Which tables should you believe?

[Diver0001]

....snip....
If I check a 34 min dive to 19 meters on the slate the answer is group O - on the wheel it's group P (The official PADI answer was group P using a wheel). Which one is therefore correct?

The answer is both and neither.

There a many different tables out there but what are they really telling you? What does a computer tell you? What really happens under water? What does the NDL really mean?

R..

 

[Diver0001]

All I dare say, to answer you question, is that I have personally tested the DCIEM tables to unspeakable depths.

LOL - ....a little polite coughing.... Right on Indigo...Give it to them shaken but not stirred ..... LOL. Blue....Indigo Blue

For a minute there I was almost convinced that you could drive at "unspeakable" speeds, make love for "unspeakable" lengths of time and fight giants with "unspeakable" strength too.... LOL

I have found them to be truly conservative.

Of course they are. They're Canadian. We do nothing to the edge.....alas we are a boring--albeit intelligent, creative, inventive, intuitive, articulate and humble--but boring.....

I do not agree with PADI's mantra that diving 4 and 5 dives in a day is safe. That is what their tables are based on. Sorry.

Is this PADI's mantra? Holy cow....let's phone head office right now and inform them. I'm sure they'll want to know.....

Blue....IndigoBlue.

R..

 

[Mako Mark]

Commercial divers normally wear hard hats.

I always wondered how they attach snorkles to their hard hats???

 

[Diver0001]

I always wondered how they attach snorkles to their hard hats???

They tuck it under the longhose....

R..

 

[MikeFerrara]

I wouldn't go that far... I'd be lying if I said I don't massage the tables based on lots of things - like those Mike mentions - but to say the model is meaningless is a bit further than I'm willing to go. I always have tables as a baseline from which to make decompression decisions (including so-called "no decompression" dives, which most of mine are) for my little pea brain needs a "jumping off" point.
Rick

I didn't mean to say that the table was meaningless exactly...only the accuracy and precision. The fine line that some divers seem to be looking for either doesn;t exist or the table/computer can't find it exactly.

I too use a table (actually software) as a baseline. I do it with great precision though of course.

The one pressure group difference between the table RDP and the weel that Kim mentions is completely meaningless.

 

[zboss]

No algorithm is more correct than another since it is just a mathmatical simulation of what happens in the average human tissue. Your body will be somewhat different.
I defer to what UP said:

Why can't you enter you height/weight into the computer which in turn would use your BMI in the algorithm? There are probably a lot of user entry factors that could increase the credibility of various computers but would take forever to do using a table.

Just like when computers started out replacing typewriters, tehy didn't do too much that a typewriter did, but now - you can include automatic graphs and pictures etc... with little extra work. The tools (dive computers) will continue to get better and the old tables will be as common as that old IBM typewriter.

 

[Mako Mark]

And made unspeakable errors.

I do not agree with PADI's mantra that diving 4 and 5 dives in a day is safe. That is what their tables are based on. Sorry.
.

PADI follows the DAN recomendations of no more than three dives per day, and no more than three or four consecutive days of diving in a row.

I thought that DCIEM was basically the canadian navy (Defense and Civil Institute of Environmental Medicine), and that they were tested on navy divers, and unless you are a navy diver, then these tables exclude you from their demographic.

Try this link it has a good summary.

http://watch.citizen.co.jp/cyber/qa/eng/ans/dciem_e.htm

OTOH, do you really think that they would test and publish these tables based soley on hyperbaric chamber dives because the water is a little cold??

gimme a break.

The answer to the initial question is:

DONT TRUST ANY TABLES, THEY ARE ALL THEORETICAL.

(except for Uncle Pugs 120 rule which is based on experience)

 

[Diver0001]

....snip....

I thought that DCIEM was basically the canadian navy (Defense and Civil Institute of Environmental Medicine), and that they were tested on navy divers, and unless you are a navy diver, then these tables exclude you from their demographic.

Maybe but off the top of my head it shows shorter NDL's across the board than DSAT.

R..

 

[gj62]

The answer to the initial question is:

DONT TRUST ANY TABLES, THEY ARE ALL THEORETICAL.

Actually, I believe most of the tables were developed by actual testing - so they are basically the opposite of theoretical, they are imperical. Of course, that doesn't really make them an better (and may actually make them worse, since the test subjects may not behave like you at all).

Regarding tables based upon BMI - it isn't so much that using or programming the algorithm would be difficult - it is that developing the tables/algo would be very difficult.

As many have said, they are not a precise tool, and a pressure group one way or the other is of little meaning EXCEPT when you are being tested on your ability to use the table - then being off by a pressure group would show that you did not use the table correctly. Instead of getting DCS, you get F(lunked).

 

[Rick Inman]

(except for Uncle Pugs 120 rule which is based on experience)

See! Keep repeating it long enough and they'll think you invented it!