Which tables should you believe?

[Kim]

PADI has basically 4 tables available for rec divers. A slate planner and a wheel are available in both imperial and metric versions. However there appear to be differences between them. Recently someone posted a problem from the DM's workbook and the range of different answers (several also from instructors!) was amazing. I have both slate and wheel from the metric versions. A simple thing like working out a pressure group already gave two different answers between slate and wheel.
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? Does this also happen on FSW tables?
I did notice somewhere else that PADI issued a recall for some tables a couple of years ago - does anyone know more about this?

 

[wedivebc]

PADI has basically 4 tables available for rec divers. A slate planner and a wheel are available in both imperial and metric versions. However there appear to be differences between them. Recently someone posted a problem from the DM's workbook and the range of different answers (several also from instructors!) was amazing. I have both slate and wheel from the metric versions. A simple thing like working out a pressure group already gave two different answers between slate and wheel.
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? Does this also happen on FSW tables?
I did notice somewhere else that PADI issued a recall for some tables a couple of years ago - does anyone know more about this?

Yes PADI recalled a table but it was for a minor printing error and had a misprint in the surface interval credit area.
As far as the difference between the wheel and the slate, they are based on the same table. It is just that the wheel has more depth graduations 5ft opposed to 10ft and id less prone to rounding errors.
The whole concept of decompression theory is just that, a theory. Every table is designed to get you out of the water with minimal risk. Some may be less minimal than others such as US Navy table may be more aggressive, whereas PADI table may allow you more bottom time with repetitive shorter dives.
My personal favorite, DCIEM but really (I can feel the daggers already) if one is better than the other is a hard question hard to answer.

cheers,

 

[alemaozinho]

buy a dive computer,they are the most accurate.You cant solve a table question with the wheel and vice verca,apples and oranges you know.The wheel was invented to calculate multilevel diving and is therefore more preciser as the rdp.peace

 

[Kim]

buy a dive computer,they are the most accurate.You cant solve a table question with the wheel and vice verca,apples and oranges you know.The wheel was invented to calculate multilevel diving and is therefore more preciser as the rdp.peace

I have a Suunto Vyper - yes it's great, but I still like the back up of table planning.

 

[Mojo Jojo]

I guess if in doubt, I would dive the more conservative result I got on the table or
the wheel

 

[jagfish]

Kim
I think I know what you are talking about. If you calculate a dive or series of dives with both the imperial and metric PADI charts (but same version, table or wheel), you can sometimes arrive at a different pressure group.

I had attributed this to how they are sliced in terms of depth. For ease, they were both sliced into neat, whole numbers. If the imperial and metric versions were exact equivalents in terms of depth, there would have to be some pretty messy looking (and unwieldy) numbers on one version or the other.

These minor differences in depth between the two tables is what I have attributed the occasional differences to, but I could be wrong.

JAG

 

[IndigoBlue]

In my opinion, the Canadian DCIEM dive tables are the best tables on this earth, for all air or equivalent-air nitrox diving. You can probably surf the web for a set. Or you can get them out of one of TDI's tech manuals.

Dr. BRW has new tables out for trimix deco diving. Based on the amount of research that went into them, they are probably the best tables for trimix diving to a max depth of 350 ft. But that is a different story.

 

[Mojo Jojo]

What makes the DCIEM so good, Indigo Blue? I use PADI.

 

[IndigoBlue]

What makes the DCIEM so good, Indigo Blue? I use PADI.

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

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.

If you keep your depth shallower than 50 feet, and give yourself long surface intervals, you probably do not need any dive tables. But if you do need dive tables, truly need them, then I would recommend the Canadians' DCIEMs.

 

[Uncle Pug]

If you stop and think about all the differences not only in tables but in computer generated profiles, especially those that allow user input of conservation to be used... precision in output begins to look like a fools game.

Thinkaboutit.