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Scuba Forum / General / November 20065 Gallon Pail, Back Inflation & Aluminum, G-O Diving
As someone recently pointed out, you can estimate the amount of weight required for drysuit underwear by packing the suit in a bucket and translating the volume at 8 pounds per gallon. I did just that and wore two full sets of underwear on the 123 minute Sunday dive in 46 degree water. The first set of underwear is Thermolite and Polartec. It filled the five gallon plastic container. That indicated forty pounds were required. The next underwear is Polartec and appeared to be about two gallons. Total then is 56#. That's a lot of lead. I borrowed a couple sixes and had a couple 8's and a couple 5's. I packed an 8 and a 6 in each of the Dive Rite pockets, put one 5 in my right leg pocket of the dry suit and zipped the other 5 inside the dry suit on the opposite side. I sank like a rock even with all the underwear. G-O diving is short for grossly over-weighted diving. That's where you sink fast enough to break two ear drums on the descent and two legs hitting the bottom. To offset weight air is added. When you are G-O diving the volume of air change is significantly more with relatively minor changes in depth. Go up and little and you start to rise because the air has expanded greater than "normal." Go down a little and you find yourself kissing the bottom. It's harder to control your buoyancy. I added air to become neutral, adjusted to the situation, and took off for the other end of the lake. Two hours and three minutes later I surfaced quite warm and comfortable except for my right hand and forearm. My dry glove was leaking when I entered the water. If it hadn't been for that I would have been toasty warm and dry. I ended up carrying the spear gun and flag reel in my left hand and that hand wasn't even cold. Visibility was perfect - best I'd ever seen it. I could have stayed in another hour based on my air supply but my right hand was too cold. I knew the glove was shot too because I pinched it pulling the bands of a speargun on a previous dive. Back inflation is nothing to mess with if your not experienced. It can push you forward big time with an aluminum cylinder and weight in the front - like the Dive Rite pouches. The bigger the bladder and more weight involved the more you will be pushed face down. Remember to keep your regulator in your mouth if it happens to you. The five gallon pail to estimate weight required is a good idea. Plenty of insulation is a super idea. (The warm water weenies are drooling now.) > As someone recently pointed out, you can estimate the amount of weight > required for drysuit underwear by packing the suit in a bucket and > translating the volume at 8 pounds per gallon. I did just that and wore two > full sets of underwear on the 123 minute Sunday dive in 46 degree water. Hi Ben! Good report! I'm glad it wasn't a boat dive over deep water! (Or was it?) 8^) Hopefully, when you say "packing" the suit, it means that you actually compressed the underwear down after stuffing it into the bucket, thus reducing its volume about 1/3, depending on the compressibility of the material. > The first set of underwear is Thermolite and Polartec. It filled the five > gallon plastic container. That indicated forty pounds were required. The [quoted text clipped - 4 lines] > other 5 inside the dry suit on the opposite side. I sank like a rock even > with all the underwear. Yes, that is a lot of lead. Did you close your exhaust vent down a bit to retain air more easily? > G-O diving is short for grossly over-weighted diving. That's where you sink > fast enough to break two ear drums on the descent and two legs hitting the > bottom. Now you're scarin' me... Kinda nice being able to walk on the bottom without a hardhat, though, right? Surf surge be damned! 8^) When I described this method of estimating a starting point for weighting, I was hoping to convey the need for in-water fine-tuning (or gross-tuning, in this case). Shallow water shore entry is good for this. Was it a boat dive? I'm curious, did you get into the water and then shed some weights to determine the _minimum_ needed to get to neutral with the full tank? Then you could adjust the weighting for any expected change in tank buoyancy when empty. > To offset weight air is added. When you are G-O diving the volume of air > change is significantly more with relatively minor changes in depth. Go up > and little and you start to rise because the air has expanded greater than > "normal." Go down a little and you find yourself kissing the bottom. It's > harder to control your buoyancy. I added air to become neutral, adjusted to > the situation, and took off for the other end of the lake. You've found one of the major drawbacks to being overweighted in a drysuit. Another is the increased wasted air because of larger amounts of air used to adjust when changing depths quite often. Another is an out-of-control buoyant ascent because your exhaust valve can't vent quickly enough. More insulation means more air, so these problems go with it. Overweighting just increases the problem. I accept those drawbacks, since my typical 5-lb overweighting gives me significantly more warmth. It's not hard to manage and it's not to the point of causing any air-shifting problems. My air consumption is higher. Steel 120. By the way, did you notice any air-shifting problems, such as might affect your trim? > Two hours and three minutes later I surfaced quite warm and comfortable > except for my right hand and forearm. My dry glove was leaking when I [quoted text clipped - 4 lines] > hand was too cold. I knew the glove was shot too because I pinched it > pulling the bands of a speargun on a previous dive. Beautiful! Warm is wonderful, isn't it? Two hours in 46 degree water is super. You'll find ice-diving a lot of fun now, perhaps without needing much more thermal protection than you just used. Chest pads may be a help. The pressing of the water on my chest when horizontal tends to make that area of insulation less effective, so I loft it up with more layers. I might even try some kidney pads sometime, but I've usually got a good layer of air on that upper surface, so it's not often a cold spot. Now I'm curious to hear how much you were actually overweighted. When the tank was near empty and 4 lbs buoyant, did you still feel grossly overweighted? Any idea how much? Did you test it by removing weights? If you're an average-sized guy, I'm going to guess you might have gone with 45 lbs, judging from your description of your "Pipin" descent. > Back inflation is nothing to mess with if your not experienced. It can push > you forward big time with an aluminum cylinder and weight in the front - [quoted text clipped - 4 lines] > The five gallon pail to estimate weight required is a good idea. Plenty of > insulation is a super idea. (The warm water weenies are drooling now.) Seriously, thanks for the report. I'd like to hear more about the dive. Was it a boat dive? Saltwater? Max depth? Anchor line? Less tendency to cramp since you were warmer? Regards, Dave C PURE TALC: Source, supplier of unscented, oil-free, USP grade PURE TALC, ideal for use on drysuit latex seals. If interested, please see my talc offerings on eBay (eBay ID: dave4868). Thank you! (snip)> > Chest pads may be a help. The pressing of the water on my chest when > horizontal Eh? (snip) > (snip)> > > Chest pads may be a help. The pressing of the water on my chest when [quoted text clipped - 3 lines] > > (snip) (Louder) Chest pads may be a help. The pressing of the water on my chest when horizontal tend to make that area of insulation less effective, so I loft it up with more layers. Can you hear me now? 8^) The lowest areas (depending on position) get the compression from water, compacting the insulation there, but upper areas don't get compacted because the migrated air has allowed the insulation to retain full loft. Have you noticed which areas get cold when diving in real cold water? Like 3 or 4 degrees C? I lay some fleece material over my chest which retains enough loft even when compacted. It's warmer. Works nicely without adding unnecessary undergarment elsewhere, like using a vest instead of a jacket. Dave C PURE TALC: Source, supplier of unscented, oil-free, USP grade PURE TALC, ideal for use on drysuit latex seals. If interested, please see my talc offerings on eBay (eBay ID: dave4868). Thank you! > > (snip)> > > > Chest pads may be a help. The pressing of the water on my chest when [quoted text clipped - 9 lines] > > Can you hear me now? 8^) Eh? The water presses more on your chest than anywhere else on your body? > The lowest areas (depending on position) get the compression from > water, compacting the insulation there, but upper areas don't get [quoted text clipped - 3 lines] > Have you noticed which areas get cold when diving in real cold water? > Like 3 or 4 degrees C? Every part of me was cold! I couldn't even tell I had my reg in my mouth other than I was still breathing. I got water in my mask and my contact lenses froze up. I'm thinking that water pressing sensation you are getting is ice. > I lay some fleece material over my chest which retains enough loft even > when compacted. It's warmer. [quoted text clipped - 7 lines] > TALC, ideal for use on drysuit latex seals. If interested, please see > my talc offerings on eBay (eBay ID: dave4868). Thank you! > > > (snip)> > > > > Chest pads may be a help. The pressing of the water on my chest when [quoted text clipped - 11 lines] > > Eh? The water presses more on your chest than anywhere else on your body? Poor description on my part. This is the mechanical compressing of the suit material because the air has migrated out of the lower areas, I assume because of the slight pressure difference at the slightly deeper depth. Less loft (air) makes it colder there, meaning the chest and other frontal areas, when horizontal in a prone position. Do I have the physics right? > > The lowest areas (depending on position) get the compression from > > water, compacting the insulation there, but upper areas don't get [quoted text clipped - 3 lines] > > Have you noticed which areas get cold when diving in real cold water? > > Like 3 or 4 degrees C? > Every part of me was cold! I couldn't even tell I had my reg in my mouth > other than I was still breathing. I got water in my mask and my contact > lenses froze up. 8^) > I'm thinking that water pressing sensation you are getting is ice. That's only when I invert and crawl along the bottom of the ice for a goof! Dave C > Hopefully, when you say "packing" the suit, it means that you actually > compressed the underwear down after stuffing it into the bucket, thus > reducing its volume about 1/3, depending on the compressibility of the > material. That's right. It didn't really compress much even with quite a bit of pressure. I suspect that wearing the underwear and being compressed by surrounding water is more efficient for compression. > Did you close your exhaust vent down a bit to retain air more easily? Yes. I'm cautious when doing this but I made several adjustments while staring at the sand. > I'm curious, did you get into the water and then shed some weights to > determine the _minimum_ needed to get to neutral with the full tank? No. No adjustments no testing. I knew as long as I could stay down with all the insulation I could manage the buoyancy. If it had been too bad I would have canned the dive right at the start. > By the way, did you notice any air-shifting problems, such as might > affect your trim? No. The underwear sucked up the air. It wasn't bubbled anyplace that I could tell. Sometimes the air will balloon in the shoulders or elsewhere. I do not recall any ballooning or air shifting. > Beautiful! Warm is wonderful, isn't it? Sure beats cold. > Seriously, thanks for the report. I'd like to hear more about the dive. > Was it a boat dive? Saltwater? Max depth? Anchor line? Less tendency to > cramp since you were warmer? It was a shore dive in fresh water. I entered at public access and swam over the weeds before venting the bladder air and kissing the sand. That's in about 12 feet of water. I adjusted the exhaust valve, washed the inside of my mask, and descended to 25 feet. At 25 feet I adjusted trim by again adjusting the exhaust valve a couple more times. At this point I was looking for rough fish and ready to go. I stayed above the thermocline looking for fish. Maximum depth was 33 feet. Most of the dive was spent between 25 and 30 feet but I did spend about 20 minutes at 20 feet. I didn't find anything I could shoot. I did pick up a drivers license and passed on a lure with a nice hook set because I didn't have anyplace except my dry suit pocket to store it. I swam constantly, got leg cramps, saw a boat, cash register, computer, and some interesting bottom structure. According to the computer I had an hour worth of air left when I surfaced. Cramping was the reason I got out. I don't usually swim that much but usually get cramps after an hour. On this dive it was almost two hours before I started to get cramps. I attribute cramping to position as much as cold, but don't really know the reason. Buoyancy was still very negative but don't know by how much. My weight selection for the dive did not lend itself to adjustment. The 8# and 6# were in the weight pouches while one 5 was in the dry suit pocket and the other zipped in the suit. If I had wanted to adjust weight I would have used 2's and 3's and put them someplace else. All in all it was a really good dive. Completing a dive with both sets of underwear on makes it a success. Two times before I tried both sets of underwear without success. The weighting made the difference. I only tried it again because of your post. A few times I've found stuff on the bottom that I've hauled back. One item was a 29 pound, cast, scissors anchor with 100 feet of line. (Nearly drowned lifting that up on a pier.) Another item was a foldable, aluminum, boat ladder. When you find things like these you get to practice buoyancy swimming them to the surface. > > Hopefully, when you say "packing" the suit, it means that you actually > > compressed the underwear down after stuffing it into the bucket, thus [quoted text clipped - 4 lines] > pressure. I suspect that wearing the underwear and being compressed by > surrounding water is more efficient for compression. Ben, I agree, I think that's what happens. Each fold of the material adds space that wouldn't be there when worn. It's not too bad with fleece, but it's significant with nylon fabric lined undergarments with heavier seams. The error of this procedure increases quite a bit with larger, stiffer garments. > > Did you close your exhaust vent down a bit to retain air more easily? > > Yes. I'm cautious when doing this but I made several adjustments while > staring at the sand. 8^0 You really were pinned by the overweighting! Good thing it wasn't a silt bottom! Our grey-brown jello would have swallowed you up! > > I'm curious, did you get into the water and then shed some weights to > > determine the _minimum_ needed to get to neutral with the full tank? > > No. No adjustments no testing. I knew as long as I could stay down with > all the insulation I could manage the buoyancy. If it had been too bad I > would have canned the dive right at the start. Smart. > > By the way, did you notice any air-shifting problems, such as might > > affect your trim? > > No. The underwear sucked up the air. It wasn't bubbled anyplace that I > could tell. Sometimes the air will balloon in the shoulders or elsewhere. > I do not recall any ballooning or air shifting. Doesn't sound any worse than the inch of air I might have above my shoulders when vertical. When it starts forcing its way out of one's neck seal, it's certainly time to reduce weight. ;^) > > Beautiful! Warm is wonderful, isn't it? > [quoted text clipped - 15 lines] > passed on a lure with a nice hook set because I didn't have anyplace except > my dry suit pocket to store it. That's my kind of dive! Finding treasure and hunting! What do you shoot, carp? I'm sure I get laughed at for bringing so much gear with me, but I tuck a little plastic pencil box under a bungie on my weight belt for fragile or sharp items. > I swam constantly, got leg cramps, saw a boat, cash register, computer, and > some interesting bottom structure. According to the computer I had an hour [quoted text clipped - 7 lines] > other zipped in the suit. If I had wanted to adjust weight I would have > used 2's and 3's and put them someplace else. Excellent air consumption, I must say! The cramping sounds about like my pattern. Worse on the second dive, too. Did your computer give that 1-hour estimate of air based on the depth at the surface and breathing rate? An hour at a shallow depth might only require 20 cubic feet of air, but how much was actually left in the tank? Two hours in chilly water, finning all the time is super. > All in all it was a really good dive. Completing a dive with both sets of > underwear on makes it a success. Two times before I tried both sets of [quoted text clipped - 6 lines] > boat ladder. When you find things like these you get to practice buoyancy > swimming them to the surface. I've always been leery of using my own buoyancy to suspend a heavy object, for the obvious reasons. Here's where another of my unusual gear comes in handy; I always dive with a tuna ball (round 18" float) to which I attach my flag line. The flag itself is on a 2-foot tether to the ball. That has made it easy to bring back anchors up to 60 lbs, not to mention downrigger balls and even a like-new mountain bike once. This tuna ball rig is the same we use to support a bag of scallops just off the bottom. It's also the reason I made a Lexan line handle- the plastic ones would fold over on themselves when the heavy item was attached to the clip. I also bring along a 100-lb lift bag to send bigger stuff to the surface, tethered to my flag line, but don't want to routinely do that because of the risk of it coming down on me during the dive. Thanks for sharing the interesting details of your dive. Dave C PURE TALC: Source, supplier of unscented, oil-free, USP grade PURE TALC, ideal for use on drysuit latex seals. If interested, please see my talc offerings on eBay (eBay ID: dave4868). Thank you! http://myworld.ebay.com/dave4868 > As someone recently pointed out, you can estimate the amount of weight > required for drysuit underwear by packing the suit in a bucket and > translating the volume at 8 pounds per gallon. My impression was that this method was suggested to estimate relative changes in bouyancy from changes in thermies...ie, along the lines of 'if thermie set#2 was 2 gallons larger than the normal set, then use 16lbs as a starting point'. > The first set of underwear is Thermolite and Polartec. It filled the five > gallon plastic container. That indicated forty pounds were required. The > next underwear is Polartec and appeared to be about two gallons. Total then > is 56#. That's a lot of lead... I sank like a rock even > with all the underwear. How many pounds do you figure you were overweighted by? -hh > How many pounds do you figure you were overweighted by? I don't know. I think I could have taken 10# off without a problem. Next time I go, that's what I'll try. I'm sure I'm going to keep diving with more insulation, so now it's just to fine tune what I know can be done. I have to admit I did not read the tread completely but it seams you must of carried the full calculated weight needed by the displacement of the thermals. You need to also calculate the negative and positive weight components that you carry in your gear. Steel tanks are negative by 3 - 7 lbs. Your regulators gauges reels BCD Plate fins mask etc all contribute to your weight and trim needs. Most dry suit divers also wear ankle weights. At the point when you enter the water you should of do a weight check. all air out and exhale, you should hang with the water halfway across your face. That would make you neutral at the surface. Then add a pound or two if you descend without a line. If you do use a line then your ready to go, just pull yourself down till your soft stuff compresses and your negative. I dive a tri-lam with steel doubles reels bags computers canister light etc. I do not need any lead. If I leave the light behind I add 5 lbs to my harness and all is good. John >> How many pounds do you figure you were overweighted by? > > I don't know. I think I could have taken 10# off without a problem. Next > time I go, that's what I'll try. I'm sure I'm going to keep diving with > more insulation, so now it's just to fine tune what I know can be done. > At > the point when you enter the water you should of do a weight check. all air > out and exhale, you should hang with the water halfway across your face. > That would make you neutral at the surface. Then add a pound or two if you > descend without a line. If you do this with full tanks you will be light for your ascent, when your tanks are lighter. You need to be able to hold the last deco or safety stop. That means you need to be heavy at the beginning of the dive by the amount your tanks will swing. Your safety or deco stop will be at 10 feet or deeper the water pressure will compress the suit and undies enough to off set the swing in steel tanks. If you dive aluminum that's a whole different ball game. But why would you, With a dry suit you are already positive. Why add more positive in the easiest place to be negative. Dry suit divers should be using steel tanks and backplates as primary weight sources. and once again this is only a starting point. A first dive without proper weight adjustment should be planed to prevent any deco needs. Starting out neutral and then adding 2 - 5 lbs to ensure the safety stop is a lot easier then blindly strapping on 35 or 40 lbs (5 gal bucket at 8 lbs/gal)of lead and jumping in. If I were to do that with my gear configuration I would be 40 lbs overweight. >> At >> the point when you enter the water you should of do a weight check. all [quoted text clipped - 8 lines] > safety stop. That means you need to be heavy at the beginning of the > dive by the amount your tanks will swing. The swing in tank weight is about the same for all tanks. If you use a rule of thumb that every 10 ft3 of air will lose 1# you'll be about close enough. If you use an aluminum 80 and suck it dry you'll have 8# less at the end of the dive. If you use a steel 80 and suck it dry you'll have about 8# less at the end of the dive. The difference is that the steel tank will probably still be negative while the aluminum tank probably will be positive. For my type diving I see no good reason to use aluminum tanks. Their best quality is they are cheaper to buy. > Your safety or deco stop will be at 10 feet or deeper the water pressure > will compress the suit and undies enough to off set the swing in steel [quoted text clipped - 21 lines] >> safety stop. That means you need to be heavy at the beginning of the >> dive by the amount your tanks will swing. >>snip<< > For my type diving I see no good reason to use aluminum tanks. Their best > quality is they are cheaper to buy. And for a lot of people, that is a concern. I still dive with my double AL80's. Oh, I have to carry more lead (20lbs in DUI weight and trim harness) and the backplate is SS as opposed to aluminum with the 98's. With the 98's, 10lbs. > Your safety or deco stop will be at 10 feet or deeper the water pressure > will compress the suit and undies enough to off set the swing in steel > tanks. I guess it depends on the type of drysuit and underwear - the trilam/polartec I use doesn't compress enough to be noticable. I also like to be heavy enough at the end so I can put some extra gas in the suit for warmth on deco. Drysuit diving requires careful weighting. It's not as simple as wetsuit diving because of additional variables like trapped air and type of insulating material. The original thread told how one could adjust weighting for added insulation using a 5 gallon pail. This thread was about using the bucket to estimate the weight requirement and then using that much weight to dive with two full sets of underwear in cold water. Tank specifications are important for weighting, as you noted. The same is true of the type of plate or BC and all your gear for that matter. These variables are similar for drysuit or wetsuit. The net number is what it is and you add extra if necessary. Once you've gotten to that point what happens when you add more and more insulation? The original poster, Dave C, offered his experience with layering insulation, what insulation he used, and how he compensated buoyancy. I had tried two full sets of insulation on two other occasions without being able to stay down even after descending to 30+ feet. Whenever I added air to the drysuit it stayed in the drysuit and would not vent. The solution was more weight than I'd imagined using. After the dive I theorized using 10# less would work. That in summary is the entire thread. >I have to admit I did not read the tread completely but it seams you must >of carried the full calculated weight needed by the displacement of the [quoted text clipped - 19 lines] >> with more insulation, so now it's just to fine tune what I know can be >> done. >>snip<< > If I leave the light behind I add 5 lbs to my harness and > all is good. Yeah.. the size of that thing, you can also use it as an anchor! > I have to admit I did not read the tread completely but it seams you must of > carried the full calculated weight needed by the displacement of the > thermals. You need to also calculate the negative and positive weight > components that you carry in your gear. Steel tanks are negative by 3 - 7 > lbs. Your regulators gauges reels BCD Plate fins mask etc all contribute to > your weight and trim needs. Most dry suit divers also wear ankle weights. That just means they learned to dive a drysuit the lazy way, with a bit of practice most could do away with the ankle weights. At > the point when you enter the water you should of do a weight check. all air > out and exhale, you should hang with the water halfway across your face. [quoted text clipped - 4 lines] > not need any lead. If I leave the light behind I add 5 lbs to my harness and > all is good. Your supposed to inflate the drysuit to offset the squeeze, if your insulation is being compressed you lose insulation. Do the weight check with 500 psi of backgas and see if you can hang at 15 ft with no gas in your wing, and just enough gas in drysuit to offset squeeze. John Mason >Do the weight check with 500 psi of backgas and see if you can hang at >15 ft with no gas in your wing, and just enough gas in drysuit to offset >squeeze. The 500 psi check is good, but the depth is too much. Do it this way, and you'll be underweight. First of all, you want to be able to be neutral at 10 ft, in case you need to make an actual decompression stop (as opposed to the 15 ft safety stop). Secondly, you don't really want to bob to the surface. The ideal would be to be able to do the 30 ft per minute rate all the way to the surface. On a practical basis, if you start to become positively buoyant at 5 ft, then your final ascent will probably be okay.  SignatureRon (user ron in domain spamblocked.com) All of the suggestions for the final tuning are correct. The point is to make fine adjustments typically in the 1 -2 pound range with the now empty tank to ensure buoyancy control at the end of a dive. The original post was for the starting point of weight selection. I still say leave the bucket idea out. Get in the water, set yourself up neutral at the surface add a couple of pounds and dive. The weight that creates neutral at the surface will most likely be enough for most to be negative at 10 feet and surely at 15. The additional weight you added from surface neutral is known and will be the bulk of the weight considered for adjustment changes. If you use clip on weight or dive with a buddy you can actually remove the weight a pound at a time while hanging (hand it off to your buddy) for your deco/safety stop and find the right weight >>Do the weight check with 500 psi of backgas and see if you can hang at >>15 ft with no gas in your wing, and just enough gas in drysuit to offset [quoted text clipped - 9 lines] > positively buoyant at 5 ft, then your final ascent will probably > be okay. snip >The original post was > for the starting point of weight selection. I still say leave the bucket > idea out. Hi John. Ben summarized pretty well what I was trying to say about using a bucket to roughly estimate the weighting needed for drysuit insulation, but I think we're probably talking about different things at this point, namely 1) roughly estimating a starting point for weighting and 2) fine-tuning of weighting. I've tried to carefully describe the _limited_ value of this bucket approach, but let me add that my purpose in using it is simply to save a walk back up the beach to add weight or drop off some weight. With a hundred pounds of gear, that walk gets to be a pain. I'd rather have a little more than enough weight and be able to drop some in the water, so the dive could procede. Also, it's quite rare that this issue comes up; it's not often that one might change to a significantly different combination of insulation. You're perfectly right to just get in the water and fine-tune as needed. Personally, I've found estimating to be helpful, since I've tended to experiment a bit with different combinations of insulation for varying water temps. Since I know what weighting my base insulation requires (with a certain configuration of gear), I just need to put the added insulation in the bucket, compress it a bit and estimate what it's displacement might be. I add that amount of weight and I'm probably close enough to do the dive and tweak or fine-tune at the end of the dive. It will almost always start heavy, which saves time. Now I've got a list of what weighting was needed with the various combinations of insulation that worked well at different water temps and activity levels, so I rarely need to estimate. For me, it's going to come up again this winter because I want to add some fleece to my thighs, anterior shoulders and possibly armpits, just to see if that does the trick for low-thirties water temps- just for fun, to see if that allows a couple hours of warm bliss. I'd really like to solve the problem of major charlie horses in the backs of my thighs at the end of a second long cold dive. I hate when that happens. I'll take whatever bit of fleece I think might help, ball it up in my hands and might say, "that looks like about the volume of a 1-gallon milk container" (or paint can, etc). I'll throw on another 8 pounds of lead, hire a forklift to haul my a.s to the water and do my dive. 8^) >Get in the water, set yourself up neutral at the surface add a > couple of pounds and dive. The weight that creates neutral at the surface > will most likely be enough for most to be negative at 10 feet and surely at > 15. The additional weight you added from surface neutral is known and will > be the bulk of the weight considered for adjustment changes. snip My preference is to be neutral at the surface with an empty tank and a little more than the minimum of air in the suit, because I think it's warmer that way. I don't want to rely on squeeze to get neutral at 10 feet; squeeze on the insulation translates to colder, in my experience. -- Dave C PURE TALC - Source, supplier of unscented, oil-free, USP grade PURE TALC, ideal for use on drysuit latex seals. Offered for sale under eBay ID dave4868. Thank you! http://myworld.ebay.com/dave4868 snip >The original post was > for the starting point of weight selection. I still say leave the bucket > idea out. Hi John. Ben summarized pretty well what I was trying to say about using a bucket to roughly estimate the weighting needed for drysuit insulation, but I think we're probably talking about different things at this point, namely 1) roughly estimating a starting point for weighting and 2) fine-tuning of weighting. I've tried to carefully describe the _limited_ value of this bucket approach, but let me add that my purpose in using it is simply to save a walk back up the beach to add weight or drop off some weight. With a hundred pounds of gear, that walk gets to be a pain. I'd rather have a little more than enough weight and be able to drop some in the water, so the dive could procede. Also, it's quite rare that this issue comes up; it's not often that one might change to a significantly different combination of insulation. You're perfectly right to just get in the water and fine-tune as needed. Personally, I've found estimating to be helpful, since I've tended to experiment a bit with different combinations of insulation for varying water temps. Since I know what weighting my base insulation requires (with a certain configuration of gear), I just need to put the added insulation in the bucket, compress it a bit and estimate what it's displacement might be. I add that amount of weight and I'm probably close enough to do the dive and tweak or fine-tune at the end of the dive. It will almost always start heavy, which saves time. Now I've got a list of what weighting was needed with the various combinations of insulation that worked well at different water temps and activity levels, so I rarely need to estimate. For me, it's going to come up again this winter because I want to add some fleece to my thighs, anterior shoulders and possibly armpits, just to see if that does the trick for low-thirties water temps- just for fun, to see if that allows a couple hours of warm bliss. I'd really like to solve the problem of major charlie horses in the backs of my thighs at the end of a second long cold dive. I hate when that happens. I'll take whatever bit of fleece I think might help, ball it up in my hands and might say, "that looks like about the volume of a 1-gallon milk container" (or paint can, etc). I'll throw on another 8 pounds of lead, hire a forklift to haul my a.s to the water and do my dive. 8^) >Get in the water, set yourself up neutral at the surface add a > couple of pounds and dive. The weight that creates neutral at the surface > will most likely be enough for most to be negative at 10 feet and surely at > 15. The additional weight you added from surface neutral is known and will > be the bulk of the weight considered for adjustment changes. snip My preference is to be neutral at the surface with an empty tank and a little more than the minimum of air in the suit, because I think it's warmer that way. I don't want to rely on squeeze to get neutral at 10 feet; squeeze on the insulation translates to colder, in my experience. -- Dave C PURE TALC - Source, supplier of unscented, oil-free, USP grade PURE TALC, ideal for use on drysuit latex seals. Offered for sale under eBay ID dave4868. Thank you! http://myworld.ebay.com/dave4868 >> Do the weight check with 500 psi of backgas and see if you can hang at >> 15 ft with no gas in your wing, and just enough gas in drysuit to offset [quoted text clipped - 9 lines] > positively buoyant at 5 ft, then your final ascent will probably > be okay. Never had a problem but if you prefer to do the check at 10 ft that's fine by me John |
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