Apology accepted.
Well, yes, I did wonder if that was what you meant, and the reason I wondered is that I don't use my BC as an elevator, so in fact it does not do the work of taking me over obstacles or to the surface. I certainly wouldn't pump air into my BC to become positively buoyant while underwater except perhaps in the most dire emergency, and furthermore I teach my students not to use the BC to effect depth changes. For this reason, I was surprised to read your sentence, and I wondered whether I was mis-interpreting it.