Solicit simple SAC solution

[Cave Diver]

captndale has a very good point.

I just did 18 dives off Little Cayman. Using a tank volume of 80 cu ft, my SAC had a range of 0.36-0.44 and a mean and sd of 0.39 +/- 0.02 cu ft/min. Using 77.4 cu ft, my SAC had a range of 0.35-0.42 and a mean and sd of 0.38 +/- 0.02 cu ft/min.

Conclusion, under the conditions off Little Cayman, my SAC is 0.4 cu ft/min with a relatively narrow variation. It's always good to prove it to yourself. This happens to be my normal SAC in relatively warm water with little to modest exertion over the last couple years.

Good diving, Craig

Cave Diver, where is the Defender badge???

The Defender badge appears to have been a casualty of the photo attachment fix. It's being looked into and should return shortly.

Thanks for the quick response, I can see how a technical diver could benefit from that type of calculation. Especially a cave diver or anyone who enters overhead situations. Another question if I may, doesn't the sac value vary with changing depths and if so wouldn't exploring a place or area that your not totally familiar with effect the accuracy of the calculation. And forgive me but where do you usually turn a dive around to start your return to the surface and or boat. Thanks again for the information.
Bill

SAC is a constant, it's based on your surface consumption. You apply your SAC rate to the depth to give you an idea of how much gas you'll use over a given time for that depth. Typically we calculate normal SAC (leisurely dive) working SAC (high exertion/current, etc.) deco SAC (just hanging as we complete stops) and an OH ****! SAC for when the fecal matter hits the rotating cooling device.

Knowing your baseline gives you a good starting point. Here is a good article by one of our members that goes into some detail on gas planning: Rock Bottom

 

[Dyno Bill]

The Defender badge appears to have been a casualty of the photo attachment fix. It's being looked into and should return shortly.




SAC is a constant, it's based on your surface consumption. You apply your SAC rate to the depth to give you an idea of how much gas you'll use over a given time for that depth. Typically we calculate normal SAC (leisurely dive) working SAC (high exertion/current, etc.) deco SAC (just hanging as we complete stops) and an OH ****! SAC for when the fecal matter hits the rotating cooling device.

Knowing your baseline gives you a good starting point. Here is a good article by one of our members that goes into some detail on gas planning: Rock Bottom

Again thanks, I looked at the link you supplied and it's pretty interesting. I have done planning for a number of dives and taken groups on quite a few tours so I am familiar with the purpose of the calculations. I have always done rec diving with some few side bars and to be honest the figures indicated in the article seemed a bit conservative as with a group the weakest diver sets the pace and of course the nature of the tour is set by the experience of the divers in the group. And from the figures shared I have to say I have broke the rules with regards to depths and tank volumes. But on the brighter side I never lost anyone or got anyone bent. I used to bring everyone back to the swim step shooting at 500 lbs on the bottom and not lower than 400 at the step. I would usually have 800 to 1100 at the step and did on several occasions donate a reg to someone a bit less fortunate. I used to enjoy going off by myself for a longer tour and had to ascended to get shallower using less gas for the return trip, my bad
Thanks again, Bill