Ten years ago, my entry-level students were required, by their training agency, to answer a test question having to do with responses to out-of-air emergencies. Students not only had to correctly identify five different possible responses, but rank them in order of desirability (yeah…like they are actually going to remember all that five years from now). Ironically, the best possible response to any out-of-air emergency wasn’t among the choices. That response? Not running out of gas in the first place.
Traditional diver training has always tended to focus on responding to emergencies, rather than preventing them. In the typical entry-level scuba course, little if any time is devoted to gas management. Equally disappointing, among those 20 or more entry-level skills that agencies generally require, none seem to have anything to do with preventing out-of-air situations.
That needs to change. Fortunately, you don’t have to wait until your training agency takes action. There are steps you can take right now to help prevent your students from ever having to rely on one of the five responses mentioned earlier.
Teaching gas management as a skill
As best I can tell, no agency lists gas management on their cue cards or skill slates. This doesn’t mean it can’t be an integral part of how you teach in confined water. Here are two things that can help:
- Establish minimum alert and ascent pressures: Before going under water with students for the first time, make it clear they are responsible for telling you when they reach at least two different pressure values. The first of these would be a simple alert pressure — say, 70 bar/1,000 psi — that lets you know they are beginning to run low on air. The second of these would be the more critical; that is, a Minimum Ascent Pressure (MAP) — typically 35 bar/500 psi or more. This is the point at which they need to be getting out of the water and either ending the session or changing tanks.
- Establish frequent pressure checks: You can tell students that they need to monitor pressure frequently; however, unless you enforce that rule, there is no guarantee they will. One way to do this is, every ten minutes or so, ask students to tell you how much gas they have remaining without looking at their pressure gauges Tell students they are responsible for knowing this within, say, 200 psi. Those who monitor pressure frequently will be able to do this; those who cannot do this consistently may need to incur some sort of penalty.
You can probably think of variations on these techniques that would work particularly well in your teaching situation.
Teach turnaround pressure, MAP and MGR
If your training agency’s learning materials do not cover gas management in sufficient depth, supplement them with information on turn pressure, Minimum Ascent Pressure (MAP) and Minimum Gas Reserve (MGR). You cannot only teach these in theory, but implement them as part of your open-water training dives.
- Turnaround pressure: On any dive involving travel away from the boat, shore or other entry/exit point, divers need to establish a turnaround pressure. This is the point at which they need to turn around and start heading back to the exit, keeping additional gas in reserve for contingencies. Doing so not only helps prevent divers from running out of air, it helps them avoid long surface swims and the risks associated with them. The Rule of Thirds used by cave and tech divers works equally well here. A third out, a third back and a third “just in case.” If not used, part of that last third can be consumed in the immediate vicinity of the exit.
- Minimum Ascent Pressure (MAP): This is the “no screwing around/it’s time to ascend” pressure. What’s worth noting is that MAP can and should vary with depth. While 50 bar/750 psi may be an adequate MAP for shallow water, on deeper dives a MAP of 70 bar/1,000 psi or more may be called for.
- Minimum Gas Reserve (MGR): MGR goes beyond simple MAP values by allowing sufficient air to solve a problem, travel to the ascent point and then make a slow ascent and safety stop — all while sharing gas with another diver. Determining MGRs requires that divers know their Surface Air Consumption (SAC) rate and may be a bit too involved for entry-level courses. It’s a good topic for Advanced and Deep Diver courses, though.
Teaching simple and effective responses to common diving emergencies is an important part of entry-level training. Teaching students how to prevent those problems in the first place, however, is even more important and, ultimately, the best solution of all.