Navy Dive Tables

[tbone1004]

for the OP if the navy tables are a bit hard to wrap your head around, the NAUI tables are based very closely on the navy tables but are one stop short for NDL's so a bit more conservative and a bit easier to meander around for SI's.

 

[Akimbo]

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

Like I wrote, I have read all that in magazines since the 1960s. Just because it has been repeated doesn’t make it viable. It just doesn’t stand up to scrutiny. The story is also inconsistent with what I was told by people who were trained by divers that worked at EDU when the decision was made.

It is well known that everyone except the medical officers wanted 60'/minute… and most of us would like it to return. As explained to me, open circuit Scuba is incompatible with the UDT’s mission. Bubbles are the obvious reason, but duration is equally important. Swims often take 1-2 hours in each direction. Faster ascent rates had no operational importance to the UDT because they had to be on O2 rebreathers anyway, except for training.

On the deep sea gear side, 60'/minute was the standard when I was there and handling the umbilical at that rate was not a problem. Operating the chamber is much easier. I have no doubt that the UDT also wanted a faster rate than 25-30'/minute but that wouldn’t be enough to influence EDU by itself. Heck, I find it very difficult to maintain 30'/minute today without a downline or a computer to whine at me.

Come to think of it, 100'/minute would be an even bigger PITA… aside from giving medical officers convulsions. We could probably find a 100'/minute bubble size to follow but correlating that to a stopwatch for surface supplied and chamber operations would be a nightmare.

Now for the Fun Stuff
In any case, this tiny piece of history will hopefully be even more academic before I’m dead. I have to agree with predictions that foresee the demise of decompression algorithms. They hypothesis is computer and sensor technology will allow direct reading of individuals to determine the safest and most efficient decompression. Ascent rates will be variable, slowing down closer to the surface. Stops will probably still exist but won’t be limited to even 3 meter or 10' intervals.

Computers will also control ascent rates on all chambers, as they do on more advanced systems today. Surface supplied diving isn’t likely to go away but all it will take is a faster/slower display to guide the tender. Scuba, freedivers, non-divers, and medical professionals will all know blood O2 and CO2 levels in addition to dissolved gas in tissues and blood.

Predictions I have read on sensors range from built into the suit to imbedded at birth. Bubble formation being a minor part of their overall function and not intended for divers. Just think how archaic, indirect, and inconsistent measuring blood pressure readings are. The whole “wearable technology” movement is just the very beginning. This is a very big deal for society and will ultimately have useful applications for divers.

 

[EFX]

Like I wrote, I have read all that in magazines since the 1960s. Just because it has been repeated doesn’t make it viable. It just doesn’t stand up to scrutiny. The story is also inconsistent with what I was told by people who were trained by divers that worked at EDU when the decision was made.

No, it doesn't make it viable but I consider it more accurate than your third-hand account which is hearsay. Did your friend dive with Cdr. Francis Douglas Fane of the U.S. Navy West Coast Underwater Demolition Team? Some teams may have been using a 60 ft/min rate. Exceptions don't prove anything. We need a published ascent rate, if there is one, from the 1943 Navy Dive manual.

Now for the Fun Stuff
In any case, this tiny piece of history will hopefully be even more academic before I’m dead. I have to agree with predictions that foresee the demise of decompression algorithms. They hypothesis is computer and sensor technology will allow direct reading of individuals to determine the safest and most efficient decompression. Ascent rates will be variable, slowing down closer to the surface. Stops will probably still exist but won’t be limited to even 3 meter or 10' intervals.

Computers will also control ascent rates on all chambers, as they do on more advanced systems today. Surface supplied diving isn’t likely to go away but all it will take is a faster/slower display to guide the tender. Scuba, freedivers, non-divers, and medical professionals will all know blood O2 and CO2 levels in addition to dissolved gas in tissues and blood.

Predictions I have read on sensors range from built into the suit to imbedded at birth. Bubble formation being a minor part of their overall function and not intended for divers. Just think how archaic, indirect, and inconsistent measuring blood pressure readings are. The whole “wearable technology” movement is just the very beginning. This is a very big deal for society and will ultimately have useful applications for divers.

This is a very interesting topic. I added a new topic called "Advanced technology" under Advanced Scuba Discussions. See my response there.

 

[Sam Miller III]

No, it doesn't make it viable but I consider it more accurate than your third-hand account which is hearsay. Did your friend dive with Cdr. Francis Douglas Fane of the U.S. Navy West Coast Underwater Demolition Team? Some teams may have been using a 60 ft/min rate. Exceptions don't prove anything. We need a published ascent rate, if there is one, from the 1943 Navy Dive manual.

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

1943 US Navy dive manual

"NAVY DEPARTMENT
BUREAU OF SHIPS
DIVING MANUAL
1943

UNITED STATES
GOVERMENT PRINTING OFFICE
WASHINGTON :1943

265 PAGES

Chapter XIV
The Assent
Page 169
(b) The rate of assent of the stage should not exceed 25 feet per minute"

~~~~~~~~~~~~~~~~~~~~~~~~~
EFX
I personally knew (Red Dog) Doug Fane. We chatted about many things over a number of years and when he moved to Florida to live with his son we corresponded by old fashioned US mail with an occasional telephone call. Not once did we ever discuss the rate of assent. I feel honored that he inscribed the original 1956 Naked Warriors to me as well as the 1995 NIP reprint of the Naked Warriors.

It is assumed since you have a whopping less than 200 dives you never heard of him and certainly didn't have the honor of knowing Red Dog Doug Fane


Continue on...It is a very entertaining thread

SDM

 

[Akimbo]

Sam

Do you have the 1952 manual as well? If so, was the ascent rate in the 1952 manual also 25'/minute? Based on this summary Aqualung-style SCUBA was introduced in Part 3 of the 1959 (1958?) manual.

CLASSIC DIVING BOOKS - US NAVY DIVING MANUAL

I have been curious for years.

---------- Post added September 9th, 2014 at 06:10 PM ----------

… This is a very interesting topic. I added a new topic called "Advanced technology" under Advanced Scuba Discussions. See my response there.

Here is the link for those interested:
http://www.scubaboard.com/forums/advanced-scuba-discussions/491597-advanced-technology.html

 

[captain]

I feel confident if any information on the subject may still exists it is in the Navy library and archives at the Washington, DC Navy yard. A few years ago there was a NEDU section in the technical diving section with a NEDU representative. I believe this subject was discussed at the time with the same results as this time. All the old hands are gone from NEDU and probably the old records were left in DC when the NEDU moved to PCB.

 

[Akimbo]

I feel confident if any information on the subject may still exists it is in the Navy library and archives at the Washington, DC Navy yard...

I concur. I would be surprised if all the research papers written at EDU were not preserved, but it's not like they wrote a lot of memos — nothing like we use E-mail and forums today. EDU in DC was a pretty small place and half the building started as a virtual mirror image of the chambers and wet pots for the First Class Diving School. We had tons of space around the chambers on the school side but the EDU-side was crammed full of controls and instruments in the decade before they moved to the Ocean Simulator in Panama City. I doubt that non-essential paperwork like memos were saved outside of personal files.

Most of the decisions were made face to face over beers at the Green Derby across the river anyway.

 

[captain]

I had a conversation with Bernie Campoli about this. He recalls Dr. Charlie Aquadro who was a submarine medical officer assigned to UDT in the 1950's also possibly being involved. Bernie said he went on to work with Cousteau on the Conshelf projects. He also said all NEDU records were eventually transferred to PC. Seems Dr. Aquadro is still living in New Bern, NC.

Charlie Aquadro Shares Tales From Working on Jacques Cousteau's Conshelf Underwater Habitats | Blue Legacy

 

[cocoajoe]

All dives are decompression dives. Dives within the "NDL" just means that the decompression obligation can be accomplished through a relatively slow ascent, and perhaps a stop at 15 feet to be extra safe.

Yeah, I'm familiar with pressure and deco theory. But the NDL term still means no decompression limits which means you don't have "decompression obligation". My question was about the Navy tables not quibbling over dive terms

 

[LeadTurn_SD]

Had an instructor tell me navy tables were based on every dive being a deco dive. That was in response to a question I had about comparing navy table with some other NDL tables. True?

All dives are decompression dives. Dives within the "NDL" just means that the decompression obligation can be accomplished through a relatively slow ascent, and perhaps a stop at 15 feet to be extra safe.

Yeah, I'm familiar with pressure and deco theory. But the NDL term still means no decompression limits which means you don't have "decompression obligation". My question was about the Navy tables not quibbling over dive terms

I think, actually, it is terminology that might have caused your instructor to answer your question the way he did... but if he believes the other tables were constructed with a different overall "Reality" regarding the physiology of the human body and how it reacts to compressed gas at depth, then no, I think he was wrong.

The concept that your tissues will load inert gas during a descent and offload that gas on ascent is not debated by the folks constructing and tweaking the various tables. It is a given. They know that. Their debate goes deeper, but in the end revolves the most efficient way to get a diver safely back to the surface, and here is where the tables and overall procedures have (and continue to) evolve.

So if your instructor really believed that what made the Navy tables different was the concept that "every dive is a deco dive", then no, I'd day that he/she was incorrect.... all the tables are working on that physiologic premise.

The terminology is what trips folks up I think.

Best wishes.