Teaching Dive Tables (including Nitrox)

[The Chairman]

and I can't begin to estimate how often I have taught tables.

Nor I. I was asked at times to 'dive-splain' them when other instructors hit a brick wall with a student or two, so I was pretty good at it too. Tables were always a source of consternation, and a bit of black magic mixed into deco theory. I found using visual aids, such as soda bottles to be able to get the concepts across a lot more effective. I even had a write-up in the NAUI journal on that, the first year I was an instructor. That was pretty cool.

 

[Blackcrusader]

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.

Sure you can people do it all the time. Very rarely do they get a DCS hit or die.

 

[Blackcrusader]

Wow! I'm already a troll.
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,

What tables would you have used for this multilevel NDL dive.

 

[boulderjohn]

The world is changeable and no computer can calculate what awaits me around the bend in the road!

Are you arguing that tables do know what awaits you around the bend in the road?

Here is a story of two friends who got mildly bent on a technical dive (not a really serious one). They were not using computers for the dive--they were following a form of table diving called ratio deco. When they got bent, they later went to a computer they had used in gauge mode during the dive to see the dive profile. Here is what they learned.

1. The had spent much more time than they had realized deeper than their supposed maximum depth. They knew they had "strayed" below it a few times, but they learned they had done much more then stray below it a few times.
2. They had taken much more time than they realized getting to their first decompression stop, so they had added greatly to their bottom time without realizing it.
3. They thought they had followed their ascent plan perfectly, but the computer profile showed they had miscounted one of their stops and left too early.

So these people got bent because they had not followed their dive plan as perfectly as they had thought--it was an unpredicted bend in their road. They did not know it had happened, and the tables didn't know it. The computer knew it, but they weren't following the computer. If they had been using the computer, the computer would have known things had not gone according to plan, and it would have adjusted their ascent accordingly.

 

[tursiops]

My wife had a nice way of teaching dive tables that worked really well for a lot of people. She described the tables like a credit card account: you went shopping, and the deeper you went and the longer you stayed, the more your CC account grew. And there was a charging limit....the NDL. But you had to pay it off....a little bit at the end of the dive, by going up slowly, and then some more with time spent waiting at the surface for the next dive. But if you dived again (went shopping again) the same day, you still owed money on your card and so your spending limit was reduced.

 

[Allen-1]

My wife had a nice way of teaching dive tables that worked really well for a lot of people. She described the tables like a credit card account: you went shopping, and the deeper you went and the longer you stayed, the more your CC account grew. And there was a charging limit....the NDL. But you had to pay it off....a little bit at the end of the dive, by going up slowly, and then some more with time spent waiting at the surface for the next dive. But if you dived again (went shopping again) the same day, you still owed money on your card and so your spending limit was reduced.

stolen <cough> copied

Into my notes - thanks.

 

[rongoodman]

That's a pretty good explanation of how inert gases build up and are released but it really has nothing to do with tracking the process with tables as opposed to a DC.

 

[Valeriy_Kulaha]

Are you arguing that tables do know what awaits you around the bend in the road?

Here is a story of two friends who got mildly bent on a technical dive (not a really serious one). They were not using computers for the dive--they were following a form of table diving called ratio deco. When they got bent, they later went to a computer they had used in gauge mode during the dive to see the dive profile. Here is what they learned.

1. The had spent much more time than they had realized deeper than their supposed maximum depth. They knew they had "strayed" below it a few times, but they learned they had done much more then stray below it a few times.
2. They had taken much more time than they realized getting to their first decompression stop, so they had added greatly to their bottom time without realizing it.
3. They thought they had followed their ascent plan perfectly, but the computer profile showed they had miscounted one of their stops and left too early.

So these people got bent because they had not followed their dive plan as perfectly as they had thought--it was an unpredicted bend in their road. They did not know it had happened, and the tables didn't know it. The computer knew it, but they weren't following the computer. If they had been using the computer, the computer would have known things had not gone according to plan, and it would have adjusted their ascent accordingly.

I have the impression that you do not understand what I am writing about. Maybe my English is bad?
That is why I want to clarify something
1. Tables and computers cannot know or predict anything - they are simply created to HELP you create an algorithm for your immersion.
2. The computer is an excellent assistant and greatly facilitates immersion, but you cannot plan a immersion created the day before and saved in your own head. The manufacturer of the best computers, Schervater, warns that:

You should always control your dive and the situation.
And the case you described and the rest of the same I mentioned in my signature "Divers are divided into old and brave"

 

[Edward3c]

I have the impression that you do not understand what I am writing about. Maybe my English is bad?

Nothing to do with your English. You don’t accept there are alternative views.

 

[DiveLikeAMuppet]

2. The computer is an excellent assistant and greatly facilitates immersion, but you cannot plan an immersion created the day before and saved in your own head. The manufacturer of the best computers, Schervater, warns that:
You should always control your dive and the situation.
And the case you described and the rest of the same I mentioned in my signature "Divers are divided into old and brave"

So tables are wrong, computers are wrong. How do YOU actually control your dive?