Reduntant cell or not!

[leadweight]

Worried about extra $$$? Compared to the big picture, the cost of a dual bladder wing is not that much more.

 

[ScubaDadMiami]

I have an OMS dual bladder 85 pound lift set of wings with plastic Dive Rite backplate that has been sitting around here just waiting for me to get rid of them. If that is the route you decide to go, I have a nice set that is looking for a good home.

I became a conformist and went to single bladder and aluminum backplate.

 

[wedivebc]

I've got a dual bladder dive rite super wings for sale. I bought a BP/w rec wings 55# and I find I was able to remove several # from my harness. If you are properly weighted it should not matter what type of tanks you are using (assume you are using weights) because you can eliminate the lead until you are neutral with near empty tanks so your bouyancy system only need s to lift the weight of the gas in the tanks at the beginning of the dive (about 10#).
So why use redundant cell? If your drysuit can't lift 10# or so you should get a new neck seal.

 

[kramynot2000]

What I am trying to see, if there are any requirements when it comes to the technique or any training (agencies, courses) that require a certain size bladder? Any certain techniques that a large 100 bladder is a must? (ie: number of tanks, depth, situation/location, diver size)

Well, I took the DSAT TecDeep course and am now in the Tec Trimix course. The materials for this course do not mandate a dual wing but discusses the arguments for and against, similar to what's on this thread. The course requires redundancy and cautions that some drysuits will not have enough lift in case of a bladder failure. So its left up to the diver.

The courses also don't mandate a certain size bladder, just have enough lift for your gear. Personally I dive a DiveRite Superwing which I think has a 75lb lift capacity or something like that. Is it more than I need, maybe, and probably with small doubles. But I really don't feel any difference from diving with my smaller wings so I'll keep it... bungees and all! YMMV.

 

[wedivebc]

Boy this is a topic with a lot of opinions.

I think all agree on redundancy but there is disagreement on whether it should be another bladder, your drysuit, or even a liftbag.

As for me, I dive dry and use a dual bladder wing for the tech stuff. Before I bought the wing, I tried to use my drysuit for bouyancy control to bring me up from 20' with a set of steel doubles and it was extremely difficult because of all the air I had to put in the drysuit and air started burping out the neck seal. Holding deco stops would be a challenge if I had to. Another buddy of mine tried this as well at 60' and couldn't get off the bottom. There was just not enough lift before the air started burping out the neck seal and this was with steel 80's and 85's. I know there is no way I could use the drysuit for redudancy wearing my 95's and/or full deco bottles especially larger bottles like AL80s.

The theory you'll hear is that you should have a balanced rig and be able to swim up your doubles at 500 psi and also use your drysuit for emergency bouyancy. Although I've asked around, I've found very few who have actually tested this which is why I decided to try.

My recommendation is to slap those doubles on your back and go out and simulate a bladder failure. If your drysuit can lift you, great. Some people are more boyuant than others and some drysuits have more lift than others. If not, I'd look into the dual bladders.

FWIW, I've had no problems at all with the extra bladder and find its really not an issue having another inflator.

I can't believe what I'm reading here!
If you are in a drysuit it will take the same volume of air to lift you from 60 ft or 600 ft. Wetsuit is different because of neoprene compressing but not that much. If you could not get off the bottom with your drysuit then you are grossly overweighted. You should have addressed this issue on your tech course and I am really hoping you get set up properly before you attemp trimix. Do dsat courses require you to hover when doing skills or do they kneel on the bottom?

 

[kramynot2000]

I can't believe what I'm reading here!
If you are in a drysuit it will take the same volume of air to lift you from 60 ft or 600 ft. Wetsuit is different because of neoprene compressing but not that much. If you could not get off the bottom with your drysuit then you are grossly overweighted. You should have addressed this issue on your tech course and I am really hoping you get set up properly before you attemp trimix. Do dsat courses require you to hover when doing skills or do they kneel on the bottom?

Dave, I guess I wasn't clear in my post. I could get off the bottom at 20' but it was difficult because air was burping out the neck seal. I guess I could get a tighter neck seal but I've never had a leak so I don't see a need. And no, I wasn't overweighted. I never wear more than 10lbs with a set of steel doubles. On the day I was trying this out I think I only had about 8 lbs on my belt with an aluminum BP, which is my usual config for 80's.

I put on a full set of steel 80's, dropped to the bottom and simulated a wing failure. Did I come up, yes with difficulty but I lost air out my neck seal. I had to go vertical to kick off the bottom which caused my neck seal to be the highest point, allowing the air to escape. My suggestion is simply to go and test it.

And yes, in my DSAT course we had to hover and maintain neutral bouyancy when doing skills, valve drills, etc.

 

[jonnythan]

Why did you have 8 pounds on your belt if you were basically glued to the bottom with an empty BC?

 

[kramynot2000]

It was just a test to see if my drysuit could provide enough lift for my normal doubles rig. Many people say you can use your drysuit in case of a bladder failure so I wanted to check it out because I never actually met anyone who tried it.

If I dropped my belt I'm guessing would not have been a problem getting off the bottom.

 

[jonnythan]

But I'm trying to figure out why you were adding an 8 pound belt if you were already quite negative. It doesn't seem to make sense to me.

 

[wedivebc]

It was just a test to see if my drysuit could provide enough lift for my normal doubles rig. Many people say you can use your drysuit in case of a bladder failure so I wanted to check it out because I never actually met anyone who tried it.

If I dropped my belt I'm guessing would not have been a problem getting off the bottom.

I would suggest if you use less weight you could use your drysuit. If you were pinned to the bottom you can still afford to lose some.