State of the art...

[DeepSeaDan]

Dear Doc...

Having been retired from sat. diving for some time now I am curious as to where we are with respect to breathing gas development for great depths.

The last I remember was Duke U. experimenting with a variety of mixes around the 2200' level & I seem to recall they were stymied in gettting around the problem of he. tremors.

If memory serves me correctly ( not likely...my brain is now nothing but a froth of micro-bubbles! ) the deepest working dive logged in @ 1800'...have they gone deeper?

Your assistance is appreciated.

Regards,
D.S.D.

 

[Dr Deco]

Dear DeepSeaDan:

If memory serves me correctly, the deepest dive in the United States (and I believe the world) occurred in a chamber at Duke University. This was to 2,250 fsw and was performed with trimix, a mixture of helium, oxygen, and nitrogen. It was a chamber dive; I do not know the deepest working, open water dive.

You are correct in stating that one goal of these studies was to reduce the tremor problem of rapid compression. This is known as the High Pressure Nervous Syndrome or HPNS. The origin of this malady is not known, but it does not manifest itself if the compression is slow or the dive is not to about 500 feet. By slow, I mean taking a day to reach 1,000 fsw. Even adding narcotic nitrogen does not eliminate this problem completely.

The difficulty arose more when one wished to perform a rapid descent, a short bottom time, and then an ascent - - a so called “bounce dive.” Today, such work would probably be performed by underwater robots. It is my undersatanding that there is not too much deep water work being performed in the open water today.

Dr Deco