Navy Dive Tables

[Akimbo]

… 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.

 

[boulderjohn]

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.

When PADI did its research to create the RDP, they did original research on new divers using new methods, including Doppler bubble imaging to check for the formation of bubbles in the divers' blood. Dr. Michael Powell was included as a researcher because of the expertise he developed on decompression theory working for NASA. (Decompression is a serious issue for astronauts.) They did not just review existing research.

 

[EFX]

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.

The context of my response and preceding comments regard the past when the US Navy decided on the 60 ft/min ascent rate. The ascent rate was based on air dives using OC scuba. Special forces, pure oxygen, rebreathers, and anything else you care to extrapolate from our comments is "apples and oranges" to the ongoing discussion.

 

[Akimbo]

When PADI did its research to create the RDP, they did original research on new divers using new methods, including Doppler bubble imaging ...

Doppler imaging was hardly new in the mid-1980s. EDU was using them on us on the Mark II Deep Dive System in 1972 and I had heard about them several years earlier. IMHO it is a stretch to call RDP more than a minor evolution to existing work.

Development and validation of no-stop decompression procedures for recreational diving: the DSAT recreational dive planner.

What we are basically talking about here is a set of no-decompression stop management tables/analog calculators with slightly extended reped schedules that are largely based on US Navy tables of the day.

Quoted from the abstract above:

“The RDP was developed by adapting the Haldane computational algorithm used by the U.S. Navy to the special needs of recreational divers. We derived no-stop limits for the recreational range of 40 to 130 fsw from Spencer's (1976) empirical data on bubble development in divers detected using Doppler ultrasonics.”

The most significant part of these studies was the introduction of females to the mix.

---------- Post added September 5th, 2014 at 04:52 PM ----------

The context of my response and preceding comments regard the past when the US Navy decided on the 60 ft/min ascent rate. That has nothing to do with what any diver does today. Furthermore, the ascent rate was based on air dives. Special forces, pure oxygen, and anything else you care to extrapolate from our comments is "apples and oranges" to the ongoing discussion.

I’m confused, your quote was comparing air dives in the salvage side (hard hat) of the Navy to special forces (Navy frogmen).

…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.

Perhaps I should have been clearer. The vast majority of special forces dives in all branches of the military have been on pure O2 rebreathers from the beginning in WWII. There was never a reason to make the ascent rates of surface supplied air divers and pure O2 rebreather divers the same. There are no decompression tables or limits on pure Oxygen, aside from not descending below 25' to avoid OxTox (20' today).

My understanding from several US Navy Master Divers was the main motivation for 60'/minute was it matched the number of seconds on their stop watches. From personal experience operating old Navy chambers with large gate valves, they are right. It is much easier to adjust the flow on a 1:1 basis than even 1:2 like 30'/minute… especially with a cigar chomping Master Diver breathing down your neck.

 

[EFX]

I’m confused, your quote was comparing air dives in the salvage side (hard hat) of the Navy to special forces (Navy frogmen). Perhaps I should have been clearer. The vast majority of special forces dives in all branches of the military have been on pure O2 rebreathers from the beginning in WWII. There was never a reason to make the ascent rates of surface supplied air divers and pure O2 rebreather divers the same.

Navy frogman may not be the correct designation. The comparison was between navy divers on OC scuba air, whether they be special forces or not, and navy hard-hat divers on surface supplied air. The Navy wanted one standard for ascent rate on scuba OC air. Why this has anything to do with hard-hat divers on surfaced supplied air is beyond me.

 

[Akimbo]

Navy frogman may not be the correct designation. The comparison was between navy divers on OC scuba air and navy hard-hat divers on surfaced supplied air regardless of the mission (salvage, rescue, etc. ). The Navy wanted one standard for scuba OC air. Why this has anything to do with hard-hat air surfaced supplied divers is beyond me.

OK, that sort of makes sense. What doesn’t compute is that Navy open circuit Scuba divers were ascending at 100'/minute. That sounds like a sea story.

Here’s the Reasoning:
Training on open circuit Scuba has been the same for all Navy divers since it was introduced — excluding Special Forces. The physiology is the same for all air divers, hard hat (surface supplied) and Scuba (open circuit or closed and semi-closed circuit mixed gas rebreathers). I could be mistaken but I believe that the ascent rate was already at 60'/minute when the “Aqualung” was introduced in the Navy… in the 1959 Navy Diving Manual I think. The previous edition of the manual was 1943, before Cousteau tested the first Aqualung.

Knowing how regimented that navy diving is, I am sure the diving officer would take immediate action if he (all male in those days) knew anyone was ascending faster than Navy air tables allowed. His career was on the line when divers got hurt or bent too often. Everyone knew there would be serious consequences so wouldn’t admit to doing it, especially to EDU (Experimental Diving Unit) who developed the tables.

Frogmen:
I believe the term Frogmen was originally coined by print media for the Scouts & Raiders, which soon became the UDT (Underwater Demolition Teams). They were basically combat swimmers/commandos and began during WWII with breath hold diving, but got pure O2 rebreathers soon after. Their roll significantly expanded when the SEAL (SEa Air Land) teams were created by the CNO (Chief of Naval Operations) in 1961 and has since taken over the UDT. Their training has always been separate from Navy Divers, Scuba and hard hat.

 

[captain]

My oldest Navy diving manual is 1958 so I can't speak of what was in it before. It does cover the AquaLung. UDT was using the Aqua Lung in the early 50's. Notice the use of the early triples.

[video=youtube;C3amH7t1GgI]https://www.youtube.com/watch?v=C3amH7t1GgI[/video]

A lot of early UDT history here.

NavalSpecialWarfareArchives

 

[Akimbo]

My oldest Navy diving manual is 1958 so I can't speak of what was in it before. …

1958 or 59? Is this a misprint?
CLASSIC DIVING BOOKS - US NAVY DIVING MANUAL

I had that manual from my Scuba Class but, like an idiot, threw it away when the 1963 Manual came out. Dumb!

Other than the reprint of the 1916 manual, I have never seen any of the ones that came out in between. Any of them would be a great score for a collector.

 

[captain]

It says September 1958. The one I have came from an old UDT guy named Christensen who was in team 2.

 

[EFX]

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.

OK, that sort of makes sense. What doesn’t compute is that Navy open circuit Scuba divers were ascending at 100'/minute. That sounds like a sea story.

Nope. Not a sea story. Here is an excerpt from AlertDiverOnline:

"U.S. Navy frogmen generally wanted to ascend from their dives and exit the water quickly, but such quick ascents were impractical for hardhat divers. Thus, a compromise of 60 feet per minute was reached. This ascent rate remained in place for many years even as dive tables continued to be refined. It was not until about 20 years ago that the U.S. Navy changed their recommended ascent rate to 30 feet per minute". - See more at: Alert Diver | Ascent Rates

From DAN:

"Then in 1958, during the production of the U.S. Navy Diving Manual, the rate of ascent to be proposed came under review. Cdr. Francis Douglas Fane of the U.S. Navy West Coast Underwater Demolition Team wanted rates for his frogmen of 100 feet (30 meters) per minute or faster. The hardhat divers, on the other hand, considered this impractical for the heavily suited divers who were used to coming up a line at 10 feet (3 meters) per minute. Thus, a compromise was reached at 60 feet (18 meters) per minute, which was also a convenient 1 foot per second." - See more at: https://www.diversalertnetwork.org/default.aspx?a=news&id=514