Use true size of Al 80?

[craigda]

Question: Al80's are really 77CF. Should 77 be what I put in for the tank size to get a more accurate SAC?

Thanks.

[nick]

You can put whatever you like in there really - I would think that the key thing is to be consistent so that all of your dives are being compared the same way.

[craigda]

Let me put it this way: the number you put in for tank size is the number that is actually used to calculate the SAC, yes? So a more accurate size for the tank will yield a more accurate SAC. (Certainly seems that way, based on experiments fiddling with the tank size.)

To broaden the question a little bit, I assume MacDive uses the entire dive profile to arrive at the SAC, not just the max depth or something like that? (Apart from simple optimism, I say this because of the consistency in the calculated values across quite different dive profiles.)

Thanks!

[nick]

Yes, that number is used to calculate your SAC.

The average depth is used, not the max depth.

[craigda]

Thanks for your time!