Why do the big OMS wings have 2 inflators?

[cool_hardware52]

Up in the tropics my 3 mm needs only 5 lb of lead. My total kit therefore can only be 6-7 lb negative with no weights. If I want to use anything other than double Al 80's or tiny steels then I'm going to have to resign myself to being overweighted.

Like it or not many divers do dive big steel doubles in warm water. In this case you have to either use a lift bag for redundant bouyancy (which comes with its own set of hazards at a time when you need things to work and be simple), or just go with a redundant wing.

Keep in mind the topic of this thread, and nature of the question posed by the OP.

It was not "is there any possible use for redundant bladder wings" There may be, but I would hope by the time any diver is making dives that involve long deco hangs he isn't here asking about why some wings have two inflators........

The wings in question are both quite large, 60 and 94 lbs capacity. That leads me to conclude that they are not targeted at divers using 3mm wetsuits.

What I see happen repeatedly is the "new" tech diver, lacking a drysuit, buys a redundant bladder wing, at a cost often about 2x what a good quality conventional wing would cost.

Soon they discover that the exposures they are subjecting themselves to when diving with doubles demands a drysuit. Now they are looking for a correctly sized conventional wing. How do I know this? They tell me.

Better, and ultimately cheaper, is to start off with appropriate gear.

Tobin

 

[Tassie_Rohan]

Call me a reckless thrill seeker Tobin, but as I normally dive dry, and carry a SMB, carrying yet another redundant buoyancy source on cold water dives is, IMHO, overkill.

Still - dual bladder wings do have a place in the scheme of things. One of them warm water with a wet suit with fairly negative and non-removable kit.

Agree 100 % that new tec divers often fall into the trap of buying lots of unnecessary gear: but as a manufacturer yourself I though you would be encouraging that? You could sell them the stuff they don’t need first, then sell them the stuff they do need later.

Cheers,
Rohan.

 

[cool_hardware52]

Agree 100 % that new tec divers often fall into the trap of buying lots of unnecessary gear: but as a manufacturer yourself I though you would be encouraging that? You could sell them the stuff they donÃÕ need first, then sell them the stuff they do need later.

I know you are joking Tassie, but I spend a fair amount of time talking people out of inappropriate gear purchases, DSS gear included.

Divers that get what they need, and stay active in the sport will keep me in business.

Tobin

 

[Lucy's Diver]

Using a drysuit for buoyancy is not a "theory". While I do not advocate the practice some recreational agencies teach using the drysuit as primary buoyancy control.

I've never tried it with my 120's, but I have with 2 x 100's. No problem. I find it hard to believe that the ~3 additional lbs of gas in a pair of 120's is the "straw that breaks the camel's back"

If anybody doubts that your drysuit can provide sufficient buoyancy to overcome the negative buoyancy of a pair of full doubles just leave your exhaust valve closed at the surface and blow up your suit a bit at the start of your next dive. Now dump your wing and try to descend........


Tobin

Well yes, I do actually need to dump some air from my drysuit to get down. In theory, it floats me. Floating me relies wholly on the neck and wrist seals remaining sound, and it is still a huge difficult to manage air bubble. I've worked on a body recovery that was a result of someone relying on a drysuit for floatation. A breached drysuit with no futher floatation is a death trap. The wing is where it is. I'm not so worried about coming up from 80 feet, I'm worried about those moments on the surface when I may be having multiple gear failures. I want to be able to float head up in chop without a working regulator while I have to reach a tag line and pull myself to a transom. I know I can do that with an inflated wing. Relying on just a drysuit - maybe not.

 

[cool_hardware52]

First you say you suit cannot float you and your tanks

I know that my vulcanized rubber drysuit will not effectively float the full set of steel 120s I dive for my recreational dives.

Then you say it will.

Well yes, I do actually need to dump some air from my drysuit to get down. In theory, it floats me.

Which is it?

Floating me relies wholly on the neck and wrist seals remaining sound, and it is still a huge difficult to manage air bubble.

Yes, your suit would need to be in good working order.

A breached drysuit with no futher floatation is a death trap.

I agree. I encounter many diver's who are convinced that it is impossible for their drysuit to loose all of it's initial buoyancy. They are confusing the impacts of a flood with the impacts of a total failure of their suit.

That's exactly why I recommend selecting a wing with enough capacity to compensate for a total failure (can't trap gas) of the diver's drysuit.

Minimum wing capacity for doubles = Weight of back gas + Suit buoyancy + 2 ~ 3 lbs.

How many failures are you planning for? Drysuit and Wing?

Tobin

 

[Lucy's Diver]

Read carefully. I said the drysuit will not effectively float me and my rig. Do I need to dump some air when trying to descend in a controlled manner? Yes. Will it float my lifeless corpse? Yes. That is quite different than floating effectively enough on the surface to not need rescue. The seals on my suit are fine - but every drysuit diver eventually knows the feeling of too much air in the suit leaking out the neck seal. Attempting to get my head sufficiently out of the water with a full fill with the drysuit only releases air out the neck seal, creates an air bubble large enough to make the suit nearly impossible to manage, and seems just silly next to using the right piece of gear for the purpose for which it was designed.
A nearly full air bladder floats me high enough in the water to keep my face comfortably up out of the water without having to struggle. That is not possible with my drysuit.

How many gear failure scenarios do I prepare for? As many as I effectively can. Obviously, that creates some room for debate - I'm not going to sling a 40 under each arm for a no deco recreational dive just for redundancy. But given how easy a double bladder is to manage and how little extra space and gear it is it seems a no brainer.

 

[cool_hardware52]

Read carefully. I said the drysuit will not effectively float me and my rig. Do I need to dump some air when trying to descend in a controlled manner? Yes. Will it float my lifeless corpse? Yes. That is quite different than floating effectively enough on the surface to not need rescue. The seals on my suit are fine - but every drysuit diver eventually knows the feeling of too much air in the suit leaking out the neck seal. Attempting to get my head sufficiently out of the water with a full fill with the drysuit only releases air out the neck seal, creates an air bubble large enough to make the suit nearly impossible to manage, and seems just silly next to using the right piece of gear for the purpose for which it was designed.
A nearly full air bladder floats me high enough in the water to keep my face comfortably up out of the water without having to struggle. That is not possible with my drysuit.

How many gear failure scenarios do I prepare for? As many as I effectively can. Obviously, that creates some room for debate - I'm not going to sling a 40 under each arm for a no deco recreational dive just for redundancy. But given how easy a double bladder is to manage and how little extra space and gear it is it seems a no brainer.

The wing is where it is. I'm not so worried about coming up from 80 feet, I'm worried about those moments on the surface when I may be having multiple gear failures.

I want to be able to float head up in chop without a working regulator while I have to reach a tag line and pull myself to a transom. I know I can do that with an inflated wing. Relying on just a drysuit - maybe not.

Let's see if I have this scenario correct.

1) You have a full set of doubles, i.e. max negative condition.

2) Both of your regulators have failed.

3) Your wing has suffered a total failure.

4) Your drysuit seals are at least partially failing.

Tobin

 

[JeffG]

5) The borg have gone back in time and are trying to destroy the humans.

 

[Standingbear56]

If the diver is negative only by the weight of their backgas it's pretty hard to see a scenario where a drysuit cannot offset the loss of a wing. Even 2 x 130's will only hold ~20 lbs of gas.

20 lbs of displacement is a "cube" of gas about 8" on a side, not very big at all.

Why dive over weighted?

Tobin

Hi Tobin,
They are overweighted because in addition to back gas and deco bottles, they generally carry an assortment of tools to pry, chisle, saw, and/or cut away "treasure" This adds a lot of weight, and can easily overwhelm using just a drysuit for buoyancy. I tried this configuraton in the pool just to see what it was like, and my OSSystems SARR could NOT get me neutral without putting so much gas into it that I could not swim properly. If I want vertical, the gas burped past my neck seal and I was negative again. Not the way I would want to dive inside a wreck if I could at all help it. Can these added items be dumped if needed - of course. However with a B/U bladder, dumping becomes a last resort.
Again, I know this is against all DIR policies, and I know it's not the way you configure people, (I have absolutely no issues what so ever with your knowledge of the systems and the best way to utilize them - in fact, I've learned alot from reading your posts) but many divers do indeed dive this way. In fact DSAT recommends a dual bladder if not using a dry suit for it's tech courses. They specifically address this issue in fact.
Hard core wreck diving + a major training agency recommending one = a market for dual bladder wings. In fact, most of our tech bladder orders here in the US as well as overseas are for dual bladder units by a margin of 2:1.
I know dual bladders will probably never find favor here on scubaboard, and for many good reasons. Still there is a substantial market for them.
Take care,
George

 

[Lucy's Diver]

Let's see if I have this scenario correct.

1) You have a full set of doubles, i.e. max negative condition.

2) Both of your regulators have failed.

3) Your wing has suffered a total failure.

4) Your drysuit seals are at least partially failing.

Tobin

No exactly.

1) Full set of doubles - max negative (together with a can light, jersey line, primary reel, thumb reel, backup light - yes I could ditch all that, but why bother if I don't need to?).

2) Drysuit seals work as designed - keeping enough air in to keep me warm, not to float all my gear - i.e. they leak when pushed beyond design parameters.

3) Some portion of the wing fails - for example, the elbow/power inflator hose pulling out of the wing. This is more common than most people think.

Now - regulators working or not - the best I can do is float semi submerged on the surface with the suit full enough that it hampers swimming. This might be fine for calm flat seas, a quarry, or the exit of a cave. I don't dive in those places. Now add a failed regulator or even a few seconds of trying to recover a good one that somehow escaped my grasp - pretty bad scenario.

Unlikely? Sure.

Balanced against the absolute minimal extra gear and training that a dual bladder adds it is, again, a no brainer. I've never needed the airbag in my car either, it adds safety with no real down side. The second bladder adds safety with no real down side.