How to calculate appropriate wing size?

[HullBlister]

In a way, this is sort of a sanity check in addition to information gathering....

Someone, sometime, once told me (doesn't all good SCUBA lore start out that way?) that when selecting the proper wing for a BP/W set up that the wing should be have enough lift to float your rig without you in it @ 85% capacity.

That said...

SS BP = 5.5 lbs
HOG Rig = 1.75 lbs
Single tank adapter = 1.5 lbs
Cam bands = 2 lbs
Full AL80 (in water) 1.4 lbs

Total = 12.15 lbs

This then would suggest that even a 17lb lift wing would be fine since 85% of 17 lbs is 14.45 lbs.

Does this make sense?

Thanks!

Blister

[String]

That doesnt take into account displacement.

Anyway, its simpler than that. Assuming the diver is *properly* weighted the wing needs to be able to list the weight of the gas that will be used during the dive and no more than that. For a typical 12l tank thats about 3kg (7lbs) of gas.

Then double that figure to give you some surface buoyancy. So about 14lbs in the case of above.

You only have to start looking at other stuff if the diver isnt wearing any weights and is still negative to start the dive (big twinsets and stages etc).

[Scared Silly]

Never heard the 85% rule. Remove that and you have the first of what Tobin says.

[bryanmc57]

Here's Tobin's formula...

The Deco Stop (http://thedecostop.com/forums/showthread.php?t=32358)

[HullBlister]

Thanks for the replies!

Blister