You're all speaking of 30lbs extreme maximum for single tank wing and I'm here considering a 42lbs wing (xdeep NX zen) for single tank 7mm wetsuit. Should I be worried ?
Typhon,
What I have always recommended WRT to required lift is:
1) Any BC needs to offer lift greater than the maximum negative buoyancy of your "rig" . For a BP&W that will be the plate, harness, reg(s), Full Cylinder(s) tank bands and manifold (for doubles), can light + any ballast attached to the rig.
For the typical single rig with a Stainless Plate, and full ~HP 100 steel tank this will be about -18 lbs.
If your wing is smaller than 18 lbs you run the risk of losing your gear if you have to ditch it.
2) Offer lift greater than the maximum possible change in buoyancy of your exposure suit. This allows you to compensate for a fully compressed wetsuit, or the total failure of a drysuit.
In cold water it's almost always the buoyancy of the diver's suit that determines the minimum safe wing capacity, and in warm water it's almost always being able to float the rig.
If one is only diving cold water it matter's little if you oversize the wing a bit. The difference in drag, stability and ease of venting between a 30 and 35 is trivial.
Where it matters is when a diver is trying to use one wing for warm and cold. Careful selection of the cold water wing, i.e. not larger than actually needed, often leaves the diver with a wing that is reasonable to use in warm water too.
In 99% of the cases I've dealt with, which in many many thousands, the key piece of intel is the buoyancy of the cold water suit. Maybe 5 in 100 divers actually know how buoyant their exposure suit is.
How buoyant is your suit? Is it anywhere near 44 lbs? I doubt. Most wetsuits, even 7mm farmer johns are under 30 lbs, and very few drysuits are over 35........
Tobin