The NAPI Safe Diving Principles:

Part 1: Faster Safe Degassing

Introduction

Every diver knows that due to the absorption of nitrogen during a dive it is necessary to degas - that is, to vent the excess nitrogen by spending some time on the surface.

However, if the dive conditions are good, this surface time can become an eternity, and many a diver would like to decrease the time spend, yet still remain safe. NAPI investigates.

Degassing the old fashioned way

The principles for quick degassing have been known for a long time. The problem is that all of them present the diver with some problems. Lets look at the options:

  • Pure Oxygen. This is the best method, yet it is expensive, and thus we will disregard this option completely.

  • A hot tub. A hot tub ensures that the blood vessels dilate. This has the advantage that the circulation is now more open, more parts of the body are accessed, and degassing proceeds faster. The problem is that vaso-dilation is coupled with a drop in blood pressure, and this means that the blood cannot keep the nitrogen in solution and forms bubbles, causing the diver to bend. Thus, we cannot use this method.

  • A jog around the block. Heavy exercise has the advantage of speeding up the circulation. This ensures that the tissues are serviced more often, and together with an increased breathing rate, more nitrogen is vented. The problem is that heavy exercise is usually coupled with vaso-dilation, leading to the same problems mentioned above. Thus, we cannot use this method either.

Degassing the NAPI way

While the above methods for degassing may not work, they do show the essentials required: vaso-dilation to reach the whole body, and increased circulation to speed the venting of nitrogen. But how does one do this safely? Simple.

  • To induce vaso-dilation in a controlled manner, start drinking beers. The first beer has little effect, the next one a bit more, and so on. The gradual dilation ensures that there is no massive drop in blood pressure.

  • Counteracting the small drop in blood pressure is easy; smoke some cigarettes, especially the heavy, unfiltered kind. This should ensure that the blood pressure remains high.

  • The rate of circulation has to be increased without heavy exercise, but this is easily done be reading your favorite issue of Playboy or Playgirl, whichever you fancy.

If of course you do all the above while driving dangerously fast, the adrenalin rush ensures that the effects are increased even more!

As we all know, prevention is better than cure, so to decrease the time to degas even more, make sure you don't absorb too much gas in the first place. This is best done by decreasing the amount of liquid available for nitrogen to absorb in. To do this, just make sure you have a tremendous hangover, as this means you are severely dehydrated. Less liquid means less absorption, so while you could still bend, the bend will be less severe. Drinking beers after the dive now becomes essential, as this ensures you get properly hydrated.

Conclusion

The quick but safe degassing principles discussed here are sure proof that as a diver, living fast does not mean dying young!

Guido Zsilavecz
National Association of Professional Instructors

This page was last updated on : 06 Sep 2011