Redundant Bouyancy

[in_cavediver]

This is a great question and the reality is that there really isn't a great way to go.

1) Drysuit - easiest and most flexible but I've tried it as a primary BCD for near full dbl 104's and it was painful at best to manage. Burping gas from seals played havoc

2) Lift bag - I have tried this as well. Did the whole swim with it near me to manage the gas and the shoot it to the surface and clip the reel to me. Niether case is ideal. The keep it with you is a PIA to get neutral and maintan. The send it up is also problematic as I have an open bottom bag and would risk the bag toppling over and losing air.

3) Double wings. Never tried this but if I had to dive wet in very negative tanks, this is the way I'd go. I have no expierence with the management of the second inflator to know how much of a PIA it would be. It also adds another LP hose to manage and think through. (Connected or in the 'ready' position to connect)

Me, I have drysuit first, then lift bag as my bailouts. (and yes, I have a spare DS to use if my primary is damaged one a previous dive) On the surface, I'd do the DS first and only if it was going to be a while would I tie the tanks to the bag. I wouldn't immediately drain the gas out to reduce wieght as I might very much want that gas later. All depends on the specific circumstance.

 

[texdiveguy]

3) Double wings. Never tried this but if I had to dive wet in very negative tanks, this is the way I'd go. I have no expierence with the management of the second inflator to know how much of a PIA it would be. It also adds another LP hose to manage and think through. (Connected or in the 'ready' position to connect)

All depends on the specific circumstance.

The LP is no problem when routed correctly,,,,I am lucky in that my redundant wing that I stack is a unit with a sleeve over the corrigated inflator hose,,,,I slip my LP hose into the sleeve un-connected.

 

[scubafool]

The LP is no problem when routed correctly,,,,I am lucky in that my redundant wing that I stack is a unit with a sleeve over the corrigated inflator hose,,,,I slip my LP hose into the sleeve un-connected.

Just curious. Have you ever tested to see how long it takes to hook it up and inflate, and how far you might drop while doing so?

 

[darylm74]

Going back to the OP's question and scenario- one of the chief criticisms that I've read of dual-bladder wings is that if something is going to puncture one bladder it's just as likely that it will puncture both and your redundancy is out the window.

That aside, I've only used a dual-bladder wing once, and I found the extra inflator on the right side thoroughly annoying.

It sounds like another good reason to stick to my drysuit, with thin undergarmens in warm water, and use it as reduandant bouyancy. As stated in my original post, I have had to use my drysuit as redundancy before. I did 122 in Gilboa, had some bouyancy issues the last 30 feet, and realized at the top that I had a leaking LP thimble connection. I popped the hose, but my hands were so chilled that I had a problem tightening it down. At that point, I added some extra argon into my drysuit and haulled ***** to shore. I could have dropped weights but there were a lot of divers below me. My last choice was to drop weights if it really became a survival issue (far from it in my current view). I didn't want to drop weights on anyone, and I knew I had plenty of drysuit bouyancy, energy and power to b-line for the dock. The drysuit served me well then, and I think it would again. My question was based on the idea of doing a wetsuit in the worst case scenario. I believe that it is either a drysuit a dual bladder for me. The bag is great for hanging, but if I have to spend some time at the surface, waiting for the boat to pick me up, I'd rather have a dual bladder or be the proverbial stay-puff marshmallow man at the surface in my drysuit.

Thanks again for everyone that chimed it. It gives me a lot to think about, and I like the different perspectives. Even if I don't agree with someone, I learn from them just as well.

Daryl

 

[in_cavediver]

Just curious. Have you ever tested to see how long it takes to hook it up and inflate, and how far you might drop while doing so?

The idea is simple, you might drop a little but you should be kicking to maintain depth while attaching the hose. If you do it right, you should be able to maintain a reasonable depth for however long it takes to accomplish this task (or for your buddy to assist).

If you can't do multiple things at once, you really ought to rethink the dive and equipment your using for said dive.

 

[texdiveguy]

Just curious. Have you ever tested to see how long it takes to hook it up and inflate, and how far you might drop while doing so?

Good question of yours---.....I have never had to actually put it to the test in a real situation,,,BUT have practiced multiple times at various depths....it only takes seconds to reach the redundant inflater and attach the charged LP hose.....I am finning to reduce the drop. Remember that the extra back up wing does not ness. have to be as big as your primary....this wing is used to break/stop your decent and regain control and begin the proper ascent/stops. I use a 65lb. primary wing....my back up is 40lb. which is more than enough.

 

[MaxBottomtime]

Going back to the original post, it's been awhile since I read the Fundamentals of DIR, but one of the main rules of DIR is no steel tanks with a wetsuit.

 

[Doubles]

Going back to the original post, it's been awhile since I read the Fundamentals of DIR, but one of the main rules of DIR is no steel tanks with a wetsuit.

You might have missed that this isn't in the DIR forum - but the OP might be interested in reading info on DIR so as to have more to consider.

As to the OP's question -

I wear a Zeagle little bertha (double bladder wing). Its a single wing with 2 bladders inside and 2 inflator hoses. I wear mine with both LP hoses connected all the time. I wear this when diving both wet and dry.

Some say if one bladder were to fail the redundant would most likely fail as well. I disagree with that position on this topic. There are many things that might fail and not cause the redundant bladder to fail with the primary.

I find it hard to believe that something would likely puncture both at once - sure it's possible.

I would prefer not to use my drysuit for buoyancy, thats not the purpose it was designed for. Drysuits react slower than wings and are more difficult to manage IMHO.

You know there are many options, just be sure to practice often with the solution that you choose

Cheers

Steve

 

[GDI]

Good question of yours---.....I have never had to actually put it to the test in a real situation,,,BUT have practiced multiple times at various depths....it only takes seconds to reach the redundant inflater and attach the charged LP hose.....I am finning to reduce the drop. Remember that the extra back up wing does not ness. have to be as big as your primary....this wing is used to break/stop your decent and regain control and begin the proper ascent/stops. I use a 65lb. primary wing....my back up is 40lb. which is more than enough.

Just curious. Have you ever tested to see how long it takes to hook it up and inflate, and how far you might drop while doing so?

Scubafools question was good and it is something that you may want to test in a controlled location. Usually when divers are using redundant lift they are slinging extra cylinders. We have two conditions here now that can contribute to a problem.

1. Is Obvious that the extra weight of the added cylinders means higher negative buoyancy characteristics.

2. And that when divers do this they fail to realize that their equipment isn't configured to the normal way they would do it, under standard diving conditions; therefore lacking muscle memory and a consistant equipment set-up mind set.

It can take only a few seconds for a diver to descend on a loss of buoyancy. I have had a situation of a diver who did just that where in a matter of a few seconds the difference of depth was 80-100 feet deeper and this only because I was able to arrest the descent using redundant lift. The time it takes to reconnect a supply line is lost time and COULD put you the diver at an even greater risk: greater narcosis, HPNS, O2 toxicity, greater reduced negative bouyancy at greater depths to name a few. The problem circle keeps turning and compounding.

While the risk of an all out rupture of a bladder is minimal and the lost of a second bladder (whether it is stacked or contained in a single outer shell) is even less likely, keep in mind we don't train tech divers this way we train for worst case scenario. That means all out loss of lift from all sources

IF I can suggest: I suggest you go out and test the time it takes you to re-connect a bladder line having no buoyancy to support you. With this test, also swim your doubles and your extra cylinders up with no air in any bladder or drysuit. You might the results surprising. Repeat the test to get an average result. Do it with the extra tanks and without.

 

[Ghost69]

Great question. I too dive tec and utilize my dry suit as redundant bouyancy. Same thing, I may do my trimix in FL Keys instead of the Great Lakes. Much warmer down there so I do not plan on using my dry suit. My question is, should I use a dual bladder wing or take to single bladder wings and hook them up to my doubles? I already have two single bladder wings but I would have to go out and buy the dual bladder wings. Any thoughts?