… The term "decompression" and "no decompression" are misnomers…
I think “misnomer” misrepresents the evolution of the terms. My recreational and military training 40-50 years ago used the terms “decompression” and “no decompression stop” dive. Like so many phrases in the English language, verbal shorthand quickly modified it to “decompression” and “no decompression” dives. A “No-stop” dive was also common and is probably technically more accurate in today’s recreational context than “no-deco”.
Designations based on stops started to get blurry in the late 1960s when continuous decompression lasting days quickly dominated saturation diving decompression schedules. This has indirect impact on recreational diving nomenclature because it influenced the hyperbaric research they use.
You should go to the Ask Dr. Decompression forum on ScubaBoard and tell Michael Powell that he doesn't know squat about decompression theory. You should also contact NASA and tell them to scrub all the knowledge his research on decompression gave them over the decades he worked for them because he does not know squat about it….
NASA (and NOAA) is not a recreational diving training agency. Training agencies use research and statistics generated directly and indirectly largely by governments worldwide. Even all the sporadic investments by the worlds’ commercial oilfield diving companies are dwarfed by government funding. It is foolish to think that the world’s recreational diving training agencies have the resources to make significant contributions to the state of the art. However, along with DAN, they have been very instrumental in motivating the comparatively inexpensive analysis of existing research.
This has nothing to do with talent or desire. Hyperbaric research beyond crunching the limited data available and re-analyzing government funded research is horrendously expensive — including animal testing to validate a new theory. Add human testing to the equation and validation outside the military becomes nearly prohibitive in the US due to potential litigation. It always comes down to “what’s the payback” for any business.
Training agencies also are constrained by legitimate legal concerns. Imagine a brilliant new decompression algorithm developed by an employee of a training agency. It wouldn’t matter that it was 5x safer with half the decompression of today’s algorithms. It could never be endorsed without a vast body of evidence and human testing to back it up — your basic courtroom CYA. The two main reasons are the agency wouldn’t make a significant amount of money from the revolutionary new algorithm and the potential legal liability would be staggering.
I grant you that “don’t know squat” might be an overstatement to make the point. Some agencies do associate with accomplished hyperbaric researchers. Sadly, hyperbaric research remains an expensive bastard-child in medicine without a method to monetize the investment.
---------- Post added September 5th, 2014 at 02:22 PM ----------
…In regards to ascent rate according to Alex Brylske in his book "The Complete Diver" the 60 ft/min rate was a compromise between the hard-hat divers who wanted ascent rates limited to 25 ft/min and Navy frogmen who were routinely coming up at better than 100 ft/min.
Apples and oranges. To this day the great majority of special forces (Navy Frogmen) dives are done on pure oxygen closed-circuit rebreathers. I have never heard anyone in the fleet salvage community wanting 25'/minute for reasons already stated.
Edit: Decompression would be continuous if diving medical officers had their way, but it is impractical in the water. 30'/minute is a PITA, imagine an ascent rate varying from 1/10th-10'/minute.