Gas Management

Planning and monitoring breathing gas through a dive, using consumption rates, reserves, and turn points so no diver approaches an out-of-air situation.

Gas management is the discipline of making sure the gas in your cylinders always exceeds what the rest of the dive can demand of it. It starts before the dive: knowing your SAC rate, computing what the planned depth and time will consume, and deciding on reserves and a turn pressure. Underwater it becomes a habit loop: check the SPG regularly, compare against the plan, and communicate remaining pressure to your buddy at agreed points.

Different environments use different rules. Open water recreational divers commonly plan to start the ascent with a healthy reserve and surface with no less than 50 bar (700 psi). Overhead and technical environments demand more formal methods: the rule of thirds for penetration dives, and rock bottom or minimum gas calculations that reserve enough for two divers to share gas from the deepest point to the surface.

Recording start and end pressure for every dive turns each entry in your log into a data point: over time you see your real consumption at different depths and workloads, and future plans rest on measured numbers instead of guesses. The habit also exposes problems early, since a sudden jump in consumption often flags a leak, poor trim, or creeping anxiety worth addressing.