- Messages
- 93,383
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- On the Fun Side of Trump's Wall
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Not something I learned wrong, but something I saw taught wrong....
An AI was teaching some OW students about SAC rates. On the previous dive he had them calculate their resting SAC rates (sitting on the bottom, resting for 1 minute). He was now during their SI having them calculate their required gas for the next dive based on those resting SAC rates. :shocked2: To ignore rock bottom is one thing, but to instruct OW students who do not know any better to vastly underestimate gas consumption, and then plan dives on that faulty information (given that most of us do not own scooters and must actually "fin" to get anywhere on a dive) was ridiculously stupid and dangerous (not necessarily during the class, but for future dives conducted now with no safety margins). Not that I'm advocating it, but better to not teach SAC's at all and leave it at surface with 500psi.
I'll give the dude props for teaching it at all ... most instructors don't. I've met many who think it's not needed ... that telling someone to watch their gauge and abort the dive at 500 psi is sufficient (sure it is ... that's why OOA is so common). But it's far easier to fill in the gaps if you know a certain type of knowledge exists.
I teach that SAC rate is not a number ... it's a range, and that your actual usage depends on a lot of variables such as diving conditions, swimming speed, and several other factors that can vary day to day, dive to dive. I liken it to the MPG on your car. You can use an "ideal" number as a baseline, but then you have to factor in what's going to affect it if you want to know how far you can make it on a tank of gas.
... Bob (Grateful Diver)