I read something recently that fits in well with everything I’ve been doing and thinking lately regarding SCUBA diving. I don’t remember where I saw it, but it was a piece about gas consumption and SAC rate calculation for sport divers.
Obviously, in sport diving, the diver has direct access to the surface. However, although diving accidents are rare, those that do occur are almost always associated with running out of air. With that in mind, I think it makes sense for divers to learn to use SAC rate calculations to better plan their dives.
I’m not advocating changes to open water SCUBA training, but rather to encourage divers to take it upon themselves to improve their gas planning skills.
In an earlier post, I linked to an online SAC rate calculator. Any diver has the ability to do a SAC swim on a dive. Simply, that means swimming for a set duration and a fixed depth and noting the tank pressure before and after the swim. In tech diving, we do these often, and at varying levels of exertion. The more often you measure your SAC rate, the more confident you’ll become in it’s accuracy.
Once the SAC rate has been determined, a simple formula provides the gas requirement for a given dive. Although the diver will most likely be using a single 80 cu. ft. SCUBA cylinder, dive planning using a known SAC rate, promotes better awareness and an added margin of safety.
I believe the process also makes you a better (and safer) diver. SAC swims require good buoyancy skills and close monitoring of depth and tank pressure. This type of practice is fun and helps to build confidence by increasing awareness and control.