Choosing a BC with enough lift capacity

[eelnoraa]

44lb is a lot of lift for single tank diving. Do a properly weight check and see if you really need that kind of lift.

Not an expert, but here is what I learned from this board, and 45 minutes phone conversation with Tobin of DSS. You BC lift should determine by 2 things:

1. float your rig by itself with tank full, so if you ditch your entire rig, it should float at the surface if BC is fully infated. If you have all your weight integrated, you will need more lift. Otherwise, it is just tank, BC itself, reg, lights, camera.....

2. it should compensate the bouyency lost due to wetsuit compression.

Actually, I think 22lb (10% of your weight) is not too bad if you use a conventional BC (not BP/W). If all your weights are integrated (-22), you use HP120 (-11), reg (~-2), light(~-2), camera (~-2). These are -40lb total. I highly doubt any 7mm wetsuit out there has -44lb to lose. So 44lb of lift should be plenty. If you are willing to move some of the weight to waist, you can further reduce the lift capacity.

 

[aaronp]

As others have said, you can get a 65lb bladder for the Zeagle Ranger. The Zeagle Tech comes standard with the 65lb bladder BTW.

44lbs may be a lot of lift to you guys, but for some it might not be enough.

He's diving in cold water, if he's diving in a wetsuit, he's probably got two layers of 7mm over his torso (farmer john). He's gonna have a nice thick hood. Nice thick gloves.
He said he weighs 220 lbs, which means he's a fairly big guy. The more water you displace, the more bouyant you're gonna be. Now add a couple of extra yards of neoprene to cover that extra "big guy" stuff (times 2 over the torso) and you are talking about a significant amount of extra lead to sink.
The bigger you are, the more lung space you have too. This causes you to be more bouyant. (and suck more air :depressed: )
Being a new diver, he's gonna have an AL80 (not a HP120!) which is 4.5 lbs bouyant when empty.

I'd guess that as you get bigger, your weight belt gets heavier exponentially, not linearly.

I'm 6'5" and in some situations (like diving in a wetsuit), 40lbs of lead just barely sinks me. Switching to a drysuit has helped a lot, but if you have enough insulation under the drysuit, it's almost as bad.

So, just because YOU don't need 44lbs lift, doesn't mean everyone doesn't need it. One size does NOT fit all.
If nobody needs 65lb bladders, why do they make them?

 

[GrumpyOldGuy]

As others have said, you can get a 65lb bladder for the Zeagle Ranger. The Zeagle Tech comes standard with the 65lb bladder BTW.

44lbs may be a lot of lift to you guys, but for some it might not be enough.

He's diving in cold water, if he's diving in a wetsuit, he's probably got two layers of 7mm over his torso (farmer john). He's gonna have a nice thick hood. Nice thick gloves.
He said he weighs 220 lbs, which means he's a fairly big guy. The more water you displace, the more bouyant you're gonna be. Now add a couple of extra yards of neoprene to cover that extra "big guy" stuff (times 2 over the torso) and you are talking about a significant amount of extra lead to sink.
The bigger you are, the more lung space you have too. This causes you to be more bouyant. (and suck more air :depressed: )
Being a new diver, he's gonna have an AL80 (not a HP120!) which is 4.5 lbs bouyant when empty.

I'd guess that as you get bigger, your weight belt gets heavier exponentially, not linearly.

I'm 6'5" and in some situations (like diving in a wetsuit), 40lbs of lead just barely sinks me. Switching to a drysuit has helped a lot, but if you have enough insulation under the drysuit, it's almost as bad.

So, just because YOU don't need 44lbs lift, doesn't mean everyone doesn't need it. One size does NOT fit all.
If nobody needs 65lb bladders, why do they make them?

You are mostly talking about weighting issues, not LIFT issues!

 

[crandf]

IMHO, I think you are carrying too much weight. Your weights should be enough to maintain only slight negative buoyancy when your tank is nearly empty and BC fully deflated. So if you use just enough lead weights that you can maintain your safety stop with your BCD is only slightly inflated even when your air is down to 10 bar, then your total buoyancy can probably be pushed to positive by even a BCD with only 20-30lbs lift.

FYI, I perform my safety stop with no floatiness with minimal air in my wing when my air is down to 10bar, and when I come up, even just inflating my 30lb wing about halfway is more than enough to keep me comfortably afloat.

 

[Mike Boswell]

As has already been mentioned, in most cases for single tank diving, 44 lbs. of lift is waaaay more than enough.
I have a 30 lb. lift wing for my single tank drysuit diving. If I wanted to, I could probably go down to a 26 lb. lift wing.

FYI, lift capacity is not determined by how big you are or how much you weigh. It has to do with the buoyancy of your exposure protection, the kind of tank you're using, and how your ballast is distributed (on the diver vs. on the rig).

The wing needs to do the greater of: (a) able to float the rig at the surface (without you in it) or (b) able to compensate for maximal loss of buoyancy of your exposure protection at depth.

Based on these criteria, 44 lbs. of lift is probably overkill for most people. For instructors and DMs who might carry some extra weight to give to a student/customer who is under-weighted, it might make more sense to have a BCD with a little more lift than necessary.

In case of emergencies, like performing in-water rescue breaths, it won't hurt to have some additional buoyancy. A larger wing - say a 40# versus a 30# - does not cost more or present significantly more drag, but could make a big difference in some situations.