How much BC lift do I require?

[Wijbrandus]

Ok. So by that math, assuming I'm not taking a camera or reel, and diving a drysuit, a 30 # wing would provide enough lift? Drysuits (trilam) are neutral, except for the air you pump in to kill the squeeze, right?

Interesting. I would have assumed more. Glad I asked. Thanks.

 

[WreckWriter]

Ok. So by that math, assuming I'm not taking a camera or reel, and diving a drysuit, a 30 # wing would provide enough lift? Drysuits (trilam) are neutral, except for the air you pump in to kill the squeeze, right?

Interesting. I would have assumed more. Glad I asked. Thanks.

Drysuits might be neutral if you had nothing on underneath but in cold water that won't be the case. Start by assuming suit buoyancy about the same as a 7mm wetsuit and you'll get in the ballpark.

WW

 

[ScubaRon]

WW is absolutely right. A (trilam) drysuit may be neutrally buoyant by itself, but all the air trapped underneath can add significantly to your buoyancy.

Also be aware that there are major differences in wetsuit buoyancies depending on the type and size of wetsuit. A big and tall person in a 7 mm 2-piece can easily have 3 times more wetsuit buoyancy than a short and skinny person in a 7 mm jumpsuit.

 

[IndigoBlue]

How do you figure out how much lift you should have?

So far, I'm a warm water diver. But, living in Colorado means cold water if I want to dive locally. I'm getting my AOW this spring, and fully intend to jump into cold water starting soon afterwards once the ice breaks.

For single-tank diving (just AL80 for now), how much lift would be needed for cold water? How does one figure it? Does it change much when I move to a steel HP tank?

The reason I'm asking is I'm preparing to purchase my own bp/w before my AOW class starts, and I don't want to spend the money on the wrong wing.

Seems to me that the 30# size would be appropriate, but is that suitable for drysuit diving in cold mountain lakes?

Thanks!

This question comes up a lot, and there seem to be numerous answers.

My own answer is this. Your B/C should be able to float, with your tank and all of your weights and gear (lights, camera etc) attached to it. Short and sweet. That's my advice.

 

[ScubaRon]

Can you explain that IMO very strange advice?

 

[pipedope]

The BC is there to compensate for the change in bouyance you experience during the dive.

Air in the tanks and suit compression are the main factors.

The BC is not a life preserver (PFD) nor is it a surface float.
We generally do use it as a short term surface float but that is not its main job.

Bottom line, 30-40 lbs of lift is plenty for the vast majority of sport divers in the vast majority of conditions.

BTW If you are picking things up from the bottom, use a lift bag. Using a BC as a lift bag is dangerous.

 

[IndigoBlue]

...Bottom line, 30-40 lbs of lift is plenty for the vast majority of sport divers in the vast majority of conditions.

...

Recalling Ken's General Rule of General Rules (from another board), I am reminded that no general rule is generally applicable all of the time.

Depending on where you dive, a 10 lb lift capacity B/C could be a'plenty.

Depending on your physiology, and at a different location, 45 lbs may not be enough.

Therefore I believe that it all depends ... a concept brought home to me by Ken himself on the other board!

 

[IndigoBlue]

Can you explain that IMO very strange advice?

ScubaRon, you are a certified diver, and as such, you had to suffer through about 15 academic hours of classwork and at least 20 hours of water training. Your C-card entitles you to air fills and gear rentals and passage on dive boats.

You are perfectly free to configure yourself anyway you want.

Next time you are swimming around at 100 ft (the NACD MOD for NDL diving) in your thick wetsuit or drysuit, and for some unexpected reason you must rely on your B/C entirely to get you back to the surface (flooded drysuit, leg cramp, strong current, etc), I certainly hope your B/C can lift your full tank and all of your weights back to the surface.

You could always in a pinch EBA. But that is not recommended as a standard Plan A.

It is your choice, always. That is what your C-card means, bottom line.

 

[ScubaRon]

...Next time you are swimming around at 100 ft (the NACD MOD for NDL diving) in your thick wetsuit or drysuit, and for some unexpected reason you must rely on your B/C entirely to get you back to the surface (flooded drysuit, leg cramp, strong current, etc), I certainly hope your B/C can lift your full tank and all of your weights back to the surface.

I am quite certain I have plenty of lift, which is why I calculated it in the first place. However if I were to follow your earlier advice I should be able to get away with about 3 lbs of lift on my tropical dives. I don't think I will try that...

 

[tonaskai]

How important is BC lift for a rec. diver?