ronbeau
Contributor
you have to use the rated tank volume...an AL80 @ 3000psi is not really 80cf, it's 78.8cf
Not to be picky but it is actually 77.4 CF
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you have to use the rated tank volume...an AL80 @ 3000psi is not really 80cf, it's 78.8cf
What happens if you hit deco obligation on a dive that you share air on the exit?....Takes over 2/3 to get you out AND do deco. Other factors play a role too that I'm not thinking of, I'm sure.
Not to be picky but it is actually 77.4 CF
What happens if you hit deco obligation on a dive that you share air on the exit?....Takes over 2/3 to get you out AND do deco. Other factors play a role too that I'm not thinking of, I'm sure.
you blow off the stop and call your friend 'DAN' to come pick you up...
... while sharing air with your buddy.Always have enough gas to make it back to the surface, .....
Rule of 1/3 is used when you HAVE to come back to the point of origin, like a hard overhead; caves, wrecks.
In the ocean you can always go up to the surface so you do not have to use rule of 1/3 if you do not have to. You could use 1/2 if it would be NICE to come back to the point of entry. Or just a set margin (like Rock bottom) to ensure you and a buddy get up to the surface.
Now, in the ocean you can also have virtual overheads and you adjust gas requirements to that. The OP is a new diver and as such we can safely assume he/she is not doing deco/nitrox diving.
Too often you see divers use these gas rules without it being needed for the dive.
Always have enough gas to make it back to the surface, but try to do that with gas planning and thinking about it. Blindly applying ' gas rules' could end you up with not enough gas. You should never hit a deco obligation by accident. If you do, you are cutting things too close.
I think OP is on the right path by thinking about the gas needs. I just do not see why 1/3 is needed to go up........
Why in the world would you blow off a stop and risk getting bent so you could surface with air in your tank? 100ft for 28 mins is a deco dive, and could be done on a 100 but not with a practical margin of safety. Using the OP's consumption rate, this dive needs about 80cu/ft to complete, if nothing went wrong and tables were followed.
Safe Dives
Charlie