Dual Bladder Wings - A Good Choice for Redundancy?

[MichaelMc]

You’re auto-inflating. Which bladder is it?

That’s the hangup with dual bladder wings. You can’t tell.

dirt simple in (big) steel tanks:
properly weighted
drysuit
stay in trim

in Al80s:
properly weighted
swim up

Well, I'm not as concerned about the instant descent from total wing failure as I am diving balanced. So I don't have the second inflator connected to an LP hose. So only one thing could be auto-inflating. Not the two with the dry suit.

I just like the third option, beside dry: use-the-suit or wet: swim-up, of being balanced but taking the time to plug in my extra bladder so I can hang relaxed at the safety stop. Yeah, I could hang from a lift bag. Deploying that while finning to hold some depth could be fun. My extra bladder is more easily managed. Plus I can swim out of the kelp with it. It might s*ck doing that with the lift bag.

Is that extra corrugated hose really more complex than the drysuit and its issues??
Maybe you'd rather have your ascent be an exceptional case if you’re diving wet. I'd rather not. I think we often have that debate about planning on CESA vs carrying redundant air.

(And not to stray further from the fold, but it might be there is no buddy nearby to help. There's a reason I'm diving redundant (sidemount) cylinders.)

 

[rjack321]

So, if the purpose of a dual bladder is to have a redundant lift source. When is an instance that you ever have to worry about a negative descent caused by the bladder? It will never be the bladder causing the descent, but the absence of additional lift and buoyancy control to counter the additional weight you carry in gear/lead/tank. Therefore, should the bladder be compromised, you should dump most of your ditch-able weight and swim to the surface controlling your ascent to the best of your ability. Once on the surface, stabilize using your buddy, and correct the problem or ditch the rig. In the end, should the argument not be for a balanced rig that requires no additional ballast or a substantial source of ditch-able weight? As that would be apt to cause more problems and be the more accurate solution to a compromised bladder, not including a runaway inflator that a redundant bladder will not help with.

If you are diving wet then you have two things going on:
1) You aren't that deep (<100ft) and you are in a single tank
a) these are almost always not a big deal to swim up even without ditching weight
b) wear any thickness wetsuit you want. Compression to the point of not being able to swim up is remote (but you can test it easily too)

2) You are doing a tech dive in doubles
a) the water has to be warm, period. Like 3mm or less wetsuit warm, which has almost no compression
b) warm water, barely any exposure protection? AL80s are the tanks since your consumption is also going to be lower.
c) You can swim these up from depth because they wont have air in them on a tech dive. The only "heavy" tanks you have are an Al80 of EAN50 and a 40 of 100%. Everything else has some sort of trimix in it and even full is barely negative.
d) you can swim this up in event of a wing failure.

Everything else = drysuit which covers your redundant buoyancy needs. A lot of you are overthinking this. The redundant bladder solves nothing and potentially creates problems, just leave it at home.

 

[MichaelMc]

@rjack321 I’m sure there is a world in which things line up that cleanly into two nicely separable cases.

 

[MichaelMc]

But there is.. either you have a balanced rig / enough ditch-able weight that you can swim up. If not, then dive dry.

As I said I'm sure there is a world.
In your world those are the only options and things separate that cleanly.
It does sound as if your 'dive dry' is so that you can have redundant lift.

In a different world, you might equip yourself with a redundant bladder, disconnected until you need it. And avoid those 1000' deep blue water abysses that your exploding bladder drops you into like a stone. Or equip that way while being balanced.

 

[Degenerate]

So only one thing could be auto-inflating. Not the two with the dry suit.

Is that extra corrugated hose really more complex than the drysuit and its issues??

Fun fact, drysuits made in the EU (dont know about the rest of the world) are required to have a dump valve thats more effective than the inlet valve.
So in the case of an auto inflation issue, you can just dump all the air being pushed into your suit until you can shut down the valve.
We tried this yesterday with a Santi, Ursuit and a Waterproof.
Was no issue at all really...

 

[MichaelMc]

Fun fact, drysuits made in the EU (dont know about the rest of the world) are required to have a dump valve thats more effective than the inlet valve.
So in the case of an auto inflation issue, you can just dump all the air being pushed into your suit until you can shut down the valve.
We tried this yesterday with a Santi, Ursuit and a Waterproof.
Was no issue at all really...

The issues I had in mind were not of venting an auto-inflate. But rather of diving dry in general vs. controlling a deflated redundant bladder inside your wing.

 

[kensuf]

You’re auto-inflating. Which bladder is it?

That’s the hangup with dual bladder wings. You can’t tell.

This is a good point but it has a simple solution. NEVER hook up both inflators on a dual bladder wing.

 

[wetb4igetinthewater]

Why do you think this is a good idea? Or even something worth pursuing? I mean Guy doesnt even dive sidemount... How could he teach you T 1 (or anything) in sidemount?

I meant it completely as a joke. I'm not going back to backmounted doubles. Ever. I dive sidemount to normoxic trimix levels max (200 ft/60 meters). Two primary cylinders, plus two deco bottles. Any further gas requirements means rebreather. End of story. I pretty much will only be taking 3 courses from now on. Cave with hopefully Edd. Advanced wreck with Andy Davis. Rebreather with Billy Snook. If I see a workshop that I see have value to me, then I'll take it.

 

[rjack321]

@rjack321 I’m sure there is a world in which things line up that cleanly into two nicely separable cases.

If you want to dive wrecks in sidemount
Or use a 5mm wetsuit with double steel 130s in NC for a 130ft air dive with 2 deco gases (posted in another thread)
Use dual bladder wings, jersey lines, or whatever

Really that's all fine.

GUE-F is not about any of that however. There is specific equipment for GUEs tech & cave programs that fits into a coherent whole. You can't pick and choose from it what you like or dislike without altering the whole. Which is where this whole dual bladder wing issue started. "Just putting your dual wing back on" because you feel like it is altering the whole. 1) its not needed and 2) if you do use in in lieu of the standard way of doing things your training and muscle memory is mismatched to your gear.

 

[rjack321]

I meant it completely as a joke. I'm not going back to backmounted doubles. Ever. I dive sidemount to normoxic trimix levels max (200 ft/60 meters). Two primary cylinders, plus two deco bottles. Any further gas requirements means rebreather. End of story. I pretty much will only be taking 3 courses from now on. Cave with hopefully Edd. Advanced wreck with Andy Davis. Rebreather with Billy Snook. If I see a workshop that I see have value to me, then I'll take it.

So what wing are you using? What cylinder is feeding your power inflator? And what was the specific protocol taught in your deco class for a runaway inflator? And how was this protocol proofed in the real world? - ie how did you demonstrate proficiency under stress.