My SAC is insanely high. I warn people beforehand but I still feel bad.
Average depth of 25' I can do close to an hour on an AL80. My SAC is around 0.8cfm and my buddies have ranged between 0.35 and 0.7.
I also own small tanks, mostly 72s but a few 80s. Around here, tanks 100cf+ aren't uncommon. I ended up with some creative solutions, including doubling up my 72s or carrying an additional stage, all of which were complete overkill for the situation. I discovered that in a wetsuit, I didn't really want to do a dive longer than an hour in 50F water, and neither did my buddies.
It's worth mentioning a few things about the 72s though. One is that theyre often out of + rating, and so only get filled to 2250psi or 65cf. The next is that, due to the lower service pressure, if you leave a 500psi reserve*, you only have 78% of your tank to use, as opposed to the 83% in an AL80 or 86% of an HP100. This means that, if everyone plans to surface with 500psi, the guy with the LP72 has 50cf, the AL80 has 65cf and the HP100 has 85cf. It's not way different, but it is something to realize.
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