When would you head back.......

[mjh]

While TSandM's answer is "correct" in it's way and is the safest way it is not the "absolute answer" (IMHO). Over 25yrs I have dove many times to +120 on a AL80, done all the required deco stops and still hit the boat/shore w/+700psi. So there is some flexibility dependent on your ability and air consumption.

 

[MXGratefulDiver]

While TSandM's answer is "correct" in it's way and is the safest way it is not the "absolute answer" (IMHO). Over 25yrs I have dove many times to +120 on a AL80, done all the required deco stops and still hit the boat/shore w/+700psi. So there is some flexibility dependent on your ability and air consumption.

Assuming you're either diving buddyless or that both you and your dive buddy have extremely low gas consumption ... or you don't plan to donate a reg if your buddy has a problem that causes a loss of his breathing gas ...

... Bob (Grateful Diver)