I have to agree with the conservative air management statements in this thread, I understand that with many different forms of scuba, there are many different needs and safety margins. Perhaps my relatively small number of logged dives keeps me conservative, but I consider 500 psi on the surface as pretty solid low. I would use that air only if I really needed to, if I had problems, or if I needed to finish a safety stop due to poor planning. But I personally don't trust regulators and gear to function well below 500 psi. What if your guage is off? Running out of air is a critical situation at all depths. I would look at dropping below 500 psi as similar to ascending well above normal rates and running a DCI risk.
In SSI (and I find their ideas about this logical, if not written in stone) the idea is 10 psi per foot OVER your 500 psi. That means a 90 foot dive (if you went to 91 feet that would also mean you should round up to 100 feet in my personal system). So that is a turned dive at 1400 or 1500 psi. 2000 psi seems a bit conservative for open water, in my book, but again I would stress that in all my contacts with more experienced divers, and all my several years of diving research (marine biologist) I have always come away with conservative simplicity in mind. If ending a dive at 1500 psi or more, depending on depth, cuts your dive too short - bring more air. I would much rather bring more air than suck a tank lower than 500 at the end of the dive. I also consider a pony or doubles a good idea in 100+ feet, or shallower in cold water like we see up here.
As to that buddy, I dont want to beat the issue to death but I would leave right away.
The air share makes me very nervous, knowing how flaky he was. Unless you were so low that you would lose stop time (unclear if you would have at 500 psi at 45 feet), I wouldnt trust the guy with the tangled octo for my air. Also, while I stick to a 30-20-10 saftey stop system on dives below 50 feet (my little decompression schedule), I would probably go directly to 15 feet if my air was low. 5 min at 15 feet with 500 psi should be doable, but also keeping in mind I would be ready to leave if the reg started to choke up. That may mean losing my belt at that point.
Waiting longer would have been very scary indeed - if he doesnt let you end the dive when you ask, will he let you share air when asked? That is a bad question. What if he swam away suddenly as bad buddies are known to do?
We know that all too often the bad buddy is a boyfriend or husband or pal from school (why are they so seldom women?) and the poor new diver trusts them and stays with them, and then they panic and die OOA. Glad that wasnt you at all.
almtree: Bob
