Posted by Bill Johnson on December 01, 2001 at 07:26:40:
In Reply to: Re: Timewise - actually could be 20% less posted by Ken Kurtis on November 30, 2001 at 00:51:26:
Ken,
I don't think 20% less bottom time is accurate.
First, aluminum 80s don't necessarily hold 80cf of gas. For example, a Luxfer holds 77.7cf. So by your calculation, 65.1 / 77.7 = 16% less GAS.
Second, I would argue that since the cylinder itself weighs less and has better buoyancy characteristics than the 80 (allowing less required ballast weight), both of which result in less total diver mass, the 72 could result in better gas consumption. These gas savings would come from less effort required to get less mass moving and from less drag from the BCD which would be less inflated with the 72.
I think it is possible to get close to the same bottom time with a 72 as with an 80.
Regards,
Bill