I've read up on boyancy and am still unclear if I'm missing something. It seems that a 30# wing is fine for single tank dives. Is the only way to figure it out to get into 10 feet of water and neutralize w/ empty bladder and add 9lbs suit compression and 6lbs air loss...as they say on the halcyon site. Is the kicker If you use steel vs Alum tanks?
TT
Wing capacity is mostly a function of the buoyancy of your exposure suit. You have provided no information about your configuration.
The reason why divers need
Buoyancy
Compensators is their exposure suits loose buoyancy as they descend.
If you jump in the water in your swim trunks there's no neoprene to compress. If you jump in the water in a full 7mm suit with hooded vest there may be 25+ lbs worth of buoyancy to be lost as the diver goes deeper.
The ultimate goal is to be weighted so your total ballast is equal the buoyancy of your exposure suit at your shallow stop depth with a (near) empty tank.
If your back plate + harness + regulator + empty tank is less than this minimum required ballast add a weight belt.
If your back plate + harness + regulator + empty tank is more than this minimum you need to change to a less negative tank, or less negative back plate.
**The solution to being over weighted is not a larger wing**
You have provided no suit info or tank info so the best I can do is provide an example.
If you are diving locally I'll assume cold water (7mm wetsuit) and steel tanks.
Any "personal buoyancy" will impact your total weighting, but will not require compensation, fat doesn't compress at depth.
A medium SS plate and harness is about -6 lbs, a reg is -2 and a full HP 100 is about -10. That makes your "rig" about -18 lbs with a full tank, and about -10 with an empty tank.
If your 7mm suit is + 26 lbs you will need about 26 -10 (ballast of rig) = 16 lbs additional ballast. I'll assume you choose to add 8 lbs of this 16 to your rig via bolt on weights or pouches etc.
Now your rig is 18 + 8 = 26 lbs negative with a full tank, and provides about 18 lbs of ballast with an empty tank. 26 -18 = 8 lbs in a belt.
To float this rig, even with a steel tank and extra bolt on ballast you need a wing that is greater than 26 lbs.
Your wetsuit cannot loose more buoyancy than it starts with and I've **Assumed** it was +26. You need a greater than 26 to be able to compensate for a fully compressed wetsuit.
30 > 26. A 30 lbs wing would be fine. It is a rare wetsuit that is more than 30 lbs positive, and it is a rare single tank rig that will be more than 30 lbs negative.
Tobin