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Scuba Forum / Scuba Equipment / November 2005Back Inflation BCD
Just got back into diving this year (5 yr hiatus). I have a ScubaPro Classic BC (10 years old) but it rides high now and the cummerbund runs tight. My weight belt likes to fall below my waist (if you get my drift) at deep depth. My specialty instructor suggested a back inflation, weight integrated BC. I have seen several and read about many of them. I read some cause you to fall forward on the surface. Any suggestions on one that works for you? ChrisMSD > Just got back into diving this year (5 yr hiatus). I have a ScubaPro > Classic BC (10 years old) but it rides high now and the cummerbund runs [quoted text clipped - 3 lines] > some cause you to fall forward on the surface. Any suggestions on one > that works for you? From time to time I use the ScubaPro back inflation model - can't remember the name. Unless you are stuck to a BC, consider a back plate. They both work about the same. The weight integration is nice when you carry weights but it is a pain for lifting the BC out of the water or donning with pockets full. The possibility of the BC forcing your face in the water exists - especially if you can't turn over and float on your back. I've not experienced the problem but it has been discussed here. The BP/W is much more prone to pushing your head in the water when using certain types of tanks. The negative buoyancy and bulk of the kit makes it hard to maneuver and it's much easier to find it almost impossible to get your head out of the water without first submerging. > Unless you are stuck to a BC, consider a back plate. They both work about > the same. The weight integration is nice when you carry weights but it is > a pain for lifting the BC out of the water or donning with pockets full. The setup you chose will depend, in part, no how much weight you need. Personally, I like a stainless plate. It's 6 lb negative buoyancy turns out to be all I need to be virtually perfectly weighted in warm salt water, which is where almost all of my diving is done. It's too much weight in fresh water. The stainless plate also tends to simplfy trim adjustment. It moves weight from my waist and puts it closer to my center of buoyancy, my lungs. That, in turn, balances me in the water, reduces the effort required to maintain a horizontal position (to almost zero in my case) which, in turn, reduces my gas consumption on most dives. It all works together. > The possibility of the BC forcing your face in the water exists - > especially if you can't turn over and float on your back. I've not > experienced the problem but it has been discussed here. The fact that Ben hasn't experienced the problem is a pretty good indication that the problem is way, way overstated. The only people who seem to be worried about it are those that sell jacket style BCDs and those who are in denial about the advantages of a plate and wing setup. That's not to say that there aren't people who, for very good reasons of their own, prefer a jacket style BCD. It is to say that being forced onto your face is rarely a major one of those reasons. > The BP/W is much more prone to pushing your head in the water when using > certain types of tanks. The negative buoyancy and bulk of the kit makes > it hard to maneuver and it's much easier to find it almost impossible to > get your head out of the water without first submerging. I'm not sure where any of this came from, but I am sure I disagree. Any system is just that, a system. Tank, plate, BCD, weights, thermal protection, etc. are all part of the system and need to be coordinated in such a way that the system works. Moving from front to back, my body is buoyant, the plate on my back isn't, my wing is buoyant, the tank behind that isn't. The layering effect leaves me nearly balanced at the surface. In all honesty, the nearly part means there is a slight, very slight tendency to tip forward. If I were unconscious, my kit would not float my face out of the water. Neither would by Seaquest jacket style BCD. Wen conscious, it's not a problem with either. Lee > > The BP/W is much more prone to pushing your head in the water when using > > certain types of tanks. The negative buoyancy and bulk of the kit makes [quoted text clipped - 11 lines] > face out of the water. Neither would by Seaquest jacket style BCD. Wen > conscious, it's not a problem with either. I'm 5'9" tall, and weigh 330#. With a bouyant AL80 (500psi), I get a slight forward tip, easily countered with a light kick. With -any- steel tank, from 80 to 130, I can lean back, or float comfortably on my back, with little control effort. >> > The BP/W is much more prone to pushing your head in the water when using >> > certain types of tanks. The negative buoyancy and bulk of the kit makes [quoted text clipped - 16 lines] > With a bouyant AL80 (500psi), I get a slight forward tip, easily countered > with a light kick. I also need a kick once in a while to dive properly. Adam > >> > The BP/W is much more prone to pushing your head in the water when using > >> > certain types of tanks. The negative buoyancy and bulk of the kit makes [quoted text clipped - 18 lines] > > I also need a kick once in a while to dive properly. We were talking about being on the surface... I thought... > Adam > Just got back into diving this year (5 yr hiatus). I have a ScubaPro > Classic BC (10 years old) but it rides high now and the cummerbund runs [quoted text clipped - 5 lines] > > ChrisMSD Well, there two different things. Weight integrated and back inflation. I have one BC which is both (Zeagle Ranger) and it's very good. On the integrated weights you need to look at where the weights are actually kept on the BC. My first BC the wieghts were in front and did roll me face forward on the surface, the back inflate didn't help that. The Ranger has the weights on the sides so they're neutral on the surface. I also have a SeaQuest passport and it has integrated weight but is not a back inflate and I really like it too. Since it's so light and collapses down to such a small size I use it for travelling. I normally dive cold water (Monterey Ca) and I float naturally anyway an when you add the two piece 7mm wetsuit I have to use a bit of weight to get under. I can't wear a weight belt (just falls off due to no hips). I split my weight between the integrated BC and a DUI weight and trim system. The weight and trim system is a weight belt with shoulder straps so it doesn't slip off. Of course when I travel to warm water sites (like when I dive in the Florida Keys) I only use a 1mm in the summer and a 3mm in winter so I need very little weight than when I dive cold water so I don't need weight and trim system diving warm. My suggestion is to rent a couple of different types of BCs to see what you like. Most shops have integrated and/or back inflate in the lower level BCDs (most won't actually rent high end BCDs). If you want to wear a belt but have problems try the DUI system. However I find that the integrated feels better to me because while I "cruzing" underwater both the lift and the weight of the BCD are just on the BCD where when I use the belt I feel that the BCD is holding me up and belt is pulling me down (Just my feelings). BTW... Avoid the SeaQuest Fusion at all costs!! I dropped almost $700 on one and it's horrible! Dennis "ChrisMSD" <chrismsd@cox.net> pounded away at his keyboard resulting in: :Just got back into diving this year (5 yr hiatus). I have a ScubaPro :Classic BC (10 years old) but it rides high now and the cummerbund runs [quoted text clipped - 3 lines] :some cause you to fall forward on the surface. Any suggestions on one that :works for you? My wife and I both use back inflation BCs and do not experience the fall forward problem. The brand name is Riptide, which may or may not still be around. The BCs are very similar to those made by the usual suspect (Oceanic, Dacor, USD, etc) One feature that our BCs have, as do many others, is small weight pouches at the back. They have a capacity for 1 kg each. This may or may not be significant in the lack of fall forward problem, but it is always a good idea to spread your lead around. Dan Bracuk If we don't succeed, we run the risk of failure. > Just got back into diving this year (5 yr hiatus). I have a ScubaPro Classic BC > (10 years old) but it rides high now and the cummerbund runs tight. My weight belt [quoted text clipped - 4 lines] > > ChrisMSD I use the Zeagle Escape, which is a light-weight version of the Ranger, and it works well. It has trim weight pockets in the back. Overall when on surface it does not force your head down. It's all a question of trim balance. Adam Much of it is about trim and balance. A BCD should not be confused with a life jacket (or PFD). A BCD is exactly what it says- buoyancy compensator- used while diving. You should easily be able to dive in a horizontal position. What the BCD does is more important during diving than it is on the surface. Part of your struggle on the surface could even be due to overinflation. While weight-integrated BCs eliminate the need for a weight belt, they often concentrate the weight on the diver. Some BDs, like the Zeagle Scout, integrate the weights along the tank... better. Other set-ups such as backplate/harness/bladder (BC/wing), especially a stainless steel backplate, distribute the weight more evenly along the diver's body. A ss backplate is 6lbs plus 3 lbs for a single tank adaptor- that's 9 lbs of usable ballast. Why not *use* your ballast rather than carry a bunch of lead just to sink? The weight is also streamlined with the body rather than creating more bulk across the hips and belly. More drag equals more effort. In addition, a backplate/harness configuration allows one to properly diaphragmatically breath, rather than restricting the breathing like a cumberbun across the abdominal area. Personally I have dove with many different gear configurations and tanks. By far the most comfortable is a backplate/harness. I am 5'5" and 130 lbs. I have used the same configuration as a 6'5" man 300 lbs (adjusted for me of course). My gear is also such that I can use it for any type of diving~ open water, ocean, single tank, double tanks, wet suit, dry suit, you name it. That's the beauty of it. It's minimalist and getting back to the basics. When shopping, see someone who specializes in Halcyon or Dive Rite or OMS- someone who makes a backplate. Most retailers want to sell bells and whistles- that's ok, because we all have to make a living. Do the homework- buy the very, very best and buy it once. >Just got back into diving this year (5 yr hiatus). I have a ScubaPro >Classic BC (10 years old) but it rides high now and the cummerbund runs [quoted text clipped - 5 lines] > >ChrisMSD  SignatureDive Cozumel / Yellow Rose US/Canada Toll Free: 866.319.2649 A.R. Salas #85- Downtown Cozumel > Much of it is about trim and balance. True, trim does come into play. But you can't beat the laws of physics, and for a vertical orientation on the surface, a Back Inflation BC *always* puts your lift source behind you, which can create an overturning moment ("face down" if you're not also trimmed out properly for a vertical orientation post-dive as well as your horizontal orientation during-dive trim. > A BCD should not be confused with a life jacket (or PFD). A BCD > is exactly what it says- buoyancy compensator- used while diving. True so far. > You should easily be able to dive in a horizontal position. See 'trim', above. > What the BCD does is more important during diving than it is on > the surface. Absolutely and unequivocally wrong. This constitutes dangerous advice, because: == the dive isn't over until the diver is out of the water == This means that the performance of the system when the diver is on the surface is a consideration that absolutely cannot be ignored. > Part of your struggle on the surface could even be due to > overinflation. Or it could be - as others have already stated - due to a buoyant AL80 tank making the immutable laws of physics rear its ugly head. Optionally, you can add to that a negatively buoyant UW camera that the diver holds in front of him which will also create a "face down" torque (Torque = Force * Moment Arm). > While weight-integrated BCs eliminate the need for a weight belt, they often > concentrate the weight on the diver. Some BDs, like the Zeagle Scout, > integrate the weights along the tank... better. True, the weight pockets on some Weight-Integrated BC's are poorly located. However, nothing stops you from simply wearing an old fashioned weight belt and positioning weights in the small of your back. > Other set-ups...A ss backplate is > 6lbs plus 3 lbs for a single tank adaptor- that's 9 lbs of usable ballast. And its also +9lbs in your airline baggage if you're a traveling diver. Have you seen how much some airlines now charge if you're even 1lb over? > Why not *use* your ballast rather than carry a bunch of lead just to sink? A good point, when it can be applied. > The weight is also streamlined with the body rather than creating more bulk > across the hips and belly. More drag equals more effort. Generally irrelevant on drift dives. > In addition, a backplate/harness configuration allows one to properly > diaphragmatically breath, rather than restricting the breathing like a > cumberbun across the abdominal area. That's a new one on me. Got quantitative data to prove your claim? > Personally I have dove with many different gear configurations and tanks. Same here. > By far the most comfortable is a backplate/harness. Learned on one a couple of decades ago. Today, the modern BP/W design of DIR vintage unfortunately lacks quick disconnects on the shoulders, which can make doffing the gear to reboard small chase boats quite inconvenient. A debate then follows about how "unreliable" QD snaps are. I've broken masks by having tanks fall on them more often than I've had any QD break. > When shopping, see someone who specializes in Halcyon or Dive Rite or OMS- > someone who makes a backplate. Oxycheq. > Do the homework- buy the very, very best and buy it once. But only after: a) you've been doing it long enough to prove that you're in it for the long haul and not part of the 70% that drops out within 5 years... and b) that you've gotten enough experience to know what it is that you really need (vs want) and can use that differentiation... and c) you know all of its trade-offs versus the alternatives and can thus make a good, informed decision. Unless all of these have been satisfied, you're wasting your money by "buying the best". Note that this is not unique to just dive gear. -hh >> Much of it is about trim and balance. > [quoted text clipped - 4 lines] > for a vertical orientation post-dive as well as your horizontal > orientation during-dive trim. That problem is solved by putting some trim weight behind the wing, either with tank band weights, trim pocket (as in the Zeagle Escape) or keel weight of Halcyon. Adam > >> Much of it is about trim and balance. > > [quoted text clipped - 6 lines] > > That problem is solved... Very few problems are really "solved". All you do is find a more acceptable alternative within your available trade-offs. > ... by putting some trim weight behind the wing > either with tank band weights, trim pocket (as in the Zeagle Escape) > or keel weight of Halcyon. Yes, these all help to relocate ballast to the rear, although the keel weight isn't a good option for travel diving. In my personal case, I've already moved all of my warmwater lead (~8lbs) to behind my back, distributed between 4lbs in trim pockets (their max rating) and a 4lb weight on a weightbelt in the small of my back (puts it significantly further back than the WI pockets). I've picked up a tank band weight pocket, but haven't installed it yet, as my last dive location didn't have currents or the chase boats that can get lost where long surface floats are more likely to happen, so it wasn't a priority yet. FYI, the reason this seems so extreme of a ballast shift is because of my negatively buoyant UW camera carried in front of me. This does also mean that YA option I've considered is to stop carrying my UW camera, but I'll go back to a Jacket Style before doing that. -hh > True, trim does come into play. But you can't beat the laws of physics, > and for a vertical orientation on the surface, a Back Inflation BC > *always* puts your lift source behind you . . . It always puts some lift behind you. For most of us, our bodies and any thermal protection we have on provide lift to the front. Since the body displaces more water than the BCD, a greater percentage of the total lift comes from that source. > Yes, these all help to relocate ballast to the rear, although the keel > weight isn't a good option for travel diving. In my personal case, I've > already moved all of my warmwater lead (~8lbs) to behind my back, > distributed between 4lbs in trim pockets (their max rating) and a 4lb > weight on a weightbelt in the small of my back (puts it significantly > further back than the WI pockets). You wear 16 lbs of lead in warm water? > FYI, the reason this seems so extreme of a ballast shift is because of my > negatively buoyant UW camera carried in front of me. Negatively buoyant cameras are a poor idea. Whenever possible, camera equipment should be neutral to slightly buoyant (giving you a chance to recover it if it gets away from you). Add some buoyancy to the camera and the rest of your kit will be a lot easier to trim out. > This does also mean that YA option I've considered is to stop carrying > my UW camera, but I'll go back to a Jacket Style before doing that. I stopped carrying mine, but for a much different reason. I dive because I enjoy it. As much as I like having images to share with others, I found that I was spending more time getting good pictures than I was spending enjoying myself. Further, when I take a camera, my buddy doesn't enjoy the dive as much either. I chose to leave the camera behind. Lee > > ...In my personal case, I've > > already moved all of my warmwater lead (~8lbs) to behind my back, [quoted text clipped - 3 lines] > > You wear 16 lbs of lead in warm water? No, I wear a total of around 8lbs when wearing a full 3mm wetsuit (default). Its distributed as 4lbs on a weightbelt (located in the small of of my back), plus a total of 4lbs which is evenly distributed as two 2lb'ers into the BC's rear pockets. These rear pockets are only rated for 2lbs max each, so I can't add any more weight in them. FWIW, this configuration retains having ~50% of my weights as immediately ditchable. > > FYI, the reason this seems so extreme of a ballast shift is because of my > > negatively buoyant UW camera carried in front of me. [quoted text clipped - 3 lines] > recover it if it gets away from you). Add some buoyancy to the camera and > the rest of your kit will be a lot easier to trim out. Either positive or negative will be a trade-off someplace. I have found that a negatively buoyant camera is preferred at times, because I'm then free to put it down on the bottom to "do other stuff". For example, I've used it as a portable UW landmark, as well as having left it under the boat when its been a good dive and I ran out of film long before I ran low on air. Similarly, one of my strobe arm assemblies works off of a wireless slave sensor, and since its negative, I can take it completely off the camera and then preposition the strobe in/on/under a coralhead to fire at the subject as a "very" remote flash self-reliantly, instead of having to have a buddy/assistant present present to hold it for me. -hh > Either positive or negative will be a trade-off someplace. True, which is why neutral, if possible, is preferred. > I have found that a negatively buoyant camera is preferred at times, > because [quoted text clipped - 7 lines] > self-reliantly, instead of having to have a buddy/assistant present > present to hold it for me. You must make more than me, or at least more than I did back when I bought my Nikonos, etc. I didn't put anything down anywhere, ever. It was either attached to my wrist or clipped off to a D ring. Lee > > I have found that a negatively buoyant camera is preferred at times, > > because I'm then free to put it down on the bottom to "do other stuff". > > You must make more than me, or at least more than I did back when I bought > my Nikonos, etc. I didn't put anything down anywhere, ever. It was either > attached to my wrist or clipped off to a D ring. Its a product of the dive environment...and equipment. For example, I'd not trying to suggest purposefully dropping one's UW camera while on a live boat drift dive. Similarly, my UW camera is sufficiently negatively buoyant such that its not going to drift or tumble away from where I'd put it down in even a moderate current. My comment included what I've done over a couple hundred dives on Cayman Brac & Little Cayman. For me specifically in this location, I consider my general risk of unintended loss to be acceptably low, since: (a) I have generally good familarity with most of the dive sites, (b) the UW visibility is generally very good, (c) the generally no meaningful current won't cause the camera to move, or (d) to prevent me from swimming back to a particular location during a dive. Naturally, my remaining air and bottom time is part of the decision-making process too. -hh >> Other set-ups...A ss backplate is >> 6lbs plus 3 lbs for a single tank adaptor- that's 9 lbs of usable ballast. > > And its also +9lbs in your airline baggage if you're a traveling diver. > Have you seen how much some airlines now charge if you're even 1lb > over? Ali Plate and lightweight SS tank adaptor (3lb total). I then use a spare tank strap to add ~half my remaining weight to the cylinder. For warm water this can mean zero weight belt. For cold water diving, this means a minimal weight belt with weights set just outside the edges of my plate (for comfort). Of course, with twin 12l steels, I don't need too much extra behind, but for a single, it's a low hassle way to go. I'm also investigating a V weight for my plate, but I want to mould it in a SS plate rather than my main Ali for heat issues. Dan. > >> Other set-ups...A ss backplate is > >> 6lbs plus 3 lbs for a single tank adaptor- that's 9 lbs of usable ballast. [quoted text clipped - 4 lines] > > Ali Plate and lightweight SS tank adaptor (3lb total). Yes, this solves the "travel weight" problem, but then you don't really have the rear mass present to address the "surface float" trim balance. Besides, I personally am of the opinion that single tank adaptors are an ugly klunge that adds unnecessary complexity and failure points to a rig. I'd rather go Mike's route and move the tank close to the back. > I then use a spare tank strap to add ~half my remaining weight > to the cylinder. For warm water this can mean zero weight belt. Which restores the trim balance, but then means no ditchable weight in case of emergencies. > Of course, with twin 12l steels, I don't need too much extra behind, > but for a single, it's a low hassle way to go. My challenge is in the other direction...floaty AL80, but carrying an UW camera (Nikonos w/dual strobes), which is 2-3lbs negative and which gets carried in front of me, which is a moment arm around 1-1.5ft long. To mathmatically balance off my camera's torque, it needs ~6lbs of weights positioned roughly 6" behind the bladder - ie on the back of the tank, which means that a heavy BP won't do it...its resolution is by adding a good weight pocket onto my tank strap. Either that, or get rid of my back inflation rig and go back to a Jacket Style like I had previously used for probably ~20 years of diving, for a Jacket will move the buoyancy centroid forward relative to the vertically oriented diver. -hh > Besides, I personally am of the opinion that single tank adaptors are an > ugly klunge that adds unnecessary complexity and failure points to a > rig. I'd rather go Mike's route and move the tank close to the back. It's a trade off. The STA provides a bit of relief between the tank valve/first stage and the back of my head. This, in turn, allows the tank to be placed a bit higher, affecting trim and ease of reaching the valve as necessary. > Which restores the trim balance, but then means no ditchable weight in > case of emergencies. If you are properly weighted and have no compressible spaces, a wetsuit, for example, you don't need much, if any ditchable weight. I dive quite comfortably with none. > My challenge is in the other direction...floaty AL80, but carrying an UW > camera (Nikonos w/dual strobes), which is 2-3lbs negative and which gets > carried in front of me, which is a moment arm around 1-1.5ft long. Get rid of the floaty Al80. Try a neutral 80 or slightly negative steel hp100. > To mathmatically balance off my camera's torque, it needs ~6lbs of > weights positioned roughly 6" behind the bladder - ie on the back of the > tank, which means that a heavy BP won't do it...its resolution is by > adding a good weight pocket onto my tank strap. Add buoyancy to the camera rather than weight to the tank. > Either that, or get rid of my back inflation rig and go back to a Jacket > Style like I had previously used for probably ~20 years of diving, for a > Jacket will move the buoyancy centroid forward relative to the > vertically oriented diver. Not until it's completely filled. Lee > Get rid of the floaty Al80. Try a neutral 80 or slightly negative steel > hp100. I'll buy 400 tanks to convert Cayman Brac over if you can get Bob to buy the 40,000 tanks to convert Cozumel over. Deal? :-) But seriously, the issue of dealing with "floaty" AL80's in resort diving is generally an unavoidable one virtually worldwide. AL80's are simply too well suited to the rental/resort marketplace to not be their generally preferred product selection: they're dirt cheap and they don't rust like ferrous tanks. In fact, in some modestly remote destinations, I've seen that the expense of getting an AL80 re-hydro'ed after 5 years wasn't financially prohibitive: in these cases, it was less expensive for the dive operation to ditch the old tanks and just buy more new AL80's. -hh "-hh" <recscuba_google@huntzinger.com> pounded away at his keyboard resulting in: :But seriously, the issue of dealing with "floaty" AL80's in resort :diving is generally an unavoidable one virtually worldwide. I love those floaty AL80s. Negatively buoyant tanks just add weight to your back, making you work harder, and tend you flop you about if you turn sideways. Vive la positive buoyancy. Dan Bracuk If we don't succeed, we run the risk of failure. > I love those floaty AL80s. Negatively buoyant tanks just add weight > to your back, making you work harder, and tend you flop you about if > you turn sideways. Different strokes, and all that. If everything works together, all kinds of configurations can work well. Lee > "-hh" <recscuba_google@huntzinger.com> pounded away at his keyboard > resulting in: [quoted text clipped - 4 lines] > to your back, making you work harder, and tend you flop you about if > you turn sideways. Hmm, I have a 24kg 15 ltr steel tank and a drysuit with a shoulder vent. Can't say I'd ever noticed this problem. Signature"If a man empties his purse into his head, no man can take it away from him. An investment in knowledge always pays the best interest." - Benjamin Franklin >> Get rid of the floaty Al80. Try a neutral 80 or slightly negative steel >> hp100. > > I'll buy 400 tanks to convert Cayman Brac over if you can get Bob to > buy the 40,000 tanks to convert Cozumel over. Deal? :-) Good point, but be careful. Bob made more money in one (pick your time period) on (pick your .com stock) than any other (pick your descritive term). I'm sure he could afford to buy all the tanks for Cozumel. On the other hand, he might just suggest using Aldora, assuming they still use hp steel tanks. > But seriously, the issue of dealing with "floaty" AL80's in resort > diving is generally an unavoidable one virtually worldwide. That does seem to be the case. It's also one of the reasons I own several Halcyon trim weight pockets. Lee >>>> Other set-ups...A ss backplate is >>>> 6lbs plus 3 lbs for a single tank adaptor- that's 9 lbs of usable ballast. [quoted text clipped - 35 lines] > > -hh I said *can* have zero weight belt. In warm water I prefer to have about 2lb to 4lb max on a belt - plenty of ditchable weight to make me just positive (but a low enought amount that I can remain submerged with a little effort if I lose the belt - for stops) It's also useful for trim. My STA is more because of my plate than because I want it. If I wanted a STA less setup, I would but a specifically STA less plate design. However there are very few good ones, and none are particularly good with twins as well. I do not consider a plate with strap slots alone to be a good non-STA plate as it will have less stability for the cylinder - The plates with extra bends to produce a reverse channel in the back are the only ones that I would use without a STA. (Portland Oceaneering's Mark II and some of the designs from UKRS regulars come to mind) You could also counter you camera issue by adding a float to your camera - make it 1lb negat've instead of 2-3. This should still be enough for stability, and would make life a lot easier. Dan. >>> Ali Plate and lightweight SS tank adaptor (3lb total). >> Yes, this solves the "travel weight" problem, but then you don't really >> have the rear mass present to address the "surface float" trim balance. A good reason to buy a few trim pockets and locate them where ever you need to to get whatever trim you find most desirable. >>The weight is also streamlined with the body rather than creating more bulk >>across the hips and belly. More drag equals more effort. > > Generally irrelevant on drift dives. I'd have to disagree with that. I've swum against the current on a drift dives many times, to watch something, to wait for a buddy, to avoid an object, and I've seen others do the same. >>In addition, a backplate/harness configuration allows one to properly >>diaphragmatically breath, rather than restricting the breathing like a >>cumberbun across the abdominal area. > > That's a new one on me. Got quantitative data to prove your claim? I doubt anyone has measured it, but it is very noticeable. The last time I wore a wrap-around BC was during certification. 7mm suit that was already too tight, lots of weight as per the instructor. I pumped up the BC to discover I could either float or breathe, but not both. >>Personally I have dove with many different gear configurations and tanks. > [quoted text clipped - 8 lines] > are. I've broken masks by having tanks fall on them more often than > I've had any QD break. Just pull it over your head. Quick and easy if you're in the water. >>>In addition, a backplate/harness configuration allows one to properly >>>diaphragmatically breath, rather than restricting the breathing like a [quoted text clipped - 6 lines] > already too tight, lots of weight as per the instructor. I pumped up the > BC to discover I could either float or breathe, but not both. The wrap-around BC you refer to is designed to stabilize the diver by providing lift around the body - as opposed to one side of the body, like the back for example. With this type of BC cinched, adding air can produce the squeeze you experienced. Various designs exist for BC's including back inflation models similar to the BP/W and many of these BC's feature a cummerbund. The cummerbund facilitates donning by holding the BC in place while the waist strap is buckled and / or adjusted. A cummerbund shouldn't restrict breathing. > The wrap-around BC you refer to is designed to stabilize the diver by > providing lift around the body - as opposed to one side of the body, like > the back for example. Few, if any BCDs provide lift around the body. Most provide it mostly in the back and, when fully inflated, to the sides. While the tendency toward tipping forward may be slightly less, it's still there. In either case, it's not signficant. > With this type of BC cinched, adding air can produce the squeeze you > experienced. Most, but not all, are designed to inflate away from the body. On them, the only way I know of to get squeeze of this type is by improper adjustment to the clip, or other attechment, that keeps the front of the jacket together. >A cummerbund shouldn't restrict breathing. Actually, they probably all do to some extent. On most jacket style BCDs, the bummerbund (cumberbund?) has to be snug to keep the BCD and attached tank stable. Even an elastic one will restrict breathing somewhat. Most don't find it to be a problem. The too tight wetsuit described is much more likely to be a source of significant breathing difficulty. Lee >> The wrap-around BC you refer to is designed to stabilize the diver by >> providing lift around the body - as opposed to one side of the body, like [quoted text clipped - 12 lines] > adjustment to the clip, or other attechment, that keeps the front of the > jacket together. http://www.scubapro.com/products/bcs/miscella/bc_types.asp I've used the stabilizing jacket and back flotation jacket. The back flotation when inflated will push you forward in the water but not normally cause squeeze. The stabilizing jacket on the other hand will almost always cause squeeze. The force holding the diver upright is exerted outward by the jacket circling the diver's body while the opposing force is inward squeezing the body. It is commonly felt at the surface and is most annoying. >>A cummerbund shouldn't restrict breathing. > > Actually, they probably all do to some extent. On most jacket style BCDs, > the bummerbund (cumberbund?) has to be snug to keep the BCD and attached > tank stable. Even an elastic one will restrict breathing somewhat. Most > don't find it to be a problem. I would think an elastic band could restrict breathing because it is capable of contracting after immersion. Straps on dive gear tend to become loose after immersion when diving wet. When diving dry the drysuit provides a cushion of air between the body and straps. In either situation they shouldn't restrict normal breathing. I took the spelling for cummerbund off the DiveRite website. That's the way ScubaPro spells it too. > The too tight wetsuit described is much more likely to be a source of > significant breathing difficulty. Absolutely. Given the divers equipment description and level of knowledge at the time it is highly likely the wetsuit contributed to breathing difficulty. > I've used the stabilizing jacket and back flotation jacket. Me too. > The back flotation when inflated will push you forward in the water but > not normally cause squeeze. The stabilizing jacket on the other hand will > almost always cause squeeze. Others, with the same experience, conclude differently. Look beyond the equipment for the problem. > I took the spelling for cummerbund off the DiveRite website. That's the > way ScubaPro spells it too. I'm not known for my spelling skills. How is it spelled when you wear it with a tux? Lee > I'm not known for my spelling skills. How is it spelled when you wear it > with a tux? Me either. I'd guess the same way. >> I've used the stabilizing jacket and back flotation jacket. And if someone is so paranoid about ending up face down in the water, they should go for an ABLJ (Adjusable Buoyancy Life Jacket) Horse collar (or toilet seat) style BC. I have a couple around and they are very simple, and not particularly uncomfortable. Most useable is a Buddy Pacific, but for fun, I very occasionally dive with an orange rubber Fenzy (mostly for the looks of disbelief ;->) They do guarantee face up position, and are still in production by a few companies. Dan. "ben bradlee" <up2u2figr@NoWay.Fool> pounded away at his keyboard resulting in: :The wrap-around BC you refer to is designed to stabilize the diver by :providing lift around the body - as opposed to one side of the body, like :the back for example. But what actually happens is that all the air goes to the highest point of the BC, so not much stabilization actually occurs. Dan Bracuk If we don't succeed, we run the risk of failure. > >>The weight is also streamlined with the body rather than creating more > >>bulk across the hips and belly. More drag equals more effort. [quoted text clipped - 4 lines] > drift dives many times, to watch something, to wait for a buddy, to > avoid an object, and I've seen others do the same. I've done likewise. But I did say "generally", which suggests that we don't spend our entire flipping dive swimming against currents. > >>In addition, a backplate/harness configuration allows one to properly > >>diaphragmatically breath, rather than restricting the breathing like a [quoted text clipped - 6 lines] > was already too tight, lots of weight as per the instructor. I pumped > up the BC to discover I could either float or breathe, but not both. Okay, now I see what you're talking about. Your problem here was improperly fitting gear. First, your heavy Farmer John wetsuit was too small which constricted the chest. Second, you probably did a classic novice error which was a "too tight" BC, but it wasn't the cummerbund on the inside, but the chest strap located above it "on the outside". As you inflated the BC, this chest strap prevented your BC from expanding outward, so the only direction it had to go was in. This simple equipment error is a training shortcoming, not an equipment shortcoming. > >>By far the most comfortable is a backplate/harness. > > [quoted text clipped - 6 lines] > > Just pull it over your head. Quick and easy if you're in the water. Been there, tried that. The problem is that this is overly simplistic, for getting out of your gear is not the only part of the diver exit process that you need to be concerned about: you need to be aware of the risks inherent within the entire process. The basic risk being introduced with the "pull over head" is that it generally requires you to have both hands free and usually requires you to briefly dunk your head. Both hands free means that you're probably losing contact with the chase boat and/or its tag line at least momentarily. A head dunk means that you're probably losing sight of the chase boat, which Mr. Murphy will use as an opportunity to try to move the boat to bonk you (head injury risk). Since you will first want to hand up your weights (and camera), to then minimize the risk of getting your head bashed, you'll have to release and back off, which then will require a second approaches by the chase boat instead of one, which is a risk of injury from the boat prop, etc. ..and it takes significantly longer too. There's few things more fun than floating in rough water waiting for your turn to board and watching a buddy team struggle for literally 10 minutes to get onboard the boat because they didn't really think through their gear configuration for the expected conditions (rough & windy). What this all boils down to is that the lack of an alternative to ditch your gear means that your dive exit plan includes by necessity a period in which you will have to lose sight of and lose contact with the chase boat. So while you can dive with 'loose' shoulder loops and slip off this way, but it is still not going to be As Quick, or As Easy as popping a QD, and it carries other trade-offs. There is no such thing as a free lunch. -hh There is one more very simple solution to the diver pick-up situation. Dive a boat with a ladder designed to be climbed while fully geared up. We do this all the time in the Northeast. When a diver is on the ladder his buddy or other divers wait his turn to board by hanging on to the tag line. Once on board you sit on the setup table and break down your gear. This is simplified even more when diving with great people. The boats crew as well as your fellow divers lend a hand in getting you stripped down and off the table. The table should be large enough to accommodate several divers at once. >> >>The weight is also streamlined with the body rather than creating more >> >>bulk across the hips and belly. More drag equals more effort. [quoted text clipped - 75 lines] > > -hh > There is one more very simple solution to the diver pick-up situation. Dive > a boat with a ladder designed to be climbed while fully geared up. We do > this all the time in the Northeast. I used to dive on the Sea Inn out of Belmar, NJ, so I'm familar with this ladder design. Large immersed ladders are most suited for when you're working off of a large boat on anchor/mooring. However, we don't always dive from large, "non-live" boats. In areas of the world where the SOP is to dive from small chase boats instead of directly from the liveaboard mother ship, the 'big ladder' generally isn't in the cards, nor is climbing out with all of your gear on. Particularly if its an inflatable, your "ladder" can be as minimal as a loop on the rope you're holding on with to stick a foot into. You can *try* to haul yourself out with all your gear on (if you're strong enough), but odds are that you'll doff the rig just like everyone else - - if for no other reason than to minimize heavy exertion while your Nitrogen gas load is at its peak. -hh > Learned on one a couple of decades ago. Today, the modern BP/W design > of DIR vintage unfortunately lacks quick disconnects on the shoulders, > which can make doffing the gear to reboard small chase boats quite > inconvenient. There's nothing "modern" about the DIR plate and wing design. It's a return to technology older than some of the divers here. > A debate then follows about how "unreliable" QD snaps > are. I've broken masks by having tanks fall on them more often than > I've had any QD break. So don't get into the debate. You want a quick disconnect, add one. It's your gear and your choice. Do, however, consider how that will effect other elements of your system. Even small changes can make major differences in other elements. Here are some examples: 1. If you use a long hose, you can't use a snorkel on the mask. The issue of carrying a snorkel almost never came up until people started using long hoses. 2. DIR-like harness system I use provides no way to constrain the relatively long inflator hose required to use a combination inflator/alternate. 3. My choice to put my computer, compass and spg in a console clipped off like a DIR-like spg, makes it inconvenient to put a stage bottle on my left side. Until I ditched the long hose, it was even less convenient to put it on the right. > Just pull it over your head. Quick and easy if you're in the water. I don't normally pull myine over my head. I slip out of it normally, much like you do a button up shirt. My shoulder straps are not so tight that I can't get out of my harness easily enough, in or out of the water. You left something off your list. In fact, if I ever add a quick release to my harness, it will be specifically to provide an easy and relatively painless way to remove my kit should I be injured. Any injury that makes movement painful or dangerous, which many do, would be less painful or dangerous if my kit can be removed, in the water or on the boat, by opening one or more shoulder quick disconnects. Lee >>Any injury that makes movement painful or dangerous, which many do, would >>be less painful or dangerous if my kit can be removed, in the water or on >>the boat, by opening one or more shoulder quick disconnects. I would like to say CUT THE STRAPS before you incur greater pain or injury if the event would ever arise. >>>Any injury that makes movement painful or dangerous, which many do, would >>>be less painful or dangerous if my kit can be removed, in the water or on >>>the boat, by opening one or more shoulder quick disconnects. > I would like to say CUT THE STRAPS before you incur greater pain or injury > if the event would ever arise. That will work too, provided the right tool for cutting them is available. I don't think I'd much like somebody sawing at my straps while I lay there with a broken arm much more than I'd like somebody trying to lift my arms out of a strap that has no release. I think either would be more than a little painful. On top of that, I'd rather not have my equipment damaged unless really necessary. Lee >>>Any injury that makes movement painful or dangerous, which many do, would >>>be less painful or dangerous if my kit can be removed, in the water or on >>>the boat, by opening one or more shoulder quick disconnects. > > I would like to say CUT THE STRAPS before you incur greater pain or injury > if the event would ever arise. Cut the straps?? Take the arm first! BTW... I have a left shoulder quick release for getting out in a hurry (like having to go to the "head" after an hour long dive in a dry suit). > > Learned on one a couple of decades ago. Today, the modern BP/W design > > of DIR vintage unfortunately lacks quick disconnects on the shoulders, [quoted text clipped - 3 lines] > There's nothing "modern" about the DIR plate and wing design. It's a return > to technology older than some of the divers here. Agreed. What has changed is that it no longer has the thin flexible straps that included a double D-ring slip fitting on each shoulder, as well as at the waist. The reason I said "modern" is because it was the more recent re-adoption and subsequent "improvement" of the basic BP/W design by the WKPP/DIR folk, which simplistically was thicker straps and the omission of the QD's. Since they dived in a full overhead environment, it did them no good to have quick-to-ditch gear, since if the rest of their OOA procedures fail, they're going to drown at the airless cave ceiling regardless of if they have their gear on or off. DIR's trade-off did recognize that the QD is of no particular benefit for gear ditching in a cave, but where they fell short was in recognizing that when the diver leaves an overhead environment, this conclusion is no longer true. > > A debate then follows about how "unreliable" QD snaps > > are. I've broken masks by having tanks fall on them more often than > > I've had any QD break. > > So don't get into the debate. You want a quick disconnect, add one. Already done. > Do, however, consider how that will effect other elements of your system. But of course. That was my intent in mentioning it...to tease out the necessity of really thinking through one's entire dive plan and all of its moving parts, across the entire process. Its what 'holistic approach' really means in actual practice. > Even small changes can make major differences in > other elements. Here are some examples: [quoted text clipped - 7 lines] > side. Until I ditched the long hose, it was even less convenient to put it > on the right. A good list of examples of trade-offs that should be holistically considered. -hh > DIR's trade-off did recognize that the QD is of no particular benefit > for gear ditching in a cave, but where they fell short was in > recognizing that when the diver leaves an overhead environment, this > conclusion is no longer true. Trade off? A gear configuration that's not optimal in all environments? Damn, I'm glad you live a lot way from me. In my mind, I can see the clouds forming above you. Expect the bolt of lightening soon. Such sacriledge. 8^) >> > A debate then follows about how "unreliable" QD snaps >> > are. I've broken masks by having tanks fall on them more often than [quoted text clipped - 3 lines] > > Already done. Yeah, I know. That was the generic "you." >> Do, however, consider how that will effect other elements of your system. > > But of course. That was my intent in mentioning it...to tease out the > necessity of really thinking through one's entire dive plan and all of > its moving parts, across the entire process. Its what 'holistic > approach' really means in actual practice. Damn, you're living on the edge. Lee >>DIR's trade-off did recognize that the QD is of no particular benefit >>for gear ditching in a cave, but where they fell short was in [quoted text clipped - 5 lines] > forming above you. Expect the bolt of lightening soon. Such sacriledge. > 8^) A little test I learned for use with companies selling computer technology was to ask when it was inappropriate to use their product. If they claim it is always the ideal solution the correct response is to laugh at them and ask to speak to someone who doesn't work in marketing. Could this be equally applicable to DIR? Signature"If a man empties his purse into his head, no man can take it away from him. An investment in knowledge always pays the best interest." - Benjamin Franklin > Could this be equally applicable to DIR? Hard to imagine how, since there are divers using the DIR configuration in recreational and tech, cold and warm, cave and wreck, safety diving... >> Could this be equally applicable to DIR? > > Hard to imagine how, since there are divers using the DIR configuration > in recreational and tech, cold and warm, cave and wreck, safety diving... Ok, so you're saying the the no-computer but comprehensive dive planning methods of DIR are the most appropriate technique for shallow warm-water recreational diving? Signature"If a man empties his purse into his head, no man can take it away from him. An investment in knowledge always pays the best interest." - Benjamin Franklin > Ok, so you're saying the the no-computer but comprehensive dive planning > methods of DIR are the most appropriate technique for shallow warm-water > recreational diving? Sure, why not? The laws of physics don't change, the rate of on-gassing, off-gassing all the same. Of course, DIR doesn't actually say ``no computer''. The recommendation is that you learn about decompression theory and then rely on what your body and the computer in your head are telling you, rather than just a dive computer. And of course, the more aggressive the profile, the more important it becomes. That's a tall order for your average recreational diver. But then, I think that what keeps many vacation divers safe is that they follow the dive plans set by the divemasters on the boat, who in turn are following the dive plans collected by the industry. Furthermore, I bet that most experienced divers who do rely on in-water computers are rarely surprised when the thing beeps at them. Their knowledge of deco has accreted over time, learned in part from the very computers they rely on. Replace it with a bottom timer and I'd bet a lot of them could go and do the same profiles they had been doing, because they are aware of what the limits are. Whistler <whiNstOler@sSan.rPr.cAomM> pounded away at his keyboard resulting in: : Replace it with a bottom timer and I'd bet a :lot of them could go and do the same profiles they had been doing, :because they are aware of what the limits are. To an extent. In fact I've done it myself on rare occasions. But I'd wouldn't make a habit of it. Dan Bracuk If we don't succeed, we run the risk of failure. > Furthermore, I bet that most experienced divers who do rely on in-water > computers are rarely surprised when the thing beeps at them. Their > knowledge of deco has accreted over time, learned in part from the very > computers they rely on. Replace it with a bottom timer and I'd bet a lot > of them could go and do the same profiles they had been doing, because > they are aware of what the limits are. I ride mine up and down like a dirtbike. >> Could this be equally applicable to DIR? > > Hard to imagine how, since there are divers using the DIR configuration in > recreational and tech, cold and warm, cave and wreck, safety diving... Oh, yeah. Just like MS Windows is everywhere... >>>Could this be equally applicable to DIR? >> [quoted text clipped - 4 lines] > > Just like MS Windows is everywhere... Well, I'd say it's much more like Linux, popping up where people who have the inclination and know how have turned to a simpler, more maintainable, more robust solution. But even that analogy is a stretch, I think. >>>>Could this be equally applicable to DIR? >>> [quoted text clipped - 10 lines] > > But even that analogy is a stretch, I think. :-) >>>>The weight is also streamlined with the body rather than creating more >>>>bulk across the hips and belly. More drag equals more effort. [quoted text clipped - 7 lines] > I've done likewise. But I did say "generally", which suggests that we > don't spend our entire flipping dive swimming against currents. But it does happen, so there's no point in ignoring it. ``Generally'', being prepared to move efficiently is a good thing. >>>>In addition, a backplate/harness configuration allows one to properly >>>>diaphragmatically breath, rather than restricting the breathing like a [quoted text clipped - 15 lines] > outward, so the only direction it had to go was in. This simple > equipment error is a training shortcoming, not an equipment shortcoming. Well, you're the first I've ever seen defend it. And you didn't convince me. Bad design, moving your arms out from your body, changing the position of things you need to get to, etc. >>>>By far the most comfortable is a backplate/harness. >>> [quoted text clipped - 15 lines] > generally requires you to have both hands free and usually requires you > to briefly dunk your head. Oooh, scary thing to do at the end of a scuba dive. > Both hands free means that you're probably losing contact with the chase > boat and/or its tag line at least momentarily. A head dunk means that > you're probably losing sight of the chase boat, which Mr. Murphy will > use as an opportunity to try to move the boat to bonk you (head injury > risk). Losing sight? Your head is down for about a second. And no, you don't need both hands. Grab the rope or ladder with one, pull with the other, then switch. > Since you will first want to hand up your weights (and camera), to then > minimize the risk of getting your head bashed, you'll have to release > and back off, which then will require a second approaches by the chase > boat instead of one, which is a risk of injury from the boat prop, etc. No, you don't release, you just take it off. > ..and it takes significantly longer too. There's few things more fun > than floating in rough water waiting for your turn to board and watching > a buddy team struggle for literally 10 minutes to get onboard the boat > because they didn't really think through their gear configuration for > the expected conditions (rough & windy). I did a bunch of dives in the Baja this way. Pop weight belt, hand off. Pop waist belt, pull, hand off. It was easy, even in current and waves. > What this all boils down to is that the lack of an alternative to ditch > your gear means that your dive exit plan includes by necessity a period > in which you will have to lose sight of and lose contact with the chase > boat. Sorry, I gotta call bullshit on that one. > So while you can dive with 'loose' shoulder loops and slip off this way, > but it is still not going to be As Quick, or As Easy as popping a QD, > and it carries other trade-offs. There is no such thing as a free lunch. Sorry Ned, I ain't convinced. > ... ``Generally'' being prepared to move efficiently is a good thing. Generally, it is. But its just one more variable in the overall trade-off. For example, we wouldn't allow efficiency to override safety. > > ... This simple equipment error is a > > training shortcoming, not an equipment shortcoming. > > Well, you're the first I've ever seen defend it. IIRC, it was really a topic of discussion circa 1980-85, along with its accompanying new invention, the power inflator. IIRC, a big part of its appeal was simplification, as it had significantly reduced complexity in comparison to the alternatives of the day, because it integrated a bladder onto a backpack...that all used to be two full sets of straps. Contemporarily, we've reintroduced some of the old BP/W's degree of complexity by having the wing removable from the plate, but we now claim that its a feature called "modularity". Fortunately, they didn't revert as far as to the "each gets its own" strap system. > And you didn't convince me. Bad design, moving your arms out from > your body, changing the position of things you need to get to, etc. Over the past three decades, I've found no significant difference in my ability to cross my arms tightly in front of me, or to carry my camera between Jacket, Wing or even Horsecollar, due to supposed 'bulk'. > > The basic risk being introduced with the "pull over head" is that it > > generally requires you to have both hands free and usually requires you > > to briefly dunk your head. > > Oooh, scary thing to do at the end of a scuba dive. Your sarcasm is noted. However, when you do a dunk like this and your instant UW view is that the chase boat's outboard motor revving and its prop looking hungrily at your legs, you too just might change your mind about how you've been doing things. This is what really prompted me to change my boarding procedures for small chase boats: boat props do kill divers every year. > Losing sight? Your head is down for about a second. And no, you don't > need both hands. Grab the rope or ladder with one, pull with the other, > then switch. That's what I thought too. However, the above experience was an "only for just a second" event, and it was not a adequate solution for that day's conditions. Wolf Island, Galapagos is a mixing bowl of rough chop, stiff winds, swirling currents and sharp rocky cliffs...not an easy place for a chase boat to manouver to pick you up. For that matter, Bequia in the Caribbean isn't reliably a cakewalk, either. FWIW, its been through such experiences that I personally place higher significance than most divers on being set up to do long (30+ minute) surface floats at a minimal energy exposure ("survive 'til they arrive"). > > Since you will first want to hand up your weights (and camera), to then > > minimize the risk of getting your head bashed, you'll have to release > > and back off, which then will require a second approaches by the chase > > boat instead of one, which is a risk of injury from the boat prop, etc. > > No, you don't release, you just take it off. If I have to doing anything that distracts me from watching the diveboat, I back off a 'safe distance', which I'd roughly define as the distance that that boat's likely to move in the next 15-30 seconds, or roughly twice as long as I expect the distracting task to take. This means that the only time that I won't physically back off from a diveboat is when it is a stereotypical Caribbean 50ft diveboat sitting on a mooring on a dead calm, dead flat Caribbean day, because under those conditions, the boat's not going to move more than 6 inches. Otherwise, I'll back off, "reset", and then make a new, safe, approach. > > ..and it takes significantly longer too. There's few things more fun > > than floating in rough water waiting for your turn to board and watching [quoted text clipped - 4 lines] > I did a bunch of dives in the Baja this way. Pop weight belt, hand off. > Pop waist belt, pull, hand off. It was easy, even in current and waves. In addition to conditions, a lot will depend on the skill of the chase boat operator. I agree that its generally not that hard, but the finesse is to limit the time that you're reducing the manouverability of the boat in the waves/winds/currents conditions...generally, the worse it is, the less time you should constrain the boat. It can get ugly if the divers don't realize that they're on the chase boat's downwind side. >> What this all boils down to is that the lack of an alternative >> to ditch your gear means that your dive exit plan includes by >> necessity a period in which you will have to lose sight of and >>lose contact with the chase boat. > > Sorry, I gotta call bullshit on that one. Well, I was assuming that you wouldn't cut your gear off of you after each dive. And you are correct that you can shuck off without QD's without "letting go" of a boat's tag line. However, since you can't push a string, I don't really consider any line from a boat to really be fully "in contact" with the boat. And since I've seen 4ft long dive ladders on the sterns of ~50ft diveboats lift fully clear of the water in rough seas, I'm not about to try such antics there. Get in fast, get out fast. -hh > Get in fast, get out fast. Agreed. I have noticed all the issues you mentioned, but they have not bothered me with any of the boats I've used, but they've all been 20' or greater and I gather you are talking about zodiac size. Perhaps I'll chnage my tune when I have to deal with that, but I doubt it. I move more slowly than other people anyway, but I don't think I was unduly slow getting out of the water on the Baja trip. > > Get in fast, get out fast. > > Agreed. I have noticed all the issues you mentioned, but they have not > bothered me with any of the boats I've used, but they've all been 20' or > greater and I gather you are talking about zodiac size. Yes, it was "downsizing" to diving off of a small zodiac that woke me up...they're very shallow draft and light, so they get very easily blown around in the wind. Probably a good rule of thumb is: 'the smaller the boat, the faster it can move on you.' What's likely to compound this is that if the operator is using really small boats, it could be because he's cheap, or it could be because the dive location isn't suited to bringing in a bigger boat. For the latter, this generally suggests that you're diving in closer to shore/rocks/shoals, perhaps within more confined areas (channels, passes, etc). All in all, less room to,manouver, which means that the boat needs to turn more aggressively and more often...like a hummingbird. Which simply compresses the effective timeline for diver recovery. -hh FWIW, I just came back from my first day of diving my new Dive Rite. It was a one tank tank dive, but a fairly long one (95 mins) with several surface swims in shallow water (stone crabbing). I had no problem with slightly adjusting my body attitude and finning to maintain myself vertically, though it does require slight effort. Note that I do any distance surface swimming while on my back and had no problem there since I actually rode higher in the water. My $0.02: I love it so far. >> Much of it is about trim and balance. > [quoted text clipped - 6 lines] > ><snip> |
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