DUI Delta Wing BC

[tomgrogan]

I am a nitrox diver with an advanced open water certificate. I received a DUI Delta Wing BC (58lbs. of lift) as a birthday gift. I am 6' tall and weigh 218. I used a jacket BC w/ 32 lbs. of weight prior to receiving the Delta BC and my buoyancy was good to very good. I usually dive at the 40 to 60' level. I recently dove the DUI w/ 32 lbs. and an aluminum 80 tank. I found that I had to expel all the air in the BC whenever I was at 20' or less and arch my back to keep buoyancy. I put on 4 lbs. of tank weight (still 32 lbs. total) during the next dive but found it didn't help much except that I was a little more vertical at the surface. I do plan to go to the pool for a buoyancy test but wondered if someone could answer a few questions: 1) Is 58lbs. of lift exessive for someone my weight; 2) Is it reasonable to put on more tank weight than 4 lbs.; 3) Is a crotch strap a good alternative to keep a BC from riding up once depth and wet suit compression is achieved rather than tightening the waist belt at depth; and 4) I know it varies but just what is a reasonable range for weights for someone my weight.
I would very much appreciate an experienced diver or instructor's opinions on these questions

 

[theskull]

I like this question, contains a number of issues.
Changing the position of the weights without adding to the quantity will not help you stay down if you are floaty at 20 ft. Add another 2 lbs.
1. Some of the minimalist crowd will say that 58 lbs. buoyancy is excessive, but I strongly prefer having lots of lift. You only use what you need, and have plenty left over in case you need to help a negatively buoyant buddy or (gasp) retrieve a small anchor.
2. I have dived with as much as 10 lbs. tank weight. Move your weights around and find where they are right for YOU with YOUR gear on.
3. A crotch strap is comfortable for some and not for others. Best solution is to dive in a horizontal postition and put more weight on your BC and tank rather than on your body to keep the BC from riding up.
4. You need to wear as much weight as you need to wear. No good or bad, just necessary. You may need a bit less as you get more experienced and relaxed and learn better breath control.

Have fun and dive safe,

theskull

 

[cummings66]

One possibility is your BC is trapping air in some of the folds causing you to have air in it when you think it's empty. I've got a buddy who dives a BC with a bit more lift than yours and his will sometimes trap air causing him to have buoyancy control issues.

With time and diving you'll learn it's quirks and probably be fine at your old weighting, in the meantime I'd do as theskull suggested and add a couple lbs.

As to what's normal, wow, that ones been asked so many times before that I can tell you the answer is....

42

I can't help it, I like books. Really it varies all across the board. No right or wrong, it is what it is. Next time your down to 500 psi or close do a check before getting out of the water. Takes seconds and it's going to be pretty close to right on. Probably closer than a pool check because you'll be more relaxed where you might be tense in a pool. That's really the secret, be completely relaxed when you do the check.

 

[cummings66]

I forgot to add, when I dove a traditional jacket BC I had to put half of my weight on the tank up high, the other half in the upper trim pockets. I had in a 7mm wetsuit a need for 16 lbs of lead and could not place it on a belt or in the weight pockets because I'd be diving standing up. To acheive horizontal trim it had to be up high.

At the time I was 6' 180 lbs, about the same now. I've got buddies close to your weight and some of them use as much weight as you do, and some use less.

Crotch straps work for me.

 

[tomgrogan]

Thank you The Skull & Cummings66 for your answers. Coincidentally, I went to the dive shop that sold the BC & was able to talk to a seasoned instructor/franchisee that provided some interesting answers to my questions. I thought that I would share them w/ you: 1) The instructor suggested that I dive with a steel rather than an aluminum tank w/ the advantage being that I would need less weights because of the negative buoyancy of the tank coupled with the 58 lb. capacity of the BC at surface; 2) The instructor also advised that the addition of a crotch strap was not a factor in obtaining proper buoyancy; 3) Proper fit of the BC definitely affects the amount of weights needed as the common error is to add weights rather than adjust fit/trim; and 4) Most importantly - The DUI BC intake/exhaust valve should be kept facing down with the left shoulder lifted when descending. This will expel the air in the BC at the needed rate to controll ascents and descents. Finally, I will have a pool session with the instructor who said that he thought with all of the above utilized that he would drop my weight usage by a significant amount. Thanks again for your inputs!

 

[cummings66]

4) Most importantly - The DUI BC intake/exhaust valve should be kept facing down with the left shoulder lifted when descending. This will expel the air in the BC at the needed rate to controll ascents and descents. Finally, I will have a pool session with the instructor

Two things, first I suspect you meant "lifted when ascending" not descending and the pool sessions not a bad idea.

The reason I say ascending is because on descent you'll be adding air not removing it and so the position of the exhaust valve won't really matter at that point other than having it handy.

A pool session is always a good idea prior to diving with new gear, sometimes there are quirks to work out or plain getting familiar with it in the first place. I've seen horror stories happen due to lack of familiarity.

 

[Goose75]

I’m a hair under 6ft and weigh about 195lbs. I also have a delta with the 58# bladder.

Here are my thoughts on your questions.
1) The only regret I have is that it has a lot more drag than other back inflate BCs I tried later. Here in Texas many people tell me it’s excessive. When I bought it in Seattle, I was encouraged to take the attitude more is better. I’ve used it all over, it works but I’ve never had to fill it enough to use the excess. I probably wouldn’t buy it again but it’s done the job.
2) I used to throw 3lbs on the tank for trim but I don’t very often anymore. I roll on my back on the surface now so I don’t find the need for the “trim” anymore. I do notice that the bladder makes it hard to float on your back if it has much air. I tend to fill it and bleed out as much as I need to be comfortable if I’m floating topside for a while.
3) The weight belt is almost always loose fitting on me. I’ve tried to readjust to get it tighter with some success but not much. I leave the crotch strap a little loose on entry so it doesn’t irritate and then tighten it up in the water.
4) Personally I have dove with a shorty, 8lbs weight and an Alum 80. It was warm fresh water and it was cutting it too close but it worked. I was experimenting with how little I could dive with. In Seattle I dove with 30lbs in it a few times when learning to dive with a dry suit. I was a new diver and carried a lot more weight than I do now. If you want to dive with less weight, there are lots of good threads on it, or PM me and I’ll ask you a bunch of questions to help you figure it out. Salinity, the amount of neoprene, your amount of activity and a bunch of factors will make every case a little different.

Once I learned how little I could dive with, I added back weight. Too much weight is no fun on the back but too little isn’t a good thing either.

I won't be logging in Fri-Sun so I may be so to respond if you PM.

 

[tomgrogan]

You are right Cummings66! Thanks for pointing out that I did mean lift while ascending
in my answer. Quite frankly, I had an immediate opportunity to do a fresh water dive when I got the BC. I got excited to use it rather than first doing a pool check. I have learned from that mistake even though I knew beforehand there could be consequences. Patience is a virtue!

 

[tomgrogan]

Goose, when I talked to the instructor I also asked him if 58 lbs. of lift was excessive for a BC. Basically, he said " not necessarilly as you don't have to use the full lift capacity unless you want to float high on the surface w/ heavy a heavy tank, weight belt, ect." He added " most of the time the BC only requires 1/2 inflation but of course that fluctuates depending on the diver." Regarding your answer number 2 & 3: look at my 4/4 post to Skull & Cummings66 based on questions I asked the instructor. Thanks for your reply as it helped me to know that others using the DUI had similar problems that can be worked out with more experience.

 

[MSilvia]

It sounds like your instructor has some good advice. Listen to him, and let us know how the pool session goes. As for the "Is it excessive for my weight?" question, I don't see what your weight has to do with it. If you are weighted so that you are neutrally buoyant, your effective weight underwater is zero. It's a matter of how much buoyant capacity you need in addition to that, not how much you need to counter your dry weight. If you expect to encounter a situation that makes you 58 lbs negative, then you need at least 58 lbs of lift to counteract that. Personally, I only dive with a 40 lb wing when diving with double HP100 steel tanks that are extremely heavy on land, and I weigh 265. I have a drysuit for backup buoyancy, but I've never had to use it in that capacity.

One other thing... if you ever have an anchor you want to lift, you'll be much safer doing it with a lift bag/SMB than by adding buoyancy to your BC.

Suppose you found a 20 lb anchor at 70 feet. If you added 20 pounds of lift to get it to the surface, and then accidentally let go of the anchor, would you rather that 20 pounds of lift was in a bag keeping the anchor neutrally buoyant, or that that 20 lbs of lift was in your BC, leaving you 20 lbs buoyant and ascending rapidly?