Wing or BC lift capacity calc's

[cool_hardware52]

Hi folks. I new here and new to forums in general so I hope understand enough to post this question. If I'm violating any protocols please let me know.

That said I'll admit to lurking for a while. Seem to be considerable debate about what wing to use with what set up. how much lift is needed etc.

My question: Is there any recommendations / standards etc regarding required or recommended lift that one can refer me to?

It seems to me, and perhaps I'm missing something, that the minimum lift is equal to the maximum loss of buoyancy due to pressure. In other words if a diver is neutral at the surface with no air in the BC, or minimum air in a Dry suit the max buoyancy he can "loose" is the compression of his wetsuit or loss of the lift in dry suit if it flooded.

Given that most wetsuits, even thick XL sized suits, provide maybe 30-35lbs of floatation, and this is the max lbs that can be lost through compression of the material what configurations demand 70, 80 or 100 lbs lift wings?

An inquiring mind awaits your collective wisdom.


cool_hardware52

[jonnythan]

To figure out how much lift you need, figure out your maximum negative buoyancy for the dive. For instance, if I'm diving a 3mm wetsuit with an Al 80, then I can potentially be up to 15 or so pounds negative (~ 6 pounds of gas, 9 pounds of wetsuit buoyancy lost), assuming I'm properly weighted. So, the max flotation I'd need for that dive is 15 pounds, plus a couple for a safety margin.

If I have a drysuit with a steel 100 cf tank, then I may need more. More gas (8-9 lb), and a flooded drysuit could make me several pounds more negative.

Another consideration is floating your rig by itself. My backplate, STA, channel weight, and full Al 80 tank are about 20 pounds negative on the surface. Therefore I'd want at least 20 pounds to make sure it doesn't sink if I take it off.

As for the 100 pound wings, that should virtually never be needed. If you were carrying a lot of gas in very heavy, negatively buoyant steel tanks - 2 on your back, 2 more slung on your side - coupled with a thick wetsuit or neoprene drysuit that loses its buoyancy at depth, you could potentially be that negative. 30 pounds of gas, 30 pounds of suit compression.. you get the idea.

[cool_hardware52]

Thanks Jon, I had not considered the obvious benefits of being able to keep the rig at the surface if I ditched it.

Even so it seems some what odd that so many hugh wings are for sale. I see 60-70-85-90 and 100's!

Seems a big floppy wing kinda cancels the benefits of the clean streamlined BP & wing.

Is it simply a case of "My bigger wing is bigger than your wing?

Thanks again

C_H

[jonnythan]

The wings in the 50-100 pound rage are intended for double tanks, not singles. They fit nicely with a set of doubles - look at the top pic at http://halcyon.net/mc/explorer.shtml

Some people use such wings on their single tanks simply because they don't know any better. Some people diving doubles use the biggest wing they can find, "just in case they need it."

[bcsean]

the halcyon explorer 55 is a very common wing for twins. There are very few instances that anyone will need more then that.

[d33ps1x]

Thanks Jon, I had not considered the obvious benefits of being able to keep the rig at the surface if I ditched it.

Even so it seems some what odd that so many hugh wings are for sale. I see 60-70-85-90 and 100's!

Seems a big floppy wing kinda cancels the benefits of the clean streamlined BP & wing.

Is it simply a case of "My bigger wing is bigger than your wing?

Thanks again

C_H

Interesting that you need all these answers since in other threads you profess your own wings and bp's to be the worlds best.

How would you know based on your obvious lack of knowledge about the things?...