shakeybrainsurgeon:...
And does everyone agree with Mike's belief that we should not exhaust our bcs fully when submerging. Isn't that what we're taught, or am I mistaken? First, this seems unreasonable for new divers to accomplish. Second, the PADI definition of a proper buoyancy is that the diver, with an exhausted bc, should float at eye level with a lungful of air and descend SLOWLY with exhalation. ...
You shouldn't need to fully exhaust, though a full dump likewise shouldn't send you flying down if your weighting is correct. However, "correct" can, and indeed may well, vary for people learning.
I could be wrong, but proper weighting is to hit that neutral point ("should float at eye level..."), then add the weight to compensate for tank air. If you are diving an AL80, get neutral on a full tank (3000 psi), then you add either 5 or 6 pounds. (5 pounds to be neutral at 500 psi, or 6 to be neutral at an empty tank -- I prefer the latter, will gladly trade 1 pound of "over weight" for the ability to control at the end if it hits the fan and I need to suck a tank all the way down).
The above is "ideal world". At least in my case, and many of the people I have seen, our form was pretty poor early on, unconscious body tension, we needed extra weight due to the stuff that shakes out over the first handful of dives. I ran 18 - 20 pounds with a 5mm in the pool during initial pool sessions. I dropped to 12 over my first 10 dives, can do 10 lb if I feel like it, though honestly prefer a few spare pounds (to help others now).
So, early on I might indeed have gotten pretty negative if my body was calmed down and I did a full dump.
