:10 pm, Alan Browne<alan.bro...@FreelunchVideotron.ca> >> wrote: [quoted text clipped - 45 lines] > deficiency was not as sever on the dive and I could ascend with the > group. That was my practice after a few, being last one to begin descent. On a couple dives where there were a lot of first timers going on a "one off" this could mean 5 minutes or more while their individual problems were worked out. Signaturegmail originated posts are filtered due to spam. On Jan 28, 9:40 pm, Alan Browne <alan.bro...@FreelunchVideotron.ca> wrote: > >> I'm quite happy to snorkel (been doing that for a long time) when on the > >> surface. Actually, the boat captain didn't like me much as after I got [quoted text clipped - 13 lines] > oh. I would have though it's zero sum since I'm taking "surface air" > with me, not 'pressed. Imagine that after diving you may have little micro bubbles of nitrogen backing up in the fine capillaries of your lungs. Doing a quick bounce dive (free dive or not) can squeeze those bubbles past your lungs and let them collect somewhere a lot more dangerous like your brain or heart. Spend your surface interval on the surface. Cam On Jan 28, 6:40 pm, Alan Browne <alan.bro...@FreelunchVideotron.ca> wrote: > That I can manage, but I may have PO'd buddies as I signal end-of-dive > earlier than they're ready. Yep, I can certainly sympathize. Common wisdom tells you to not worry about what your buddies might think, that your safety is first and foremost and any buddy should be happy and willing to go along even if you abort after 15 minutes. But practically, sure, it's easy to imagine that a buddy who is planning on making only 10 dives in a week's vacation might be a bit pissed off if one or more of those dives are cut short by an airhog buddy. However, many dive operations will allow one of a buddy pair to surface early and let the other buddy continue following the DM/group - this is best done in a drift dive so it's not necessary to bring the entire group back to the starting point/mooring line. If you're self- conscious about your bottom time, choose these sorts of dive ops on your next trip (you can also research dive ops that provide bigger tanks for air hogs). Your only other alternative is skip-breathing to try to milk the most out of a tank (keeping shallower than the rest of the group helps, but then your buddy will either have to dive shallower too or else risk undue separation), but that tends to cause headaches, something I can relate from plenty of personal experience! > On Jan 28, 6:40 pm, Alan Browne<alan.bro...@FreelunchVideotron.ca> > wrote: [quoted text clipped - 21 lines] > shallower too or else risk undue separation), but that tends to cause > headaches, something I can relate from plenty of personal experience! I tend to like bottom skimming, so I'm the deepest of the pack - and eating air to show it... skip breathing seems to be a big non-no as far as the PADI book went. OTOH, the instructor told me to try that too. In the end I think for a given activity the body want so much O2 and that's all there is to it. Really need to focus on low energy dives. Our instructor was big on "throw the BCD/tank in the water and put it on there." That had two consequences, the first being it's harder to do a buddy check and secondly you spend more energy getting it on and adjusting straps and the like. That meant for me taking a few extra minutes to breathe on the surface so that I wouldn't immediately be chugging air from the tank at a faster rate - nearer the surface, not so bad, but still. (Also led to me descending while still on snorkel - my fault). Signaturegmail originated posts are filtered due to spam. On Jan 30, 6:51 am, Alan Browne <alan.bro...@FreelunchVideotron.ca> wrote: > I tend to like bottom skimming, so I'm the deepest of the pack - and > eating air to show it... skip breathing seems to be a big non-no as far > as the PADI book went. OTOH, the instructor told me to try that too. > In the end I think for a given activity the body want so much O2 and > that's all there is to it. Really need to focus on low energy dives. The problem isn't getting enough O2 out of the tank, it's getting it out of your lungs before you exhale and waste most of it as bubbles. That's why slow deep breathing is even more important underwater. The more alveoli you can expose to oxygen, the less your body will be craving more. Unfortunately, by allowing the oxygen to stick around your lungs longer, you're also allowing CO2 to stick around longer and that can build up and cause a headache. You have to make the cost/ benefit analysis: is a little headache worth an extra 5 minutes underwater? > Our instructor was big on "throw the BCD/tank in the water and put it on > there." That had two consequences, the first being it's harder to do a [quoted text clipped - 4 lines] > bad, but still. (Also led to me descending while still on snorkel - my > fault). That does sound sort of stupid IMO. Sure, in-water donning is a decent exercise to try once or twice. (Doing it at depth is even more useful.) But only once did I ever dive with any sort of dive operation where they had us don in-water and that was because the water was so rough that it was supposedly impossible to help everyone gear up on board, so the dingy driver started chucking people's gear in the water and we had to go after them. It couldn't have been very memorable otherwise, because I can't even remember where that was. Otherwise, the vast, vast, vast majority of dive ops will have the divers gear up on the boat, then backroll or stride (or use some other way) into the water. If you do a shore dive on your own, you'll again most likely gear up on the shore, then walk into the water (some people do this with fins on, but fins are one thing I wait to don until I'm in the water on shore dives). It doesn't make too much sense that your instructor would have people practice getting into the water in manner contrary to how the vast majority of recreational diving is done, but perhaps he had his reasons. > On Jan 30, 6:51 am, Alan Browne<alan.bro...@FreelunchVideotron.ca> > wrote: [quoted text clipped - 14 lines] > benefit analysis: is a little headache worth an extra 5 minutes > underwater? A headache, perhaps not, but if the optimal point can be found, then learning it is worth it. Are you sure your headaches aren't related to the night before ;-) ? >> Our instructor was big on "throw the BCD/tank in the water and put it on >> there." That had two consequences, the first being it's harder to do a [quoted text clipped - 22 lines] > water in manner contrary to how the vast majority of recreational > diving is done, but perhaps he had his reasons. It seemed to be his fetish - I don't even recall him entering the water geared up. On the deep dive (10+ foot swells) I pointedly told him I wanted to be all set on board and roll in backwards. I didn't want a repeat of the fouled hose that I'd had on an earlier in-water donning as the rough water would have made it even worse and tiring to sort out. On both shore dives (incl. at night) we put on the BCD in the water - these were off rocks into a pool of water (2-3 meters). I'd like to try dumping my gear deflated and weighted into about 20-30' of water and seeing how well I could do diving, breathing and donning the eqt. That's one to do with a buddy close at hand... better to have a BCD with integrated weights for that I suppose. At worse, of course just inflate the BCD and ride to the surface but shouldn't be a big deal. Hmm on the way down would I have air to equalize my ears? Signaturegmail originated posts are filtered due to spam. >That I can manage, but I may have PO'd buddies as I signal end-of-dive >earlier than they're ready. Buy them a beer to make it up to them. They'll get over it. >> That I can manage, but I may have PO'd buddies as I signal end-of-dive >> earlier than they're ready. > > Buy them a beer to make it up to them. They'll get over it. Beer doesn't seem to be enough to me. What's the minute-depth to beer exchange rate? Signaturegmail originated posts are filtered due to spam. <chop> I think you've gotten good advice about waiting for yourself to get efficient and not burdening yourself with technical diving gear until you have more experience. Relaxation is only part of the deal. Another big part is learning to adjust your trim and getting yourself streamlined so you can move efficiently as possible with the least drag and then learning to kick efficiently. Also, as you gain experience you will use much less gas for buoyancy control. And do something about that mask. Every time you clear it completely at depth you're probably blowing nearly a cubic foot of air you could be breathing instead. Technical gear is much heavier, may very well require a larger wing (or BC, though a backplate/wing is preferable for doubles), has far more drag, and is operationally more complex. Also, it's a lot harder to get back aboard a boat wearing doubles in a heavy swell, and mastering the timing needed to exit under those conditions is best done wearing something as light as possible. Consider instead using larger singles (100s or 125s) if they are available. Get the basics down first with a rig that's easy to get around in. Your overall margins for error are often greater wearing a single than wearing doubles. If you are using rental gear, and different gear every time, then this won't be the source of your high consumption rate, but if you have your own gear or always get the same BC or reg when you rent, have your buddy check them underwater for leaks (sometimes called a "bubble check") if your gas consumption is much over 1 cubic foot/minute at sea level. (That's 2 CFM at 33', 4 CFM at 99', etc.) For the "where'd my octo go?!" problem, consider breathing through the octo and putting the primary on a bungee or surgical cord necklace around your neck. It's really hard to lose track of the primary that way. To donate gas to another diver, hand the diver the reg in your mouth (the yellow-colored octo with the longer hose) put the primary on the cord around your neck in your mouth, clear it, and breathe. By all means discuss this with an instructor or a local experienced diver first and have someone show you how. (I have absolutely no clue why all the agencies teach clipping the octo off on the harness somewhere instead, which seems nonsensical to me, but then again I learned to dive before octos were commonly used so perhaps my view is skewed.) So far as swimming through a surge goes, just keep the same (efficient as possible) kick going. You will move through the water. The water will move back and forth, so you'll go faster over the bottom when it's moving your way and slower when it's not, but your *average* forward speed in a no-current surge will be the same as it is in still water. You'll use far less energy (=gas!) and be less stressed this way. Don't *ever* fight the water except as a desperation move--and then, understand going in that it may well not work. Ride with it instead, understand what it's doing, and plan to use it to your advantage. Do be aware that a strong surge can suck you into a wreck, and give openings a wide berth. If a surge is very strong, remember that if it's shallow enough you can drop to the bottom to grab something when it's going the way you don't want to go, and let go when it will carry you forward. Obviously, don't do this on coral or other delicate bottoms, but on sandy bottom, rock bottom, or on a wreck it's very efficient and easy. I have seen divers that don't know this simple trick blow through their air in a current if they fell off the line (on shallow non-deco dives) and surface down-current from the boat, drifting a mile or more before all divers were up and the captain could go find them. HTH, SignatureJohn Eells > <chop> > [quoted text clipped - 17 lines] > rig that's easy to get around in. Your overall margins for error are > often greater wearing a single than wearing doubles. I'm a big fan of "less is more", but given the "opportunity cost" of scuba, I'd like to get an other 10 minutes or so out of each dive, and esp. not be the guy that ruins it for everyone else by forcing an early retreat to the surface. Certainly I need to continue to improve my efficiency (air wise). What you and Greg say rings true with the Swiss guy I met there ... he said he was an air hog for a few years until he settled down. (He also depended on his wife's tank to extend his time, he confessed) My mask is "old" and the volume compared to today's masks is pretty big. Replacing that with a lower volume mask, esp. one that doesn't need as much clearing, should help somewhat too. > If you are using rental gear, and different gear every time, then this > won't be the source of your high consumption rate, but if you have your > own gear or always get the same BC or reg when you rent, have your buddy > check them underwater for leaks (sometimes called a "bubble check") if > your gas consumption is much over 1 cubic foot/minute at sea level. > (That's 2 CFM at 33', 4 CFM at 99', etc.) I wasn't crazy about the state of the O-rings on some bottles, and I could see a small stream of tiny bubbles from some divers. I could hear my own tank streaming a little on one occasion. I mentioned this to the instructor and it was de-nada time. On the deep dive, on the way there, the very experienced other diver actually had his own spare rings (of course) and he replaced it before going down. > For the "where'd my octo go?!" problem, consider breathing through the > octo and putting the primary on a bungee or surgical cord necklace > around your neck. It's really hard to lose track of the primary that > way. I think that option was also in the PADI manual or one of the videos. I like the idea of the "yellow" one being so visible to whoever needs it. I'm not a huge fan of the signaling for air. As far as I'm concerned, if you need to grab some of my air, you probably have a good and possibly urgent reason to do so. Come and get it and tell me about it after the fact. It was a freak thing. In the pool I did it several times, and in the open dives too. It was just that one time where who knows... > To donate gas to another diver, hand the diver the reg in your > mouth (the yellow-colored octo with the longer hose) put the primary on [quoted text clipped - 4 lines] > which seems nonsensical to me, but then again I learned to dive before > octos were commonly used so perhaps my view is skewed.) It seems natural to me that the spare (yellow) be clipped in front and easy for the "needer" to find once the giver has assented. The clip on my vest (I had the same one every day) was too loose, however, so my spare was in the side pocket. The instructor showed me how to double it back and push it into a pocket on the BCD, so it would be more visible and accessible. > So far as swimming through a surge goes, just keep the same (efficient > as possible) kick going. You will move through the water. The water will [quoted text clipped - 5 lines] > understand going in that it may well not work. Ride with it instead, > understand what it's doing, and plan to use it to your advantage. Got it. That's now three different versions I've heard! (One from a Swiss guy there (relax against, swiftly when with), Greg's version and yours. Do fins really make a difference? My fins 25+ years old, are stiff-ish plastic (mares). They're strapless. My SO bought a pair as part of a snorkeling kit before we went down. Nice mask, the fins were stiff and had vents, I assume to make the return stroke easier and the power stroke more efficient. (?). > Do be aware that a strong surge can suck you into a wreck, and give > openings a wide berth. Didn't know that one. Makes sense. > If a surge is very strong, remember that if it's shallow enough you can > drop to the bottom to grab something when it's going the way you don't [quoted text clipped - 5 lines] > down-current from the boat, drifting a mile or more before all divers > were up and the captain could go find them. Air sucking aside I'm a pretty strong and efficient swimmer (though obviously needing a "lower state" swim technique for scuba). On one of the coral areas, I did (sort of) get the hang of getting into the "shadow" of the current. But as were visiting a larger area, at some times the current had to be faced. I swim pretty close to the bottom, so that does help. Signaturegmail originated posts are filtered due to spam. >I just got my PADI OW, and added a night, wreck and deep (110') dives, >and others for a total of 12 dives. (San Andres, Columbia). [quoted text clipped - 17 lines] >regulars with a cross manifold? (whatever it's called). Can this be >'mix and match'? eg: dive with 1 or 2 bottles as needed? This sounds like a troll. Or, at the very least, someone that isn't going to be with us much longer. OOA on one dive and having to breath off of someone else? For 10 minutes? If you had panicked, you could have killed her, too. Newbie and doing deep, wreck, rocks, etc. With a 30-year old mask? I'm not buying this one. > This sounds like a troll. Or, at the very least, someone that isn't > going to be with us much longer. OOA on one dive and having to breath [quoted text clipped - 3 lines] > Newbie and doing deep, wreck, rocks, etc. With a 30-year old mask? > I'm not buying this one. Masks made in 1980 no good anymore? The guy said he got certified in Colombia, for god's sake, and by PADI, and it sounds like he followed standard advice to take AOW immediately after OW. Why would you disbelieve him? Plenty of "resort course" DMs take uncertified divers to 80' plus, at least anecdotally. >> This sounds like a troll. Or, at the very least, someone that isn't >> going to be with us much longer. OOA on one dive and having to breath [quoted text clipped - 3 lines] >> Newbie and doing deep, wreck, rocks, etc. With a 30-year old mask? >> I'm not buying this one. kjw: Sorry I can't reply directly. I filter gmail as there is too much spam. Happens to be the unadulterated truth. I bought the Mares mask in Destin, FL in the early 1980's for snorkeling. Here it (and I) am: http://photo.net/photodb/photo?photo_id=10587110 You should recognize the older style mask. I may have exaggerated the age of the mask a tad, but it is older (by at least 5 years) than my 19 yr. old son. So call it 24 years? IAC, it leaks more than I can stand so I will be buying a new one before the next trip. If you want a scan of my log book (all 12 dives) just say so. (My log book is the last page of my PADI manual..) Or for that matter a copy of the PADI application that I scanned before sending in the other day? Deep? 110' (not 130). But to P U off, there was a tunnel a little over a meter wide for about 30 meters. Swam that too (at about 110' rising to about 90'). I was nervous on that one as I motioned another diver ahead of me and he swam much slower than I wanted to... I did feel a little out of sorts on that one, I admit. The instructor would not have let me on that dive had I not demonstrated that, while a clumsy air hog newbie, don't panic and I can handle myself. (I could also recite a long litany of silly mistakes I made like beginning a decent while still breathing from the snorkel and putting on my BCD/tank in the water without assuring my hoses were clear - my SO sorted that out for me). As to the wreck, it would likely not qualify as a wreck dive. It was a small (100') cargo ship that had split open, so most of the ship was accessible without going into a confined area. The few confined areas there were, I did not go into at all. Here it is (with clumsy me holding a bagged lion fish the instructor caught - they are an invasive speicies there - he also tried to kill a much larger one that my SO found on an earlier dive). http://photo.net/photodb/photo?photo_id=10587153&size=lg you can see how clumsy I am in that one... As to panic and killing my SO, I don't think so. I simply swam right above her holding onto her tank strap with thumb and finger neither pushing nor dragging, just gently paddling to keep up. I had, in those instances, 600 psi, and on those shallow dives either of us could have surfaced with no problem w/o air and keeping weights on never mind with my 600psi and her at 1200 or so ... after the fact. On the written tests (2) I scored perfect. So did my SO. But that's because we both actually read the manual cover to cover (which I understand is not quite the norm given their insistence that we watch the insipid PADI videos that covered the same thing - less deeply). But I suppose you can't believe that either. Sorry for your disbelief, but that's entirely your problem, not mine. > Masks made in 1980 no good anymore? The guy said he got certified in > Colombia, for god's sake, and by PADI, and it sounds like he followed > standard advice to take AOW immediately after OW. Why would you > disbelieve him? Plenty of "resort course" DMs take uncertified divers > to 80' plus, at least anecdotally. I had done two "guest" dives with DM's (Cancun and San Andres) before deciding to do the PADI. But both of those were to no more than 30 ft. On the last dive of this trip, there was one guy who had done 6 "guest" dives on this trip, but never to more than 30 ft or so. I did not get the impression the instructor's or DM's would take him any deeper than that without the course. Signaturegmail originated posts are filtered due to spam. okay, okay, I stand corrected. Sorry for accusing you of trolling. It's pretty obvious to me now that you're not. No need to scan your logbook. I believe, I believe. That being said, I think that perhaps you're being a bit aggressive with your diving at your stage. Others have explained better, but I do think spending time a much shallower depths will serve you well and keep you underwater longer. > okay, okay, I stand corrected. Sorry for accusing you of trolling. > It's pretty obvious to me now that you're not. [quoted text clipped - 5 lines] > do think spending time a much shallower depths will serve you well and > keep you underwater longer. Good thing I came to check here on Google groups, or I would not have seen your gracious reply. So I apologize for my abrupt response. Aggressive? Sort of. I felt I was pushing it while I was there. Euphoric/adrenaline rush? But, other than one dive, which started badly for me and I was uncomfortable breathing until I actually got near the bottom (while considering returning to the boat), set my buoyancy and just relaxed for a couple minutes, I feel very much aware of everything around me and my own state. Maybe that's a sucker state I need to look out for... By the last dives (which were very easy) I was focusing more on using less energy, seeing more, really getting close to the coral and looking in nooks and crannies for things. It was more about "what's there in the dive" instead of jetting around the reef until air was up. Cheers, Alan [Default] Thus spake Alan Browne <alan.browne@FreelunchVideotron.ca>: >I just got my PADI OW, and added a night, wreck and deep (110') dives, >and others for a total of 12 dives. (San Andres, Columbia). > >My key issue is that I'm 6'2" and broad/deep chested and go through air >like crazy even when I do my level best to be slow and calm. You will. That's what experience is all about. Most of us here hate being buddied with a nube. But if I'm on a trip with more than three days of diving, I might (MIGHT) let you pay me $35 and I'll teach you some PADI specialty (I'm a PADI instructor, something almost everyone here has accepted as my failing). What I'll really teach you is how to breath. You won't be going 90 mintues, but you'll learn how to breath and that will eventually get you there. And I'll have paid for a day of diving. :-) > For my >deep dive, the instructor dragged down an extra bottle/regulator set. [quoted text clipped - 5 lines] >stealing her air). On another dive, there I was at 20 ft with 0 air >left, I could suck in a few last breaths as I slowly made my way up. We have (had?) a dude around here who's rather well muscled and had the same problem. He got through by diving until he mortgaged the house and bought a 68 Bug. >Now starting to look at buying gear (all I have are fins, mask and >snorkel, though my 30 year old mask needs replacing, leaks too much [quoted text clipped - 3 lines] >regulars with a cross manifold? (whatever it's called). Can this be >'mix and match'? eg: dive with 1 or 2 bottles as needed? Personally, I've got a lot of concern with a nube diving with multiples, but I'll defer to the guys who do it regularly. Signature- dillon I am not invalid I love my country, It's my government I fear. Hey, turnabout's fair play. : [Default] Thus spake Alan Browne <alan.browne@FreelunchVideotron.ca>: : [quoted text clipped - 37 lines] : Personally, I've got a lot of concern with a nube diving with : multiples, but I'll defer to the guys who do it regularly. To get your breathing rate down, get a mate to move to the tropics and buy a big boat. Scraping barnacles with only a hookah hose, a paint scraper and a light weight belt scraping barnacles for an hour or so to make you forget about breathing and become much more relaxed. Worked for me. SignatureBrad Leyden 6° 43.5816' S 146° 59.3097' E WGS84 To mail spam is really hot but please reply to thread so all may benefit (or laugh at my mistakes) > To get your breathing rate down, get a mate to move to the tropics and buy a > big boat. Scraping barnacles with only a hookah hose, a paint scraper and a > light weight belt scraping barnacles for an hour or so to make you forget > about breathing and become much more relaxed. Worked for me. I'll take that under advisement. Signaturegmail originated posts are filtered due to spam. On Jan 28, 5:03 pm, Alan Browne <alan.bro...@FreelunchVideotron.ca> wrote: > I just got my PADI OW, and added a night, wreck and deep (110') dives, > and others for a total of 12 dives. (San Andres, Columbia). [quoted text clipped - 17 lines] > regulars with a cross manifold? (whatever it's called). Can this be > 'mix and match'? eg: dive with 1 or 2 bottles as needed? I'm 6'1" 240lbs and it isn't muscle. I've been diving for about 2 1/2 years and the days of heavy air consumption are still in my memory. I used to go through air really fast and I think I know why. Anxiety and nervousness is the big one. This can build up while anticipating a difficult dive or when gearing up trying not to keep the others waiting. Up here in Ontario even shore dives can be intimidating for new divers (lots of rocky shorelines.) On dives where I was anxious I would try to relax before the dive. On the boat I would close my eyes and breath deeply and try to calm myself. When gearing up for a dive I'd take my time relax in-between donning gear and take a moment for a calming breath. If I found myself breathing even slightly heavily when I got in the water I would hang on the surface for a minute or two letting my arms and legs relax while calming my breath. If it was safe I would close my eyes to help. I would try to be the first one in so that I could spend more time relaxing. It is in your buddy's best interest to give you the time to relax, it extends their dive too. Under water I had several problems. Buoyancy was a big one. Many new divers fin continuously because they are negatively buoyant. This additional work adds to air consumption. When properly buoyant you should be able to remain completely still and sink when exhaled and rise when inhaled. Then all the work you have to do will be just to move you forward. Stop and check your buoyancy when you think it's off or when you've made a big depth change. Slow down everything, act like an astronaut. Don't speed everywhere, take your time. Trim is another important thing. If your trim is not right then you are not slipping through the water effectively and using more energy as a result. Streamline your body so that it's almost horizontal. You may have to get used to craning your neck a little. Keep your arms in close and don't have lots of stuff hanging off you, keep it stowed in pockets or tucked behind you. For small adjustments in depth, use breath control to rise or lower. If your buoyancy is correct you should be able to breathe deeply, hold for a few seconds and begin to rise. A quick exhale and equally deep inhale will keep you rising. To descend do the opposite, exhale completely and hold for a few seconds, if you need to descend further take a quick breathe and exhale quickly. You will waste less air in your BC There are other things you can do to use less air. Like use an existing breath to clear your mask. As you become more relaxed underwater you'll need less lead to sink. Less lead means less air in your BC and less bulk to push through the water. Do a weight check occasionally. Finally take some time to notice your muscles, are they tense or relaxed during a dive? Try to relax everything. I call it getting your balance underwater. When I started diving I felt like I would flip over if I didn't scull with my hands or adjust with my fins. On the surface it was similar, if I didn't do anything I felt like I would tilt forward. It may just take time to get comfortable with your balance. If you tilt forward at the surface try using less air in your BC. Another technique is leaning back more, like you're in a recliner. It took me dozens of dives to get this under control. Now, despite being big, most divers I dive with use more air than me and most are smaller. If you try everything and you can't reduce your air enough, pick up a larger tank. Some of the tropical dive operations have 100s for that purpose, ask for them while away. |
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