by
Larry "Harris" Taylor, Ph.D.
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The "air check ritual" became a part of my diving as a result of the following incident.
Much of my diving is drift diving in the extremely swift water of the St. Clair River at Port Huron. There are 1-2 scuba deaths every year in this river. The NOAA measured current flow here is in excess of 90 million gallons a minute. It is not a place for novice divers. (I do NOT train divers to play here without a minimum of 50 dives.) Since we may drift a mile or more per dive, it is common practice to suit up at the exit point, load all the gear into one of the on-site vehicles, drive upstream to the entry point and go diving. We commonly check cylinder pressure at the assembly point and then turn the air valve off for transport. To prevent overheating on the surface during hot, humid days, we try to minimize our time at the entry point. Typically, we drive to the site, quickly put on gear and jump into the water.
The entry point at the mouth of the St. Clair river involves climbing over a 4 foot rail fence that lines the walkway along the river bank. There is only a very narrow edge on the river side of the barrier. We climb over the rail with one fin on, (height of rail and length of fins makes climbing the fence with both fins on most difficult), secure position on the narrow ledge, put on the second fin and then drop 8-10 feet into water moving in excess of 2 knots. Because we wish to minimize our surface travel distance on entry, we typically deflate our b.c. 's prior to the entry. So, we hit the water a bit heavy and immediately start sinking. Typically, I enter the water first and my buddy enters the water about 10 seconds later from a point about 20 feet upstream from me. This way, my buddy descends directly to a rally point at the bottom. We do a quick check of gear and then start the drift.
On one very sticky day, we moved rapidly to the site, climbed over the rail and entered the water. As usual, the shock of hitting colder water was an instant relief to the over-heating that had occurred on the surface. However, it became readily apparent on my second breath that I had forgotten to turn on my air. I can assure you that descending in cold, swift water without air is stressful!
After the dive, I decided from then on, I would breathe several times on the regulator before entry to prevent this stupid mistake from occurring again. The idea is that should you (or someone else) turn off your air after initial pressure check (for transport, or perhaps to stop a leak), the gauge will read full and there will be a few breaths available from the air contained in the hose between the first and second stage. But 4 breaths should be enough to consume this in-hose air, so if the spg goes to zero during the ritual, then the air valve is off, even though the gauge reads full. It is much easier to take care of this problem (air valve turned off) on the surface than at-depth.
So, the air-check ritual done immediately prior to entry is:
1. Look at the spg and ensure that cylinder is full.
2. Breathe 4 times.
3. Look at spg again.
4. If the cylinder pressure has not gone to zero, then you have air for the dive.
5. If the cylinder pressure has gone to zero, then turn on the air before getting into the water.
The point is:
We, as humans, are not perfect creatures and we WILL MAKE MISTAKES. The purpose of training is NOT to eliminate all errors; it is to make these errors that will occur because of our imperfect nature nothing more than an inconvenience, instead of a life threat.
So, prior to every entry, look at the pressure gauge, breath through the regulator four times, and then look at the gauge again. If the gauge is zero, turn on the air. If the gauge is at full cylinder pressure, then enter the water and enjoy your all-too-brief adventure in Planet Ocean.
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About The
Author:
Larry
"Harris" Taylor, Ph.D. is a biochemist and Diving Safety Coordinator at the
University of Michigan. He has authored more than 200 scuba related articles.
His personal dive library (See Alert Diver, Mar/Apr, 1997, p. 54) is considered
one of the best recreational sources of information In North
America.
All rights reserved.
Use of these articles for personal or organizational profit is specifically denied.
These articles may be used for not-for-profit diving education