What's your TBT on a AL80?

[elan]

at 33' about 160 minutes.

My SAC is .4 in open water.

To get 160 mins you need to have a sc of .24 full fill and suck it all dry Unless you mean 33' above the surface

 

[Rascally Rabbit]

There are a number of factors that effect SAC rates. We are all aware of conditioning, exertion and depth has a major effect but other things such as how finely tuned your trim and buoyancy is. How streamlined you and your gear are. How consistant your depth is without the need to add or remove gas from your BCD. How relaxed you are in the water. How cold or warm you are and the level of protection, fit and ease of movement your exposure protection gives you. Then after all the other details are taken care of the question of whether the environmental issues such a current, surge and temperature decides to work with or against you on any given dive. If you've done as much as you can with all these issues and your dives are still cut short by your supply of air simply invest in larger tanks and stop worrying about SAC rates.

 

[jupitermermaid]

I agree. Usually I have to ascend because of time factors rather than PSI. We are allowed 45 minutes bottom time at 60-90' each dive, which I'll normally come up with 1300-1600 PSI on a steel 80. Haven't used AL in quite a while, so don't know what PSI would be left after 45 min. bottom time. At BHB, I can get a good 90 min. with lots of air left over after the dive. The determining time factor is the tide and/or other people diving at the time.