DIR- Generic dual bladder wings...

[rongoodman]

Is the concern about simultaneous failure of both separate independent inflator/bladder systems? You aren’t supposed to be using both sides during the dive…

I believe the issue is troubleshooting a leaking inflator and dumping the resultant excess gas, since you now have two separate inflators and two OPVs to deal with. You can't just shut down both posts while dumping both sides. As far as I recall, the only hardware issue I've ever had was an inflator which was stuck partially open. Luckily, the leak was slow enough for me to stay ahead of and I replaced it as soon as I got back to the boat. Being forced to the surface on a recreational dive would be annoying, the same thing happening with a substantial deco obligation could be catastrophic.

 

[PfcAJ]

I don’t understand that concern either. You hook up the left inflator to a second stage like usual. You use it like you usually do, using that bladder to offset however negative you are (a balanced rig hard to achieve in doubles and a thin exposure suit). In the VERY unusual case where THAT inflator/bladder system fails open from a leaky elbow or whatever, you just add gas to the backup bladder for buoyancy, using oral inflation of the right side.

Is the concern about simultaneous failure of both separate independent inflator/bladder systems? You aren’t supposed to be using both sides during the dive…

There’s no way you’ll be able to oral inflate fast enough to compensate a sudden massive loss of wing gas. You’re toast. Your ears are toast.

Oral inflating is a 2 hand operation and you’ve got three things to do. Reg out, inflate, and clear ears. And you’re sinking while this is going on, so each breath that goes in the wing is being compressed as you descend. It’s a losing battle. Plus almost everyone seems to tuck that 2nd inflator back somewhere and it’s not immediate access.

 

[doctormike]

There’s no way you’ll be able to oral inflate fast enough to compensate a sudden massive loss of wing gas. You’re toast. Your ears are toast.

Oral inflating is a 2 hand operation and you’ve got three things to do. Reg out, inflate, and clear ears. And you’re sinking while this is going on, so each breath that goes in the wing is being compressed as you descend. It’s a losing battle. Plus almost everyone seems to tuck that 2nd inflator back somewhere and it’s not immediate access.

Dunno, others have had different experiences. I agree, there are probably some situations where that's not advisable. And I wouldn't do it with steel doubles and a light exposure suit, especially over a lethal real or virtual bottom. So if you were planning THAT dive with that configuration, then yeah, sure, just hook up the second (right) inflator to a first stage, and only touch it if you get a sudden massive loss of wing gas (i.e. the elbow falling apart) on your left side.

 

[doctormike]

I believe the issue is troubleshooting a leaking inflator and dumping the resultant excess gas, since you now have two separate inflators and OPVs to deal with. You can't just shut down both posts while dumping both sides. As far as I recall, the only hardware issue I've ever had was an inflator which was stuck partially open. Luckily, the leak was slow enough for me to stay ahead of and I replaced it as soon as I got back to the boat. Being forced to the surface on a recreational dive would be annoying, the same thing happening with a substantial deco obligation could be catastrophic.

I think that we may be overthinking this. You don't need to shut down a post to deal with an inflator that is leaking gas into a wing (the opposite problem of what we were talking about before), you just disconnect the hose.

So - steel doubles and a dive skin on a blackwater dive with a bottom at 3000 feet? Yeah, hook up that second inflator to a first stage, or just don't dive that configuration.

Other situations? The double bladder wing is simply bringing along an EXTRA wing, that shares the canvas cover with your primary wing. So you dive like you normally do, and if you find that your primary wing can't hold gas, you have a backup. 3 is 2, 2 is 1, 1 is none. And if you still find the double bladder wing to be problematic for reasons outlined here, dive dry.

It's just a simple tool that's appropriate for a very specific situation - heavy doubles and a thin exposure suit. You don't need to dive that rig, but if you do, here's a way to make it safer.

 

[PfcAJ]

Or just do it right from the jump and you don’t have these “problems”.

 

[Adobo]

None. Each bladder is connected to separate first stages. Essential for extreme depths where the water takes hold of you.


Don't forget to always carry two SMBs or one of each (lift bag) when diving deep.

Humility: they realize that they don’t know everything, and that there may be more than one right way to do something. Their ego doesn’t get in the way of learning, doing or teaching.

Open mindedness: they never reject something just because it’s new or different, and they listen to other viewpoints. They don’t fear change and they’re not threatened by differing opinions.

Analytical: they accurately and realistically weigh the merits of a technology or procedures for themselves and never accept something just because it’s new or because someone else thinks it is better. They don’t let what they like, dislike or want to believe, influence their conclusions.

Competent: while they’re open to change and alternative ways to do things, their own methodologies are solid and they can demonstrate a rationale and realistic basis for each. They’re quietly confident about how they dive, and they don’t choose their methodologies based on looking cool or what someone else might think or say.

In case you are unaware, you are in the DIR sub forum. The answers given here are coming from a very specific approach to diving.

If you want to advocate alternative approaches, you can do so in the other sub-forums.

 

[ABK]

I asked this here because I've not been entirely sold on the idea that a drysuit was any better a method of redundant buoyancy than a dual bladder wing but after this conversation I can see it. With heavy steel cylinders, stages, etc... trying to orally inflate a second bladder while in a completely negative plunge would be a nightmare. Hitting the inflator on a drysuit seems more practical.

 

[Adobo]

I asked this here because I've not been entirely sold on the idea that a drysuit was any better a method of redundant buoyancy than a dual bladder wing but after this conversation I can see it. With heavy steel cylinders, stages, etc... trying to orally inflate a second bladder while in a completely negative plunge would be a nightmare. Hitting the inflator on a drysuit seems more practical.

Depending on where you are diving, there is also the exposure protection angle.

The deeper you go, the more compressed your wetsuit, the less it will keep you warm. Gotta ask, what benefit are you getting vs what you are giving up.

 

[doctormike]

I asked this here because I've not been entirely sold on the idea that a drysuit was any better a method of redundant buoyancy than a dual bladder wing but after this conversation I can see it. With heavy steel cylinders, stages, etc... trying to orally inflate a second bladder while in a completely negative plunge would be a nightmare. Hitting the inflator on a drysuit seems more practical.

Oh, if you are OK with a dry suit, that pretty much eliminates the need for the double bladder wing. I was just pointing out that there were situations where it could be helpful.

The main downsides of a dry suit are overheating in very warm climates, cost, and failure points (like torn seals). If those aren't major considerations, dry suits are awesome. Plus... pockets!

I should point out that a double bladder wing does have some advantages over a dry suit as emergency backup buoyancy, despite the operational issues of inflation choices. It is better to have your buoyancy near the center of mass on your back, contained in a bladder than free in your suit, where bubble management is an issue. But the thing is, you won't need to add nearly as much gas if you are diving dry, because even running your dry suit tight, it has far more buoyancy than a wetsuit. Which means that it's easier to have a close to balanced rig, even with steel doubles.

The best thing by far is to have a balanced rig. If you are fairly balanced, the only reason you even HAVE a wing is to offset the weight of the gas you consume during a dive, so that you are neutral at the start of the dive with full tanks. Even in doubles, that's not going to be a huge amount of weight, hopefully you can swim that up if the wing fails, or at least slow your descent enough to avoid the lawn dart thing while you deploy whatever backup buoyancy strategy you decide on.

 

[ABK]

Oh, if you are OK with a dry suit, that pretty much eliminates the need for the double bladder wing. I was just pointing out that there were situations where it could be helpful.

The main downsides of a dry suit are overheating in very warm climates, cost, and failure points (like torn seals). If those aren't major considerations, dry suits are awesome. Plus... pockets!

I should point out that a double bladder wing does have some advantages over a dry suit as emergency backup buoyancy, despite the operational issues of inflation choices. It is better to have your buoyancy near the center of mass on your back, contained in a bladder than free in your suit, where bubble management is an issue. But the thing is, you won't need to add nearly as much gas if you are diving dry, because even running your dry suit tight, it has far more buoyancy than a wetsuit. Which means that it's easier to have a close to balanced rig, even with steel doubles.

The best thing by far is to have a balanced rig. If you are fairly balanced, the only reason you even HAVE a wing is to offset the weight of the gas you consume during a dive, so that you are neutral at the start of the dive with full tanks. Even in doubles, that's not going to be a huge amount of weight, hopefully you can swim that up if the wing fails, or at least slow your descent enough to avoid the lawn dart thing while you deploy whatever backup buoyancy strategy you decide on.

I honestly just get tired of putting on a drysuit sometimes I don't dive a dual bladder wing. I dive compliant with the DIR philosophy because it's the only tried and true method that is also standardized within a community.
This question was just kind of a "I know this is the standard but I don't understand why" kinda question.