Max. depth, average depth, computers & tables

[Arnaud]

I've been wondering for a while about this one. I always start a dive at the greatest depth, slowly ascending afterwards. Just like in the book. However, It happened several times that I would find myself at the beginning of the dive at 70 or 80 feet for just a couple of minutes, didn't like what I saw, and actually spend most of the dive in the 30-45 feet range.

After each dive, I always double check my computer (Suunto) and compare the results with the tables, as to have a sense of what I can do and not do on the following dive (same day).

I don't use the wheel. It was not part of any certifications I did.

With a regular table, you're supposed to use your maximum depth to make all the calculations. Yet, I can be spending most of my bottom time at a much shallower depth (which allows for more air time and more no deco time). If I just stick to the tables, the third dive of the day is often a no-no, or a very short one. Obviously, my computer gives me a different story since it takes into account actual depths.

My questions are: is there any sense to use the average depth (calculated by the computer for each dive) with the tables? Should I just forget about the tables with this type of dive profile? Should I learn the wheel?

 

[jonnythan]

Apparently Pug has some ultra cool secrets on how to dive to the limits of no ceiling without tables. He tends to mention repetetive dives he's done with no tables and no computer....

To the best of my knowledge, he has never stated what these techniques were (other than a couple rules of thumb for remembering a basic first-dive table), or even where to obtain or learn them.

IMO, you should use your computer to make and plan dives, but keep up with your regular tables. Should your computer break, continue planning with tables if they allow you to make a reasonable dive... and if not, you're done for the day.

 

[Arnaud]

Well, I hope UP will find his way to this thread. But, what about using the average depth instead of the maximum depth with the table?

 

[JeffG]

Check out this post.

http://www.scubaboard.com/showthread.php?s=&threadid=7840

Now UP doesn't go into the actuals, but you can figure it out (I did). And I think it is better to figure it out than have someone tell you (It will stick with you longer)


After doing the math, I now agree with UP that computers do "Rot the Brain" and it has changed the way I dive.

 

[Arnaud]

Well, the rotting effect of the computer is more than fairly treated on other threads. Let's not go there. If I understand this correctly, UP does use the average depth, rather than the max depth, doesn't he?

On a side note, that's the best disclaimer I've seen in a while...

 

[Uncle Pug]

1. I absolutely mean the disclaimers and warnings!

2. I dive EAN32 on all recreational dives <100' and therefore have a built in safety factor.

3. The time spent shallow is very important!

4. Take a GUE DIRf at the bare minimum or stick with your brain rotter.

 

[Walter]

Multilevel diving with tables is very easy, but I don't know of any agency that allows its instructors to teach it.

A computer is designed for multilevel diving. I'd follow the computer, although not blindly.

 

[jonnythan]

Walter once bubbled...
Multilevel diving with tables is very easy, but I don't know of any agency that allows its instructors to teach it.

A computer is designed for multilevel diving. I'd follow the computer, although not blindly.

How is it very easy? My tables give NDL's and RNT's assuming I surfaced at 30 fpm and did a 3 minute safety stop at 15'.

I'm not trying to be argumentative, just wondering what I missed.

 

[Arnaud]

There he is!

1. Dully noted for the warning.

2. I don't like going below 100 ft. Why EAN32 only? Is it just to stick to a particular mix so that some of your parameters are always the same?

3. Completely agreed, too.

4. What's a Dirf?

5. How do you feel about using the average depth of the previous dive when prepping the next dive with Padi's tables?

The profile I talked about in my initial post happens often to me, especially when reef diving. The point being that I find it hard to plan my actual depths (before hand, as in "planning") unless I really know well the site, so I'm looking for references when prepping my dives. That's the context of my question.

 

[Uncle Pug]

Arnaud once bubbled...
2. Why EAN32 only? Is it just to stick to a particular mix so that some of your parameters are always the same?

4. What's a Dirf?

5. How do you feel about using the average depth of the previous dive when prepping the next dive with Padi's tables?

2. yes.
4. the introductory class of GUE www.gue.com
5. I can't advise that. We do it differently.