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MicahEW
02-11-2008, 09:01
I took part one of my scuba cert this past weekend. I was advised to learn dive tables in addition to computers and the PADI dive calculator. There are many different types of tables. I have heard that the ones the we got from PADI with our class books are really conservative and that the NAVY dive tables are more on the edge. Is this true?

NitroWill
02-11-2008, 09:04
I would not say they are *really* conservative but they are more conservative then the navy tables. Navy tables were meant for 18-24 males in top condition - which obviously is not true with a large percentage of divers today - hence more conservatism. Between certification agencies there isn't too much difference..

MicahEW
02-11-2008, 09:17
are there any safe ways for me to test the navy tables?

fisheater
02-11-2008, 09:21
are there any safe ways for me to test the navy tables?

No one should try to "test" any dive table (or computer), if you mean to try to find out how close you can go to the maximums before encountering DCS.

Such testing involves many layers of safety and sophisticated medicial monitoring. It's not a one man job.

You were taught to dive WITHIN the limits of tables/computers, not at the edge of them. At least, I hope that that is what they taught you.

terrillja
02-11-2008, 09:22
are there any safe ways for me to test the navy tables?
Define test. Do you want to get a copy of the tables and dive them, or what do you mean by test?

MicahEW
02-11-2008, 09:25
yes I didnt mean test the limits. I just want to see if I can handle the navy dive table instead of the conservative PADI table.






are there any safe ways for me to test the navy tables?
Define test. Do you want to get a copy of the tables and dive them, or what do you mean by test?

terrillja
02-11-2008, 09:31
yes I didnt mean test the limits. I just want to see if I can handle the navy dive table instead of the conservative PADI table.






are there any safe ways for me to test the navy tables?
Define test. Do you want to get a copy of the tables and dive them, or what do you mean by test?


Well here is the navy no-deco table:
Tauchen mit Jochen van Waasen - Tauchtabellen - US Navy No-Decompression Table - 0-300m (http://www.vanwaasen.de/TABLES/USNAVY/USNAVY-NE.HTML)

Hopefully this is what you are looking for. The site also has tons of other dive tables FWIW.

Foo2
02-11-2008, 09:33
yes I didnt mean test the limits. I just want to see if I can handle the navy dive table instead of the conservative PADI table.

I'm sure you could find the navy dive table....that being said, I would recomend that you stick to your tables that you are trained with. In my book when it comes to DCS it just isn't worth the risk. :smiley2:

Chad
02-11-2008, 09:50
If you are trying to increase your bottom time I would suggest getting a computer. Since most people do not dive a completely square profile a computer will recalculate your NDL time as you change depth. This can significantly increase your NDL if you are diving a more sawtooth or gradually ascending profile.

ScubaToys Larry
02-11-2008, 09:52
You can compare the tables by downloading the Computerized Table Tutor and running dives on 9 different table formats: Table Tutor, Education, ScubaToys, Table Tutor (http://www.scubatoys.com/store/detail.asp?PRODUCT_ID=TableTutor)

DarinMartell
02-11-2008, 09:59
You can compare the tables by downloading the Computerized Table Tutor and running dives on 9 different table formats: Table Tutor, Education, ScubaToys, Table Tutor (http://www.scubatoys.com/store/detail.asp?PRODUCT_ID=TableTutor)

Very vool, before I download the tutor does anyone know if any the nine covers computers? Specifically Oceanic...

MicahEW
02-11-2008, 09:59
ok let me try to clarify a little bit. I have a set of navy dive tables that I want to use but have been told that they are designed for younger ppl built like an ox. I am wondering how I can determine if diving with them is right for me?? I dont have a computer yettttt but it will be a sure thing for me later.

KGNickl
02-11-2008, 10:48
You can compare the tables by downloading the Computerized Table Tutor and running dives on 9 different table formats: Table Tutor, Education, ScubaToys, Table Tutor (http://www.scubatoys.com/store/detail.asp?PRODUCT_ID=TableTutor)
Sounds cool! I'm going to download that when I get home and send you a PM to get the unlock code.

navyhmc
02-11-2008, 10:51
If you don't have a computer, use the tables that you were taught. As others have said, the navy tables are intended for healthy young adults is very good physical shape. Even at that, there are still DCS incidents within the navy when those same table are followed exactly.

And yes, the current tables are very conservative and should still be followed. Don't push them, the extra 2-5 minutes of down time is not worth the increased risk of a life altering episode of DCS. Death is also life atlering.

The tables from many years ago are a bit more liberal (60' was 60 minutes vs. current 55 min) but there were more folks that pushed it to the limit, did no safety stop and took a hit.

But if you want to know is the navy tables are right for you, can you:

Swim 500 yds in 8 minutes or less?
Swim 50 yds underwater in one breath?
Run 1 1/2 miles in 12 minutes or less?
Do 80 sit-ups/cruches in 2 minutes?
Do 80 push ups in 2 minutes?
Do 15 chin ups?
Swim one mile in 45 minutes of less?
Able to run 5 miles in one hour nonstop?

If the answer to all of these is "yes" then you are fit to use the navy tables. But before you use them, I would also suggest undergoing a navy dive physical.

MILPERSMAN 1220-100 - EXHIBIT 8 (http://buperscd.technology.navy.mil/bup_updt/508/milpers/1220-100%20Exhibit%208.htm)

Manual of the Medical Department (NAVMED P-117): Chapter 15: Medical Examinations (http://www.brooksidepress.org/Products/OperationalMedicine/DATA/operationalmed/Manuals/ManMed15/66Diving.html)

KGNickl
02-11-2008, 10:52
ok let me try to clarify a little bit. I have a set of navy dive tables that I want to use but have been told that they are designed for younger ppl built like an ox. I am wondering how I can determine if diving with them is right for me?? I dont have a computer yettttt but it will be a sure thing for me later.
They are designed for young men. Most likely 150-200 lbs and in peak physical fitness. Plus i'm sure the Navy does various test before training a diver as far as fitness levels go. Plus they are not designed for recreational diving. Unless you are experienced and know what your doing I would just avoid them.

I would just stay w/ the PADI recreational dive tables (or similar). These table would not have been designed if the Navy tables where ideal for the average recreational diver.

navyhmc
02-11-2008, 10:56
And let me reiterate: Get a Recreational dive table of your training (PADI/NAUI/SSI, etc) Practice with it, plan with it and dive your plan until you get your compter. I hear Scuba Toys has a great deal on an Oceanic GEO.

Taking a DCS hit is not worth 5 minutes of down time! EVER!!!

ETA: we won't mention that the navy usually has on site medical staff and recompression chambers. And the ORM (operational risk management) has an acceptable level of risk that is not accpetable in the civilian world.

USE AND FOLLOW the RPD, the Wheel or the e-RDP if you're PADI certified.

in_cavediver
02-11-2008, 11:17
ok let me try to clarify a little bit. I have a set of navy dive tables that I want to use but have been told that they are designed for younger ppl built like an ox. I am wondering how I can determine if diving with them is right for me?? I dont have a computer yettttt but it will be a sure thing for me later.

Micah,

Here is a different strategy. One, realize you don't want to push ANY model because the results could be fatal. Now, if you want to extend bottom times, simply learn to do it right. I personally use the Buehlman based tables/models which are a bit more conservitive than the PADI DSAT model. I dive nitrox which extends bottom times while remaining in the NDL. I also have done advanced nitrox/trimix so instead of staying within the NDL, I can plan my own bottom time and any requisite deco. I get the dive time I want and I stay safe.

This is the right way to 'push NDLs'. There is nothing macho about the Navy tables. They are old, out of date and nice historical bits but there are FAR better options out today, especially for rec divers.

texdiveguy
02-11-2008, 11:51
I took part one of my scuba cert this past weekend. I was advised to learn dive tables in addition to computers and the PADI dive calculator. There are many different types of tables. I have heard that the ones the we got from PADI with our class books are really conservative and that the NAVY dive tables are more on the edge. Is this true?

From my stance on this question....the PADI tables are proven safe and 'fit' the profile of many divers....DSAT has done a good job formating them. I have never dove Navy tables and never will....for me there are better options on the market that match 'me' better. I would suggest you stick to your PADI tables and enjoy diving....at some point you mention that a dive computer is in your plans...that is great and a cool tool to learn and use. Be safe dude!

navyhmc
02-11-2008, 11:59
Oh sure in_cavcediver...bring that there voodoo gas into the picture. :D

Actually, I didn't even think about suggesting Nitrox. good idea.

This from someone who also is nitrox cert. I guess I need ot use it more.

CompuDude
02-11-2008, 19:52
You can compare the tables by downloading the Computerized Table Tutor and running dives on 9 different table formats: Table Tutor, Education, ScubaToys, Table Tutor (http://www.scubatoys.com/store/detail.asp?PRODUCT_ID=TableTutor)

Very vool, before I download the tutor does anyone know if any the nine covers computers? Specifically Oceanic...

Computers don't use tables. Not in the way you mean, at least. Regardless, no, you would not be able to compare tables to any computers with the TableTutor software. Although even if you could it would be meaningless since computer profiles are never square and tables have to to be square (or, in the case of the Wheel, a modified jaggy-edged square)

DarinMartell
02-11-2008, 21:35
You can compare the tables by downloading the Computerized Table Tutor and running dives on 9 different table formats: Table Tutor, Education, ScubaToys, Table Tutor (http://www.scubatoys.com/store/detail.asp?PRODUCT_ID=TableTutor)

Very vool, before I download the tutor does anyone know if any the nine covers computers? Specifically Oceanic...

Computers don't use tables. Not in the way you mean, at least. Regardless, no, you would not be able to compare tables to any computers with the TableTutor software. Although even if you could it would be meaningless since computer profiles are never square and tables have to to be square (or, in the case of the Wheel, a modified jaggy-edged square)


Thanks, I was thinking I would like to compare my new veo to my Padi tables to see the basic differences for the dives I could do on the tables.

navyhmc
02-11-2008, 23:25
You can compare the tables by downloading the Computerized Table Tutor and running dives on 9 different table formats: Table Tutor, Education, ScubaToys, Table Tutor (http://www.scubatoys.com/store/detail.asp?PRODUCT_ID=TableTutor)

Very vool, before I download the tutor does anyone know if any the nine covers computers? Specifically Oceanic...

Computers don't use tables. Not in the way you mean, at least. Regardless, no, you would not be able to compare tables to any computers with the TableTutor software. Although even if you could it would be meaningless since computer profiles are never square and tables have to to be square (or, in the case of the Wheel, a modified jaggy-edged square)


Thanks, I was thinking I would like to compare my new veo to my Padi tables to see the basic differences for the dives I could do on the tables.

You'll find that the biggest advantage to a computer is that you don't have to calculate a square profile of a table or a stair-step type profile of PADI's The wheel with the plan of having a maximum depth for the various initial and subsequent depths. There are limitations to a computer and those are spelled out in your manual when you get one, read it well.

Case in point: Did a dive with max depth of 110' for 13 minutes with a slow ascent to 75' followed by a practice deco at 20' and 10' Had I followed the tables, it would have been a case of totally blowing the table and I surely should have been narced. However, since I was using a computer, I was still well within the NDL limits as shown on the nitrogen loading bar.

Keep in mind ,this is coming from a guy who has sworn off computers as a unneccessary expense for the past 30+ years. Okay, last 10-12 years. :D

MicahEW
02-12-2008, 08:01
You can compare the tables by downloading the Computerized Table Tutor and running dives on 9 different table formats: Table Tutor, Education, ScubaToys, Table Tutor (http://www.scubatoys.com/store/detail.asp?PRODUCT_ID=TableTutor)

Very vool, before I download the tutor does anyone know if any the nine covers computers? Specifically Oceanic...

Computers don't use tables. Not in the way you mean, at least. Regardless, no, you would not be able to compare tables to any computers with the TableTutor software. Although even if you could it would be meaningless since computer profiles are never square and tables have to to be square (or, in the case of the Wheel, a modified jaggy-edged square)


Thanks, I was thinking I would like to compare my new veo to my Padi tables to see the basic differences for the dives I could do on the tables.

You'll find that the biggest advantage to a computer is that you don't have to calculate a square profile of a table or a stair-step type profile of PADI's The wheel with the plan of having a maximum depth for the various initial and subsequent depths. There are limitations to a computer and those are spelled out in your manual when you get one, read it well.

Case in point: Did a dive with max depth of 110' for 13 minutes with a slow ascent to 75' followed by a practice deco at 20' and 10' Had I followed the tables, it would have been a case of totally blowing the table and I surely should have been narced. However, since I was using a computer, I was still well within the NDL limits as shown on the nitrogen loading bar.

Keep in mind ,this is coming from a guy who has sworn off computers as a unneccessary expense for the past 30+ years. Okay, last 10-12 years. :D

In this case was that the correct deco stops? Is what I was taught ( safety deco at 15') wrong????

terrillja
02-12-2008, 08:18
In this case was that the correct deco stops? Is what I was taught ( safety deco at 15') wrong????

You should still do deco at 15', but you can use your computer to check for nitrogen loading. If air permits you can do a longer deco stop if the nitrogen loading is a bit high.

MicahEW
02-12-2008, 08:22
You can compare the tables by downloading the Computerized Table Tutor and running dives on 9 different table formats: Table Tutor, Education, ScubaToys, Table Tutor (http://www.scubatoys.com/store/detail.asp?PRODUCT_ID=TableTutor)

Very vool, before I download the tutor does anyone know if any the nine covers computers? Specifically Oceanic...

Computers don't use tables. Not in the way you mean, at least. Regardless, no, you would not be able to compare tables to any computers with the TableTutor software. Although even if you could it would be meaningless since computer profiles are never square and tables have to to be square (or, in the case of the Wheel, a modified jaggy-edged square)


Thanks, I was thinking I would like to compare my new veo to my Padi tables to see the basic differences for the dives I could do on the tables.

You'll find that the biggest advantage to a computer is that you don't have to calculate a square profile of a table or a stair-step type profile of PADI's The wheel with the plan of having a maximum depth for the various initial and subsequent depths. There are limitations to a computer and those are spelled out in your manual when you get one, read it well.

Case in point: Did a dive with max depth of 110' for 13 minutes with a slow ascent to 75' followed by a practice deco at 20' and 10' Had I followed the tables, it would have been a case of totally blowing the table and I surely should have been narced. However, since I was using a computer, I was still well within the NDL limits as shown on the nitrogen loading bar.

Keep in mind ,this is coming from a guy who has sworn off computers as a unneccessary expense for the past 30+ years. Okay, last 10-12 years. :D

so these types of decos are benefits of a computer??

Kingpatzer
02-12-2008, 08:41
ok let me try to clarify a little bit. I have a set of navy dive tables that I want to use but have been told that they are designed for younger ppl built like an ox. I am wondering how I can determine if diving with them is right for me?? I dont have a computer yettttt but it will be a sure thing for me later.

Ok, here's my answer.

As you clearly don't understand enough about DCS, diving, table design, and decompression theory that you have to ask this question, the answer is that they are not right for you. You are a recreational diver, and should be diving on a recreational table.

Since you don't have a navy physical, on-site navy medical staff, or the knowledge of why such would be necessary, the answer is that they are not right for you. You are a recreational diver, and should be diving on a recreational table.

Want to extend your bottom time? Find a reef that has lots of fish and stuff to see at 25' and stay shallow. Your tank will be dry before you're out of NDL.

MicahEW
02-12-2008, 09:00
I know I just wanted to push it a little but still be safe. I know I changed the subj a little but let me see if I understand the above.

dive tables and dive comps can give you different decos? And the dive comp is the best way to go???

terrillja
02-12-2008, 09:05
I know I just wanted to push it a little but still be safe. I know I changed the subj a little but let me see if I understand the above.

dive tables and dive comps can give you different decos? And the dive comp is the best way to go???
Tables are designed for diving square profiles, descend to a set depth, stay at that depth, then go up. Computers can account for changes in depth, but computers use many different algorithms to calculate nitrogen loading. Honestly you probably won't push your NDL using an al80, but you could do it. Some computers will also go into a gauge mode or use another way to indicate that you have exceed your NDL, which is a good safety feature. I always watch my nitrogen loading on deep dives and have never gone past yellow on my veo180.

navyhmc
02-12-2008, 09:13
The practice deco stops were due to my buddy starting a Deep TEc course and he wanted the practice. I considered these dives as having a very long safety stop.

The fact of the matter is as a recreational diver, doing a dive that requires decompression stops is not smart, not wise and definitely not safe unless you've had the proper training to do deco.

A computer is a good way to safely extend your bottom time. However always and I mean always back up your computer with tables. While I've been diving for 30+ years, I'm fairly new to dive computers so I always have a back up plan and I practice that back up plan.

If you get a computer, remember that it can fail. The reliabiltiy is getting better, but still, technology can fail easier as it gets more complex. Recreational dive tables are more than your friend, they should be your constant companion while diving.

Still, the computer is a good piece of equipment. If you get one, learn all about it, all it's features, which features are pre-dive accessable, which are accessable during the dive, what is accessable after the dive. Be able to quickly and easily access the various screens and information formats and be damned sure you know exactly what it telling you when you look at it.

PlatypusMan
02-12-2008, 09:18
You can compare the tables by downloading the Computerized Table Tutor and running dives on 9 different table formats: Table Tutor, Education, ScubaToys, Table Tutor (http://www.scubatoys.com/store/detail.asp?PRODUCT_ID=TableTutor)

I've recommended this software to any new OW students I'm fortunate enough to be involved with--since I TA through ST, that's not too hard to do!

It's a great practice and refresher software, and for the price quoted at Larry's link above cheap at 10 times the price in terms of value. :smiley2:

PPM

Kingpatzer
02-12-2008, 10:19
dive tables and dive comps can give you different decos? And the dive comp is the best way to go???

All NDL and deco tables and algorithms are models based on observed data. They all give slightly different information based on observed data. All of them carry some risk of taking a hit even if you follow them precisely. More aggressive tables and algorithms are more aggressive precisely because they increase the risk of taking a hit -- and are thus generally unsuited for non-professional use precisely because available support requirements for people taking hits are less commonly met in recreational settings.

The inherent risk of taking a hit is why one should never push any table or algorithm. You don't want to be on the edge of acceptable limits, you want to be well within your limits -- at least until you understand the risks you are taking to a much higher level.

If you are recreationally diving tables or computer algorithms, you are not looking at decompression tables, but No Decompression Limits (NDLs). They are related, but not entirely the same thing.

If you are looking at required decompression stops, then you're no longer talking about purely recreational diving, but technical diving, which comes with significantly more training and inherent risk. And therefore requires much more experience to engage in safely.

MicahEW
02-12-2008, 10:45
dive tables and dive comps can give you different decos? And the dive comp is the best way to go???

All NDL and deco tables and algorithms are models based on observed data. They all give slightly different information based on observed data. All of them carry some risk of taking a hit even if you follow them precisely. More aggressive tables and algorithms are more aggressive precisely because they increase the risk of taking a hit -- and are thus generally unsuited for non-professional use precisely because available support requirements for people taking hits are less commonly met in recreational settings.

The inherent risk of taking a hit is why one should never push any table or algorithm. You don't want to be on the edge of acceptable limits, you want to be well within your limits -- at least until you understand the risks you are taking to a much higher level.

If you are recreationally diving tables or computer algorithms, you are not looking at decompression tables, but No Decompression Limits (NDLs). They are related, but not entirely the same thing.

If you are looking at required decompression stops, then you're no longer talking about purely recreational diving, but technical diving, which comes with significantly more training and inherent risk. And therefore requires much more experience to engage in safely.


well looks like I have more training and learning to do. I want to do the deep diving. Just like some like to go diving when its sleeting and is 6 degrees.

ianr33
02-12-2008, 10:50
well looks like I have more training and learning to do hehe. I want to do the deep diving. Just like some like to go diving when its sleeting and is 6 degrees. I am becoming addicted to the risk.

You should give up diving and take up something like Base Jumping or Extreme Skiing if you are in it for the adrenaline.

IMHO

MicahEW
02-12-2008, 11:00
ok, so I edited to keep from sounding like im crazy. sorry for the brief ID10T err.

ianr33
02-12-2008, 11:10
ok, so I edited to keep from sounding like im crazy. sorry for the brief ID10T err.

Too late. I quoted it and preserved it for all eternity :smiley36:

Seriously though,diving is not about adrenaline or risk,it is about managing risk.

What some may consider crazy (deep trimix dives,cave dives,diving in water colder than 55 degrees etc ) is not THAT dangerous if you know what you are doing. If you dont have a clue then you will probably kill yourself.

As to your original question,diving to the Navy tables is a really,really,really bad idea.As has been pointed out they are designed for Navy divers who will have a decompression chamber ON SITE.Most of us do not have that luxury.
I think PADI's NDL for 100 feet on air is 20 minutes? Navy Tables is 25 IIRC. If I want to dive to that depth for longer than 20 minutes I will do so by following appropriate deco stops from something like V-Planner,NOT navy tables.

If you want to dive deeper and longer take your time,get some experience and training and do it properly. Please !

MicahEW
02-12-2008, 11:18
ok you have a deal i wont do it without training first.

in_cavediver
02-12-2008, 12:06
I just want to point out a few things because I can fit in the 'High risk diving' category by some.

First, all diving contains some risk. We learn skills and techniques to manage that risk but we never eliminate it. Diving is also relatively safe. The number of incidents are pretty low overall but if you look at what those are, almost all have divers doing things well beyond their training and experience. Don't become a statistic.

Talking about depth and its dangers. I like to tell a lot of newer divers that the most dangerous thing about deep diving for them is the fact they don't know enough to even identify all the risks that it brings. Every increase in depth will increase you gas consumption rate, decrease you mental facilities (narcosis) and take you just that much farther from the surface. Many techniques taught in the OW class just aren't appropriate at deeper depths. Do a search on max depth for CESA or Rock Bottom gas planning to see what I mean.

With deco theory, we have learned much over the years about how it applies to individuals but remember, its still theory and it may not apply to you on any given day or dive. If you don't have a strong grasp of deco theory, you really don't have any business considering a planned deco dive. (and I am glad you said you wouldn't!)

Everything I mentioned can be learned. Some really needs to be via formal classes not through experience though. None of it is rocket science but ask any tec diver about their first time doing some skills and you'll get a good story about how they screwed up. You want to make sure the first time you do this stuff, its not for real and you life hang in the balance.

(stepping down from the soapbox now)

DarinMartell
02-12-2008, 14:32
This thread has developed some really good info for us Nubes. It could have easily turned into everyone jumping on the OP for thinking about using Navy tables, instead I have picked up a-lot of food for thought. Thank you!

captain
02-12-2008, 23:40
I started with the Navy tables and used them for 26 years until the first real dive computer, the Edge came out in 1983. I still use the Navy tables as back up for a computer failure.
From the beginning of the Navy tables the normal accent rate was 60 fpm, it was changed to 30 fpm I believe sometime in the late 80's.
All tables and all computers are not and never will be able to prevent all DCS hits in all people. I believe the Navy tables are more conservative on repetive dives than the PADI tables but not on single dives. I frankly don't buy into the Navy tables are just for 18 to 25 year old supermen. Generally 45 is the age limit for Navy divers but this is based on physical condition rather that actual age.
Most all certification organzinations used the Navy tables in their courses until they developed or adopted other tables. When I began diving in 1957 and when I was YMCA certified in 1970 the Navy tables were all we had.

in_cavediver
02-13-2008, 05:28
All tables and all computers are not and never will be able to prevent all DCS hits in all people. I believe the Navy tables are more conservative on repetive dives than the PADI tables but not on single dives. I frankly don't buy into the Navy tables are just for 18 to 25 year old supermen. Generally 45 is the age limit for Navy divers but this is based on physical condition rather that actual age.


That little tidbit about repetitive dive conservitism is somewhat true but is based on the fact Navy tables are true decompression tables using a tissue model. The Buelmann tables are more conservitive that the Navy tables for the same reason. PADI/DSAT's RDP was developed specifically for No stop diving and as such didn't have to worry about loading/offgassing in some long compartments because withing the scope of NDL diving, its not possible for those to hit a controlling factor. It was one of the 'Breakthroughs' of the RDP at the time. Something designed for how rec divers dive.

MicahEW
02-13-2008, 08:37
hey Darin you are right. This thread has been great for the newbies.

and to captain and in_cavediver. your posts have been great and have helped tremendously. Thanks to all.................

Rockhound76
02-19-2008, 06:52
The idea that Navy tables are designed only for "24yr. old athletes in superb condition" or that they have some loosely high acceptable rate of DCS hits when followed are part of diving mythology.

The Navy tables are less conservative on single dives to depth, but pretty conservative on multiple dives. They are not, however, based on sophisticated tissue models, but on fairly simple ones, derived from empirical data.

You "might" get bent on any table or on any computer, if you push the limits. If you dive conservatively, you will be "statistically" safe on all of them.

I've been diving Navy tables for 31 years (when I'm not on a computer). I'm certainly not a young stud Navy diver, but I also don't dive on the edge.

When I started diving on these tables, the safe ascent was 60' a minute (chase the little bubbles), no stops. Over the years, I added in and planned for safety stops on all of my dives below 30'. Later, the ascent rate was halved on the shallow part of the ascent. All of this added a margin of safety.

Now that my son is diving with me, I'll either go over to his NAUI tables or we'll both move over to RGBM as backup to our computers. My main concern is that we both dive the same models, whether computer or table, but only to standardize our diving practice and allow him to dive the system he was taught (and has the tables for), and not because the Navy tables are inherently unsafe.

in_cavediver
02-19-2008, 16:43
The idea that Navy tables are designed only for "24yr. old athletes in superb condition" or that they have some loosely high acceptable rate of DCS hits when followed are part of diving mythology.

Well, this may be overstated but the fact remains that data used to construct, evaluate and evolve the Navy tables came from Navy divers. This does have a very strong selective pressure for younger males in good physical fitness. To claim the standard run of mill rec diver today fits that mold is questionable.


You "might" get bent on any table or on any computer, if you push the limits. If you dive conservatively, you will be "statistically" safe on all of them.

I've been diving Navy tables for 31 years (when I'm not on a computer). I'm certainly not a young stud Navy diver, but I also don't dive on the edge.

This is the very crux of the statement. You have never pushed the edges of the Navy tables which means you likely haven't pushed Padi, NAUI, RGBM or Buelmann tables either. All very good practice for rec divers and yes, you are likely just as safe.

The OP on the other hand wanted to push the edge (and possibly go past it) on Padi tables and was looking at the Navy tables to do this. This is where deco theory really is involved and you will see significant differences in the tables. Each diver who does these dives will have models they like and work for them and their bodies.

I don't know a single tec diver who uses the Navy tables. I know lots who use RGBM, Beuhlmann w/gradient factors and Buelhmann w/pyle stops. There is a reason to this pattern.

ScubaToys Larry
02-19-2008, 18:22
Just on another note... I know there were some questions about how does the veo stack up against the padi or navy tables, and actually Oceanic licensed the algorithms from DSAT but them modified them slightly. Now if you look at a 60 foot dive, the navy tables will say 60 minutes allowable dive time, the padi tables 55... the veo computer will say 57. But some of the numbers on the padi tables are rounded a bit.

But I think the message everyone gave here is good... there is no sense in pushing the limits of any table or any computer, and when it comes down to it, more people have gotten bent within table limits than outside them. The major causes being too fast of ascents and dehydration.

There is no real way to see what will get you bent - without getting bent, and then, you probably will not be able to dive for a long time. And depending on the degree of the bends case - maybe not walk... think, eat... etc.

It would be like going faster and faster around a curve with your car to see how fast can you take the turn before your car crashes into the tree... great experiment... but once you have the answer - it's over.

Now to determine table limits they use in recreational diving, they did do some testing using compression chambers to simulate dives, and using sophisticated doppler bubble detection devices, they can listen for the formation of micro bubbles in the body, but then run through decompression systems in the chamber to make sure no one got injured.

But through this testing, they also learned that what might be pushing you into a bends case one day, may not the next...

So really no point in trying to do something that is so potentially dangerous.

The reason to dive is not to "push limits" but to spend time diving, so I'd suggest after you get certified, also look at nitrox so you can dive for longer times without risking getting bent.

Enjoy!

cummings66
02-19-2008, 22:15
Larry, that is the best post I've seen yet on the topic. They maybe not walk, think, eat bit should scare anybody who's remotely thinking of pushing the limits just to find out how far they can take it.

Diving is serious stuff, we have fun with it but dang, why on Earth would anybody be willing to risk permanent disability in order to stay down a few more minutes.

I liked your other analogy about the glock and the kids, same principle here.