Endurance Diving

[D-Boy]

What are the effects on the body from endurance diving (Two hours +)? I've heard stories of dives reaching as far as nine hours. I'm sure it's possible but do you need specialized mixed gas rigs? If so, what? I know SDV Teams do this on a regular basis so I would kind of like to know how. Are there Increased off gasing plateus, etc. Any information is great!!!!
D-Boy out.

[Kolt]

D-boy,

As far as diving with air is concerned, the limiting factor physiologically speaking is your depth. The other obvious physical factor is how much air supply you have in your tank(s). The deeper you go, the more air you breathe due to the increased pressure and also the more nitrogen from the air gets disolved in your blood also due to the increased air pressure at depth.

Now with mixed gas diving, things are much different. There are different concentrations of oxygen and nitrogen in the case of Nitrox diving. (Nitox is not truely mixed gas, it just has different concentrations or the same gases found in air). Helium is intoduced into some mixed gas mixtures to reduce the amount of nitrogen (both are inert gases) so that takes away from some of the nitrogen building up in you blood.

In all cases you can dive for however long you want (within reason and the limitations of you equipment), but you will need to allow the time for decompression so you don't get the bends from the nitrogen. What this entails is stopping at different depths below the surfaces for different amount of times, specified in the dive tables, to allow the nitrogen to go back into you blood as a liquid. You also need the air to breath at these depths and they are usually for long periods of time so prestaged air is a must.


Many ship repair people dive from surface supplied air (no tanks) for extended period and because they are not diving deep, relatively speaking, they can stay down for prolonged periods of time.

If you can, get you hands on some dive tables. These, along with the intructions in their use, will explain this much better than I can here.

This is why all dives are planned and calculated. Most dives are planned to have no decompression stops, at least in the recreational sense.

Hope this helps.

Kolt