f02 formula for given ATA

[tbone1004]

Again, I only use them as vague guidelines and sanity checks and not to actually guide my dive. If my PDC is telling me that I can do 90 minutes at 100 ft on 32, then I know something, somewhere is 'off'.

I use it as my backup in the event of a failed computer since I don't carry a backup computer. I have a watch, and keep track of time. Depth is taken care of by dive planning and deco stops by either a hang line if it's there, or a DSMB with knotted line. No need to have analog depth gauge, redundant bottom time, etc for open water diving, especially NDL diving