Which is it- 60fpm or 30fpm for ascent??

[BIGJC]

Why do they teach new divers how to ascend by telling them a rate? why not just say something like stop every ten feet for 30 seconds to a minute or something a little more tangible than (60 fpm).....

slow=good fast=bad, it is just that simple especially in recreational diving....

 

[Dr Deco]

BigJC:

Ascent Rate

The concept of fast ascent rate is traceable to the Haldane concept of tissue gas loading. The original method of ascent devised by the French physiologist Paul Bert in 1880 stated that the ascent should be slow and linear (e.g., 5 feet/min). This lead to problems of DCS when the depths were greater than about 100 feet.

Haldane thought that the problem was traceable to dissolved nitrogen entering the tissues during the slow ascent since, he believed, too much time was spent at the deeper depths. His plan, the well-known Haldane method, was to quickly ascend to a stage much shallower and allow off gassing to occur but still remain deep enough so that bubble formation would be precluded. The Haldane method was predicated on the concept that bubbles did not form during the ascent. It is clear from this that rapid ascent to the surface was an important part of the method. . You did not want to pause at deep depths.

Deep Stops

Deep Stops is a relatively new concept championed most strongly in the past decade by Bruce Wienke, PhD. He is not the first to suggest this, however, as it was a part of Brian Hills, PhD, Thermodynamic Method (1968). Hills suggested that divers should remain deeper and ascend faster to a point near the surface where they would then ascend directly to the surface from 30 FSW.

For recreational divers, the slow vs. fast ascent and deep stops vs. quick ascent to the first stop is relatively new.

Dr Deco :doctor:

Readers, please note the next class in Decompression Physiology :grad:
http://wrigley.usc.edu/hyperbaric/advdeco.htm