Teaching Dive Tables (including Nitrox)

[Edward3c]

Wow! I'm already a troll.
But I just wanted to point out that you can't dive without understanding the dangers that await you. And one of them is the DСS.
And the safe depth of 40 meters is not so safe - it's all a question of time. Therefore, a recreational diver should also know about tables, and not leave this issue to the discretion of the instructor.

Therefore I should be in a chamber having done 2 x 20m +60min dives yesterday.

Dive 1 with required 2min deco @ 6m according to the tables.
Dive 2 was off the tables, which end at 37min for the 20m dive requiring 18min @ 6min.

Yet my computer never got lower that 25min remaining before a stop would be required.

 

[Valeriy_Kulaha]

Therefore I should be in a chamber having done 2 x 20m +60min dives yesterday.

Dive 1 with required 2min deco @ 6m according to the tables.
Dive 2 was off the tables, which end at 37min for the 20m dive requiring 18min @ 6min.

Yet my computer never got lower that 25min remaining before a stop would be required.

It seems to me that you are not calculating the tables quite correctly! And also - check the computer in the calculations. It does not know, for example, about the beer you drank in the evening, your temperature and the stormy night. It just stupidly puts you under the banner without realizing that you have lost your legs!

 

[Valeriy_Kulaha]

Tables do exist separately from physiology.

When you teach scuba, you teach physiology, and you teach decompression theory.

Then you teach how to manage decompression. It could be with tables. It could be with computers. It could be with both.

In many cases, instructors taught decompression theory along with how to use tables, so many people mistakenly believe that that are the same thing, but they are not. Mark Powell wrote an entire book (Deco for Divers) on decompression theory without once teaching how to use tables for NDL dives.

The instructor cannot develop his own tables - he does not have his own hospital and observations. Therefore, I do not consider his tables authoritative - this is a compilation of Switzerland and US Navy.

 

[Edward3c]

It seems to me that you are not calculating the tables quite correctly! And also - check the computer in the calculations. It does not know, for example, about the beer you drank in the evening, your temperature and the stormy night. It just stupidly puts you under the banner without realizing that you have lost your legs!

You are unlikely to know the tables I use. Your opinion means nothing to me.

Tables, like the computer algorithm, are based on 'best guess' from tests on animals and super fit military personnel.

 

[tursiops]

@Valeriy_Kulaha How do you do a multilevel dive using your tables?

 

[GreggS]

It seems to me that you are not calculating the tables quite correctly! And also - check the computer in the calculations. It does not know, for example, about the beer you drank in the evening, your temperature and the stormy night. It just stupidly puts you under the banner without realizing that you have lost your legs!

Although this is a bunch of nonsense, your tables know none of this, either. And if you've been guzzling beer, but insist on going diving, you are more than likely to miscalculate using your tables anyway. So a computer would still be the best way to go.

 

[Jai Bar]

I don't know why people make such a fuss about the tables. There is no voodoo involved: the tables are based on the same algorithms used in the diving computers. One can consider them as a particular case, a printout from a computer for square profiles.

Does that make them more dangerous or the computer safer? Not necessarily..

 

[boulderjohn]

The instructor cannot develop his own tables - he does not have his own hospital and observations. Therefore, I do not consider his tables authoritative - this is a compilation of Switzerland and US Navy.

Who said anything about an instructor developing his own tables?

Whose tables do you not consider authoritative?

What is a compilation of Switzerland and the US Navy?

 

[boulderjohn]

And the safe depth of 40 meters is not so safe - it's all a question of time. Therefore, a recreational diver should also know about tables, and not leave this issue to the discretion of the instructor.

Who said anything about 40 meters being safe?

Of course it is a matter of time--the is one of the first lessons taught when students learn decompression theory.

Again, why does a diver need to know about tables? Why can't you teach how nitrogen pressure increases during a dive, how it leaves the body upon ascent, and how a computer measures it and provides guidance?

Finally, what issue is being left to the discretion of the instructor?

 

[wedivebc]

The instructor cannot develop his own tables - he does not have his own hospital and observations. Therefore, I do not consider his tables authoritative - this is a compilation of Switzerland and US Navy.

A dive computer is just another way of presenting the same information found in the dive tables. They are mostly derived from a neo-haldane multi compartment formula that represents a theoretical representation of what happens in out bodies. Your argument that a diver must know tables in order to avoid death is ridiculous.