Monitoring air . . . and . . . how much at depth?

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Posted by Ken Kurtis on September 05, 2001 at 12:19:14:

Jim Hoffman made a great point below ("They Just Don't Get it") about divers not being aware of how MUCH air they have at depth, and that 500psi at 140' in an OOA situation spells trouble.

Food for thought for the group and hopefully something you might want to build into your diving routine.

In ALL of the Reef Seekers briefings, we suggest that you use your depth times 10 as a rough air pressure guide as to when to surface. From 140', that would be 1400psi. From 100', 1000psi. Specifically for Fransworth, given the way most people dive it, it'll mean starting up the anchor line (NOT beginning your search for it) probably with no less than 800psi.

We also suggest you should be back at the 15' 3-minute safety stop with 500psi (which should last a long time at that depth) and on the surface with at least 300psi.

There's no sin in arriving at the surface with "too much" air. But it's certainly a problem if you don't have enough.

As far as monitoring air during the dive, I encourage my students to dive with the pressure gauge (or air-integrated computer) in their left hand at ALL times. It certainly makes it easier to find the gauge and, by having it actually in your hand and "feeling" it there, I feel it encourages you to look at it more often.

I also teach them that I should be able to cover the gauge at any time and ask them their air pressure, and they should know it within a couple of hundred psi. If they don't they're not checking often enough.

I also tell them that if 500 psi has passed since the last time they checked, then they're waiting too long and not looking often enough.

Absent equipment failures, running out of air is 99.99% of the time due to diver inattention. By stressing (and actually doing) frequent monitoring, and starting your ascent to the safety stop with an appropriate amount of air, you should be able to avoid an OOA problem all together.

Ken Kurtis
NAUI Instr. #5936
Co-owner, Reef Seekers Dive Co.,
Beverly Hills, Ca.

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