Originally Posted by Tosh Togo
You need to rethink that concept.
The drop in the net weight of a C/F tank versus the same capacity aluminium one will be far less than the reduction in bulk is, so the net buoyancy will be greater, not less.
It's the same mass of air in both tanks...
Speaking of SCUBA tanks, back in the 60's I watched one at the KMCAS dive shack hit the deck the wrong way, just after being filled... it was a short-impulse JATO, and skipped a few times before it finally was grabbed by the water.
The valve took a while to find...
I understand the concept, I should have worded it differently. The increase in weight needed will be offset somewhat for a CF tank due to the smaller size then if it were a CF tank that was the same size as a standard AL80. That is for a tank of similar capacity, 80ci at the rated psi. The other trade is a tank of the same size as an AL80 will likely hold significantly more air.
Still a better tank, lighter, more streamlined, better capacity, less corrosion concern etc. I bet the overall weight of a CF tank plus the weight needed to sink it will still be less then the combined weight of an AL80 and the weight needed to stay negative/neutral by the end of a dive. AL80's are crap, they just happen to be popular crap.