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trekkindave
08-21-2008, 08:43
Couple of weeks ago when i was getting ready for my open water class, I stumbled across the US Navy Diving Maual. I read through it quickly, well at least as quickly as somone can read through 1000 pages, and it seems to be pretty much all encompassing.

The part that interested me the most, aside from the in depth dive physiology section, as the US Navy Diving Charts.

Does anyone here have any experience diving using the US NAVY no decompression charts, or any charts other then the PADI charts? Realizing that computers have almost replaced charts.

gregor
08-21-2008, 09:03
I've used navy tables when taking a scientific diving course. all dives carried out under the banner of the college had to follow the navy tables. I'm pretty sure all dive tables (navy,PADI,NAUI) come from similar algorithms, the others just have some padding in them since most of us are not as physically sound as a navy diver, also the navy has recompression chambers within a few feet of almost all dive ops.

monant
08-21-2008, 09:37
I either read this or was told this by an instructor in the 1986/1987 timeframe. The Navy developed their original dive tables by observing divers after they surfaced from controlled dives. In effect the sailors were human guinea pigs. My first SCUBA instructor said by following these tables to the letter, a diver still had a slim chance of DCS so he advocated padding them for safety. I don’t recall the actual percentage of DCS the diver was at risk for but I think it was 5%. My first instructor also had several friends who were commercial divers. They said that many commercial divers experience joint pain of varying degrees after many years of diving, much of which was saturation diving. The only tables available to them at that time were those developed by the Navy.
I have since read about the PADI dive tables. I originally thought they just added 5 minutes of padding for safety but actually DSAT (Diving Science and Technology) used doppler equipment to actually detect micro bubbles in the blood of divers diving on pre PADI dive tables. After adding extra time to the maximum depth limits they were no longer able to detect micro bubbles in the blood of these test divers. It is my belief that these micro bubbles in the blood of early commercial divers over many years of diving were the cause of their joint pain.
I don’t have any references for what I have written so please check for yourself. In doing so you will likely learn other aspects of diving physiology and history.

Lone Frogman
08-21-2008, 09:47
following these tables to the letter, a diver still had a slim chance of DCS

This is true with all tables.

BouzoukiJoe A.K.A. wrecker130 AKA Chuck Norris AKA joeforbroke (banned)
08-21-2008, 09:48
I either read this or was told this by an instructor in the 1986/1987 timeframe. The Navy developed their original dive tables by observing divers after they surfaced from controlled dives. In effect the sailors were human guinea pigs. My first SCUBA instructor said by following these tables to the letter, a diver still had a slim chance of DCS so he advocated padding them for safety. I don’t recall the actual percentage of DCS the diver was at risk for but I think it was 5%. My first instructor also had several friends who were commercial divers. They said that many commercial divers experience joint pain of varying degrees after many years of diving, much of which was saturation diving. The only tables available to them at that time were those developed by the Navy.
I have since read about the PADI dive tables. I originally thought they just added 5 minutes of padding for safety but actually DSAT (Diving Science and Technology) used doppler equipment to actually detect micro bubbles in the blood of divers diving on pre PADI dive tables. After adding extra time to the maximum depth limits they were no longer able to detect micro bubbles in the blood of these test divers. It is my belief that these micro bubbles in the blood of early commercial divers over many years of diving were the cause of their joint pain.
I don’t have any references for what I have written so please check for yourself. In doing so you will likely learn other aspects of diving physiology and history.


I read essentially the same thing in the book "Essentials of Deeper Sport Diving" The book is a bit dated, but if I recall, the book claimed the navy redid its tables which were based on the work of Haldene to create 2 values- the 5% DCS risk value and the 1% DCS risk value. The original tables were too risky form some profiles and too conservative for others. I don't recall which version of the Navy tables formed the basis for the DSAT (PADI RDP) tables.

MSilvia
08-21-2008, 10:01
Realizing that computers have almost replaced charts.
I stopped diving with a computer, and don't even own one anymore. They don't do me much good on most of the dives I do (too shallow to matter, to square to benefit, or deco), and I prefer understanding and planning my dives to blindly following battery-powered instructions.

Does anyone here have any experience diving using the US NAVY no decompression charts, or any charts other then the PADI charts?
I've used USN tables, current PADI tables, and the less conservative PADI tables that were in use when I got my OW certification. I have others available, but haven't seen much need to use them, as I also frequently generate my own VPM-B tables with whatever degree of conservatism I feel is appropriate using vPlanner software.

stairman
08-21-2008, 11:38
I rely on two dive computers and dont bother with tables.My dives are mainly caves and far from square profiles.If I figure my dives by max depth Im off the table anyways.If I show deco after a dive I go by the most conservative of the two.Also compare with buddys computer[s].If solo I dont do deco dives.

BuzzGA
08-21-2008, 16:37
I learned on a set of Navy tables when I got my OW in 1985...I still have them in my bag and use them as a back up to my computer.

navyhmc
08-22-2008, 02:11
The original PADI/NAUI/YMCA tables pre '88 were essentially simplified and condensed Navy tables of no decompression diving. The newer tables are modified navy tables that have a safety factor built in.

The original PADI tables had NDL of 60 minutes for 60fsw. The current tables have a 60fsw NDL of 55 minutes.

And as has been discussed on numerous occasions on ST, while computers make things simpler and in a lot of cases safer, a computer should never replace learning and using tables as a backup.

trekkindave
08-22-2008, 06:20
I notice that in your example the bottom time was 5 minutes different.. is that perhapse why they claim if you go over your time by no more them 5 minutes you can still make a normal no decompression asscent? its one of those little small print things on the botttom of the RDP

FishFood
08-22-2008, 07:13
To elaborate on what monant stated...

Navy Divers can't dive w/o being X number of miles close to a chamber. The Navy dive tables are not for rec divers.

captain
08-22-2008, 11:15
To elaborate on what monant stated...

Navy Divers can't dive w/o being X number of miles close to a chamber. The Navy dive tables are not for rec divers.

Used them for 20 years with no problems. You can get bent for no good reason using any table or computer.

in_cavediver
08-22-2008, 11:16
I notice that in your example the bottom time was 5 minutes different.. is that perhapse why they claim if you go over your time by no more them 5 minutes you can still make a normal no decompression asscent? its one of those little small print things on the botttom of the RDP

In a simple word - Nope. The tables are different and were created using a different algorithm. The rules and procedures were developed for each table/model.

You will hear discussion about decompression models - haldanes, buelhman, VPM, RGBM etc. All of these are attempts to model what is going on in the human being and predict a profile to get the diver up safely. There are lots of modifications as well - gradient factors and pyle stops. Some are based on math - some are seat of your pants. Computers and tables use one of the models and provide you information.

In the end, you need to look at the models and decide which fits you and your body. Some are know to be liberal such as the Navy Tables. IE, lots of bottom time. Others, such as some Sunto computers are quite conservitive and give less available bottom time. Which is right - well, neither really. One likely is a better fit to you though. I lean to the conservitive side. (I also have deco training so I do the bottom time I want anyway - whats a few more minutes under water)

gr8fluke
06-08-2009, 18:49
Just a personal opinion. I've been diving the navy tables for over thirty years. Never seen a problem with divers who used them correctly and witnessed several accidents among divers who didn't. NAUI tables are conserviative and PADI even more so. If every organization copywrites and sells their own version, seems like they have to come up with some kind of difference in order to differentiate their product and market it. Can't imagine why I would want to recuce my bottom time so PADI can make even more money.

Time flies like the wind fruit flies like bananas.

Gr8Fluke

navyhmc
06-08-2009, 21:15
Also remember that the navy tables are based on navy divers. They were developed over years of research and studies. The navy tables use a healthy young adult in excellent physical shape. If you're young and in great shape, you'll be fine. As we get older, we off gas a lot slower and can get into trouble, especially if we're doing repetative dives. That is where most rec divers get into trouble: repetative dives.

I too dove navy tables for years. No problems and never got bent. Of course I was younger and in better shape than I am now. I don't mind the conservativism of the PADI table so that is what I use. It all comes down to personal choice in the end.

Wormzer
06-18-2009, 10:46
My YMCA tables (1991) indicate a NDL at 60 feet to be 50 minutes. Pretty conservative.

On the backside of the YMCA table is the US Navy air decompression table, indicating a NDL at 60 feet to be 60 minutes. It also includes times for decompression stops at 20' and 10' when NDL is surpassed.

fire diver
06-18-2009, 15:21
Just a personal opinion. I've been diving the navy tables for over thirty years. Never seen a problem with divers who used them correctly and witnessed several accidents among divers who didn't. NAUI tables are conserviative and PADI even more so. If every organization copywrites and sells their own version, seems like they have to come up with some kind of difference in order to differentiate their product and market it. Can't imagine why I would want to recuce my bottom time so PADI can make even more money.

Time flies like the wind fruit flies like bananas.

Gr8Fluke

Well, since you dragged up almost a year-old dead thread, I'll respond. Diving the Navy tables is just plain stupid! The tables were developed based on observations, and them adjusted on the basis that the navy has surface recompression cabalilities. They didn't care if thier divers got bent, they could fix them fast enough. So, unless a person in carrying thier own chamber around with them, they are playing russian-roulette. Even the navy is cahnging thier own tables based on doppler reading of micro bubbles in the blood stream. They just haven't finalized them for publishing yet.

CompuDude
06-18-2009, 15:43
Just a personal opinion. I've been diving the navy tables for over thirty years. Never seen a problem with divers who used them correctly and witnessed several accidents among divers who didn't. NAUI tables are conserviative and PADI even more so. If every organization copywrites and sells their own version, seems like they have to come up with some kind of difference in order to differentiate their product and market it. Can't imagine why I would want to recuce my bottom time so PADI can make even more money.

Time flies like the wind fruit flies like bananas.

Gr8Fluke

Well, since you dragged up almost a year-old dead thread, I'll respond. Diving the Navy tables is just plain stupid! The tables were developed based on observations, and them adjusted on the basis that the navy has surface recompression cabalilities. They didn't care if thier divers got bent, they could fix them fast enough. So, unless a person in carrying thier own chamber around with them, they are playing russian-roulette. Even the navy is cahnging thier own tables based on doppler reading of micro bubbles in the blood stream. They just haven't finalized them for publishing yet.

That's not true at all. Of COURSE the Navy cares if they got bent. Bent divers can't complete missions.

The Navy does, however, have a different idea of "acceptable risk" than most recreational divers.

FWIW, the 60', 60 min data point on Navy tables (and other old tables) is the main point at which things seem to break down. Lots of people get bent at that point. (The old "120 rule" also breaks down there... need some padding there, as other tables suggest)

John Yaskowich
06-20-2009, 10:41
I don't mind the conservativism of the PADI table so that is what I use. It all comes down to personal choice in the end.
I did the TDI Nitrox course last night. The tables used in the reference book and exercises is the TDI version of US Navy Dive Tables. The second last review question has EAN34 at 100ft for 33 minutes. The EAD is 80ft. Just for fun and practice I ran the exercise using my PADI tables. 33 min @ 80ft is off the chart on PADI! The PADI NDL for 80ft is 30min, the Navy table allows 40 mins!

The PADI tables are very conservative:
Depth..Navy..Padi
35........310..205
50........100...80
60.........60....55
90.........30....25
They both give 10 min at 130ft.

I wonder how other tables stack up.

navyhmc
06-20-2009, 15:48
I don't mind the conservativism of the PADI table so that is what I use. It all comes down to personal choice in the end.
I did the TDI Nitrox course last night. The tables used in the reference book and exercises is the TDI version of US Navy Dive Tables. The second last review question has EAN34 at 100ft for 33 minutes. The EAD is 80ft. Just for fun and practice I ran the exercise using my PADI tables. 33 min @ 80ft is off the chart on PADI! The PADI NDL for 80ft is 30min, the Navy table allows 40 mins!

The PADI tables are very conservative:
Depth..Navy..Padi
35........310..205
50........100...80
60.........60....55
90.........30....25
They both give 10 min at 130ft.

I wonder how other tables stack up.

Depth..Navy..Padi...SSI...NAUI...?
35........310..205...205...none...
50........100...80...70......80......
60.........60....55...50.....55......
90.........30....25...25.....25......

I couldn't find examples of the SDI tables.

John Yaskowich
06-20-2009, 17:25
Depth..Navy..Padi...SSI...NAUI...?
35........310..205...205...none...
50........100...80...70......80......
60.........60....55...50.....55......
90.........30....25...25.....25......

I couldn't find examples of the SDI tables.
Since TDI is an off-shoot of SDI (or is it the other way round?) I would assume they use the same version of the Navy tables.

navyhmc
06-20-2009, 18:10
Depth..Navy..Padi...SSI...NAUI...?
35........310..205...205...none...
50........100...80...70......80......
60.........60....55...50.....55......
90.........30....25...25.....25......

I couldn't find examples of the SDI tables.
Since TDI is an off-shoot of SDI (or is it the other way round?) I would assume they use the same version of the Navy tables.

Probably, but I couldn't find them on line to post the numbers. SDI is definitely leanining towards computer use vs. tables anyway. I was amazed by how conservative SSI was, especially in the midrange depths.

fire diver
06-20-2009, 20:30
TDI's Deco Procedures book lists the NDL tables from USN, modified USN, DCIEM, and Buhlmann. They also list the USN and Buhlmann deco tables.

I still wouldn't use those for deco either. Too many advances have been made since those tables were published.

navyhmc
06-20-2009, 20:37
I was advised once that one of the problems with using a pure Buhlmann was that it is not intended for repetative dives, only a single dive. It is modified for multiple dives, but is not quite as accurate in those situations. Which is one reason that USN tables don't use a pure Buhlmann.

petronius
06-27-2009, 19:59
I notice that in your example the bottom time was 5 minutes different.. is that perhapse why they claim if you go over your time by no more them 5 minutes you can still make a normal no decompression asscent? its one of those little small print things on the botttom of the RDP


The fine print on my PADI table says "If a no decompression limit is exceeded by no more than 5 minutes, an 8 minute decompression stop at 15 feet is mandatory. Upon surfacing, the diver must remain out of the water for at least 6 hours..."

If the NDL is exceeded by more than 5 minutes, a 15 minute stop is urged and 24 hours out before the next dive.

captain
06-28-2009, 11:10
I was advised once that one of the problems with using a pure Buhlmann was that it is not intended for repetative dives, only a single dive. It is modified for multiple dives, but is not quite as accurate in those situations. Which is one reason that USN tables don't use a pure Buhlmann.

The Navy tables tend to be more liberal on the first dive and more conservative on repetive dives than other tables, so just looking at the NDL's is not a true comparison.

navyhmc
06-28-2009, 20:17
I was advised once that one of the problems with using a pure Buhlmann was that it is not intended for repetative dives, only a single dive. It is modified for multiple dives, but is not quite as accurate in those situations. Which is one reason that USN tables don't use a pure Buhlmann.

The Navy tables tend to be more liberal on the first dive and more conservative on repetive dives than other tables, so just looking at the NDL's is not a true comparison.

True. I've always felt that the RNT's are where you can mess up after the first dive-which is where the conservative calculations should be made. Of course, the NDL's can effect the TBT when you add in the RNT so they are interconnected. :smiley20: