Safe tank pressure at which to begin accent.

[BRT]

diving solo changes things. If I'm diving truly solo, i.e. no one else is in the water, or I'm diving with a trusted buddy with redundant gas supply, then yes I 100% agree with your numbers and it honestly about where I would leave the bottom. Unfortunately I have been mugged on more than one occasion and because of that, I choose to leave plenty of gas in the tank because I am not risking myself by making a rapid ascent and blowing a safety stop. If you look at my original numbers of leaving the bottom at 1800 psi, and cut that in half for solo diving, I'm about where you are. My SAC rate is a bit higher around .45, and I dive with Poseidon Jetstreams so I have to be very careful about my ending pressure because they are upstream regulators and will freeflow if the IP drops much below 100psi, so my padding has a pressure minimum regardless of tank size that I choose not to violate, which is 400psi instead of 200psi, so we're actually in the same boat.

The major issue I have is the lack of time that you guys are factoring to remedy the situation and calm the OOG diver down enough to not make a super rapid ascent. That to me is very important and I plan for at least 2 minutes at depth to take of that just in case... Better to plan for the worst and hope for the best.

Oh, of note since "boat" was mentioned. If there are safety bottles on the hang line, then the gas planning changes since one of you can hop on that. In that case, that gives you an extra 300psi in an AL80

Any place I have dove off a boat I would not want to bet on finding the hang line in an OOG emergency. I'd be fine with a 60fpm ascent in an emergency and 500psi on an AL80 will last my wife and I longer than 2 minutes. I know for a fact our regulators will breath below 100 psi on the gauges. Seems silly not to check that.

 

[diver 85]

OP----in your case nice round number ??1500(if you're having to ask)----mine would be lower though.....