Twins with only drysuit for buoyancy

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Melicertes

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Scuba Instructor
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I am strictly warm water these days.

But when I used my dry suit regularly (it hangs in a lonely corner of the basement now) I never bothered with any BC. Get a basic hard backback and just use that. There is probably one in your ScubaPro jacket. Or buy one used somewhere if cost is an issue. I always had that sort of set up with my doubles anyway. All you need is the inflation in the drysuit.

If the drysuit has any neoprene in it you are going to float like a cork anyway.
Ok, now I've never dived twins before and it's probably not going to be soon that I venture into that territory either, but diving twins and only using a drysuit for buoyancy control just somehow seems like taunting fate in some way to me.

I should mention that I dive my ds with my bp/w setup and only use the wing for buoyancy control because using the ds for buoyancy is just cumbersome IMHO. So the "throw out the BCD" idea is very much counter intuitive for me.

Can anybody give me a little more reasoning behind why a drysuit only would be considered sufficient and/or why a BCD should be used, if for nothing else as a backup for the ds?
 
That's kind of what I was thinking. Just wondering if I'm missing something here :wink:
 
I had to use the drysuit for buoyancy control as part of Advanced Nitrox/Deco class (to simulate what to do in case of a failed wing)....that sucked! All I had to do was dump my wing and ascend using just the drysuit...it was amazing how much air I had to keep in my drysuit. I couldn't imagine having to conduct a whole dive that way.
 
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A drysuit makes for a piss poor BCD and the excess gas required for floating a set of doubles adds nothing to the thermal properties.

So...there is no point in using your drysuit to control buoyancy of doubles during normal diving.
 
Can anybody give me a little more reasoning behind why a drysuit only would be considered sufficient and/or why a BCD should be used, if for nothing else as a backup for the ds?

With twins you have twice the weight of gas than normal. That requires twice the volume of gas to achieve neutral buoyancy at the start. That in turn means a much much larger bubble of air in the drysuit to move around, become unstable and increased risk of inversions and so on.
 
Yep, pretty much what I was thinking. It sounds to me that I wasn't entirely off base to think that this is just a stupid idea. Not having any experience in diving twins and only relatively recently having started diving drysuits, I just thought it prudent to get some other opinions.

You ask, you learn :eek:)
Thanks for the responses.
 
I don't even like to use my drysuit for buoyancy when diving a single tank. I feel like I have far less control and it just doesn't feel comfortable for me. The advice in the quote in the OP is, in my opinion, crap. A drysuit is to keep you dry and warm; a wing is to aid in buoyancy.

With twins, you'd need even more of a bubble to keep you neutral....so if the amount of bubble required to keep my single tank (HP130) neutral while just using the drysuit is uncomfortable, I can't even imagine doing that with doubles. I do like that bamamedic's class required them to simulate a wing failure and use just the drysuit for buoyancy....that way you know it can be done, but is not your best option.
 
When people dive twins with a wetsuit, they have a dual bladder wing as redundant buoyancy, Why would you use just a dry suit and no back up buoyancy? Ask yourself that question.

Unless you're using twin 40's I don't think you're going to perform a controlled swim to the surface (and stay there) if you have a failure, unless you have an oral inflator hose on your dry suit?!?!?!

Sounds like an accident waiting to happen.
 
When people dive twins with a wetsuit, they have a dual bladder wing as redundant buoyancy, Why would you use just a dry suit and no back up buoyancy? Ask yourself that question.

Unless you're using twin 40's I don't think you're going to perform a controlled swim to the surface (and stay there) if you have a failure, unless you have an oral inflator hose on your dry suit?!?!?!

Sounds like an accident waiting to happen.
Actually...thats not the reason for the dual bladder.

A drysuit pretty much has consistent buoyancy characteristics throughout the entire water column. Wetsuits are buoyant near the surface but have almost no buoyancy at depth. Add the weight of your gas into the equation a damaged wing would be catastrophic.

or another way of thinking about it.

with a drysuit, a diver will be negative by the weight of his gas alone. A wetsuit diver will be negative by the weight of the gas and the loss of buoyancy of his/her wetsuit.
 
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