Lessons Lost integrated weight pouch at depth

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wnissen

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Location
Livermore, Calif.
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I was in the middle of a lovely boat dive in Catalina with my new buddy, a steady diver with plenty of experience. We had both dived from the Dr. Bill Casino Point the day before, so our skills were reasonably sharp. On the second dive of the day, I was at about 12 m / 40 ft., in an 8/7mm wetsuit, with a steel 12 L / HP 100, 2 lb. tank weight and 20 lbs. in the integrated "Sure Lock" weight pouches of my Aqualung back-inflate Dimension BC. That amount of weight is pretty dialed in for me, no plummet on descent but no trouble staying down at the safety stop.

Everything was going great, except that I had to dump a decent amount to stay level and was having trouble dumping enough. My breathing got unconsciously shallow as I tried to avoid taking my normal slow breaths. I swiveled around to make sure all the air in the BC was at the kidney dump, dumped the remainder, and felt around to find no bubble back there at all. Then I realized something was wrong, because there should be no way I should be light at 12m with my BC completely empty. Taking the half-full tank and wetsuit compression into account, there should be a decent-sized bubble in there, at least 1-2 L. I felt around for my weights and couldn't find the left pocket. That was my first real pucker moment at depth. The last thing I wanted to do was make a buoyant ascent. I didn't try to stop, breathe, and think like I was trained, unfortunately.

I signaled "trouble" to my buddy and eventually was able to show him the missing weight pocket, though that took a while. I wasn't quite thinking clearly with the adrenaline, I should have picked up rocks immediately, because that did weigh me down enough to be perfectly stable. It was certainly lucky that we were on a rock pile and surrounded by kelp with high tensile strength. I kept real close to the bottom and my buddy, and we basically sat at the base of a 5m stalk of kelp to take our safety stop. Then I went up as slowly as I could, grabbing the kelp as needed. All in all, a very successful ascent.

Lessons learned
  1. Don't rely on Aqualung "Sure Lock" weight pouches. I did not notice losing the weights; possibly when another diver veered into me? We had 20 divers on one three-tank trip, and lost 4 weight pouches among us, all from Aqualung. The design of ditchable weight is tricky since you have an "always/never" situation where you want the weights to always be ditchable when needed, but never do so accidentally. This accidental weight release was in a very benign environment, with extra weight in the form of rocks, at a moderate depth, with kelp, and with a solid buddy. If it had been midwater, deep, no kelp, and a flaky instabuddy, the results could have been negative (no pun intended). It seems like what you really want is 10 lbs. non-ditchable and 10 lbs. ditchable in 5 lb. increments. I really can't think of a situation where you'd want to ditch it all, even if you had a busted BC, completely full tank, no hard bottom, and needed to CESA. Time to get a backplate so I can make that choice, I guess.
  2. Always check your weights and your buddy's weights before every dive, not just the first. I had checked my weights by listening for the solid "click" and pulling on them firmly at the start of the first dive and did not touch them afterwards (I notice many divers remove them to replace tanks, in which case you'd obviously have to redo the check). I don't remember doing a check immediately before the dive with the incident. My buddy gave a more than cursory check, but I don't think he tugged them either. My guess is the pouch was secure when I started the dive and just got snagged against a rock or the other diver.
  3. Always leave a good gas reserve, appropriate to the conditions. Having several minutes to resolve the problem let me calm down a bit, remember to pick up rocks, and communicate with my buddy.
  4. If you do have a Sure Lock, a spare should be part of your Save-a-Dive kit. There are two sizes, one for the jacket, the other for back-inflate, but the shorter back inflate version (that only holds 10 lbs.) fits in both. So you can save your own dive, or have your drinks bought by a grateful buddy.
 
Losing one pouch is at least better than losing a whole weight belt. But probably more common - the ocean floor is probably littered with weight pouches.

Some BCs with weight pouches also have nonditchable trim weight pockets in the back. Or sometimes people put a weight on the tank strap. It’s weight you can’t lose and may help with your trim. As far as having spare pouches, its nice if you do but not a crisis if you don’t, just using a regular weight belt is usually an available option.
 
It seems like what you really want is 10 lbs. non-ditchable and 10 lbs. ditchable in 5 lb. increments
I'd say 6 lb ditchable in 3 lb increments because you'll be 6 lbs lighter at the end of the dive -- after breathing down your HP100. If your wing fails, just drop 6 lbs to be neutral at the safety stop (with a fullish tank), 3 lbs (with half tank), or nothing if tank is at reserve pressure.

If you can't swim up after dropping the above, consider getting redundant buoyancy (DSMB, redundant bladder wing, reliable buddy, or even a drysuit) to make that a non-issue.

Without that, dropping more lead will obviously allow you to get off the bottom, but you'd be positive at some point, possibly ascending faster than desired. Basically the scenario you experienced! Options to mitigate that (without a solid buddy or available rocks) are flare or kick downward.

Another lesson learned might be to work out these possibilities now, while you have a functional BCD.
 
Losing one pouch is at least better than losing a whole weight belt. But probably more common - the ocean floor is probably littered with weight pouches.

Some BCs with weight pouches also have nonditchable trim weight pockets in the back. Or sometimes people put a weight on the tank strap. It’s weight you can’t lose and may help with your trim. As far as having spare pouches, its nice if you do but not a crisis if you don’t, just using a regular weight belt is usually an available option.

Yup my Scuba Pro Black has two pockets on the back. I place 2kg in each pocket. I also place each weight in a sock as sometimes the weights have damage that can nick and scratch at the pockets over time.
 
Losing one pouch is at least better than losing a whole weight belt. But probably more common - the ocean floor is probably littered with weight pouches.

Some BCs with weight pouches also have nonditchable trim weight pockets in the back. Or sometimes people put a weight on the tank strap. It’s weight you can’t lose and may help with your trim. As far as having spare pouches, its nice if you do but not a crisis if you don’t, just using a regular weight belt is usually an available option.
Yep, I do have those pockets, keep 2 lb. there normally with a steel. If I switched to 10 lb. / 4.5 kg up there I would only have 12 in the pouches, which is better for ditchability, both accidental and intentional. I think that's going to do bad things to my trim, though. I have a pretty good amount of "physiological buoyancy" in my belly region, so putting the weight down there makes a lot of sense, it would be pretty high above my center of mass on the tank. Worth trying in the pool, though. With aluminum it would probably be fine, but I almost always dive steel.

I could have made do with a weight belt, yes. They do tend to fall off me, I don't have much in the way of hips, so I am wary.
 
OP, check out a DUI weight harness. It has pockets you can drop. I think it would be difficult for those pockets to come out by themselves.
 
Another thing to keep in mind is that rocks are not as dense as lead. Lead is about 11 times heavier than water while limestone, granite etc are only about 2-3 times heavier than water. Hence if you lost say 10lbs (assuming the lost pocket was holding half of your 20lbs ballast weight) the rock you need to grab would be impractically big (in terms of size/volume - not necessarily weight) and require both hands to hold it.
Yes rocks are good if for whatever reason you find yourself somewhat light eg during your SS but only for a few lbs and for short periods of time unless you can somehow store them eg inside pockets.
 
OP, check out a DUI weight harness. It has pockets you can drop. I think it would be difficult for those pockets to come out by themselves.
Yep, I am looking at various harness and pocket options. It seems like it would be simpler to use one that strapped on to a waist strap, rather than a separate harness, have you ever used that style? One of my buddies has the DUI system and likes it.
Another thing to keep in mind is that rocks are not as dense as lead. Lead is about 11 times heavier than water while limestone, granite etc are only about 2-3 times heavier than water. Hence if you lost say 10lbs (assuming the lost pocket was holding half of your 20lbs ballast weight) the rock you need to grab would be impractically big and require both hands to hold it.
Yes rocks are good if for whatever reason you find yourself somewhat light eg during your SS but only for a few lbs and for short periods of time unless you can somehow store them eg inside pockets.
I have medium pockets, so I was able to fit a decent amount in there plus in one arm, so I was actually fine overall. I think there's not actually a problem with the rock being too big because the net buoyancy of 10 lbs. is all you need. So even if the rock would be too heavy to carry one-handed topside, under the water it worked fine for me.
 
Good use of kelp here. I always thought that if I was ever suddenly buoyant locally, I'd probably look for kelp (assuming I wasnt in an urchin barren) before I looked for rocks - Id hope the urchins hadnt nibbled at the roots.
 
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