Nitrox tables going too?

[Brendon]

Use the table, don't use the tables... Buy computer don't buy a computer. Well I did buy a computer, several in fact over the last 15yrs... My Suunto cobra finally crapped out me a couple of weeks ago. Haven't been able to get it fixed yet... Man that new Atomic PDC is Sweeeet!! I want one, just have to wait a couple of weeks before I can afford to fork over another mortgage payment on one... I'm on week 3 and no PDC yet. 30 dives all by the book(EAD, NAUI Tables), really haven't noticed a decrease in bottom time. Oh wait, thats because the boat captains usually set the dive time down here(florida)...HMMM 50 min dive max, 1-1 1/2 SI...another 50min max... Im good for 45mins on bottom 50'-60' for 2 dives (both Nitrox) everyday with or without a computer... I guess if I didn't know the tables or how to use EAD this might be a problem, but its not. A PDC is only really useful to me when exceeding say 100' otherwise its just another toy... I think it makes more sense to teach the tables then it does to buy a computer here in south florida...

 

[Atom]

Perhaps it's the level at which dive tables are taught that is at issue. I'm not advocating that the basic scuba class these days, should teach a student to be highly proficient at using the dive tables, rather to teach them what they are, how they work and why they might want to use a dive table. If a student wants an intimate knowledge of using dive tables, then one can read some mighty fine examples online, or ask the instructor to give, or sell them some instruction on the subject.

What proficiency levels are there with tables? To me, you either know how to use them correctly or not. And I'd say it's not very useful to go over them so quickly that students can't use them by themselves afterwards, some people have to work with them a lot during the course to get the hang of them.

You have to leave the class knowing how to properly plan a dive using something, whatever it is. I think it's more important to be able to use one tool properly than to know a bit about all of em but not able to reliably plan a dive with any of them.

 

[The Chairman]

Are you aware of any empirical study that shows computers are inherently more risky than tables?

Early on, I was shocked by one of DAN's reports about DCS. It's my recollection that ALL of the people were diving with PDCs.

Also, I was shocked to see so many divers riding the NDL. The attitude was that they could increase their BT dramatically by ascending a couple of feet at a time. Rather than planning a dive and sticking to their plan, they were simply flying by the seat of their PDCs. It's my opinion that the algorithms weren't designed to be used in such a way.

I don't disagree, btw, that diver training needs to be different than for tables, and that divers need to not be 'flying the computer.' Rather, it is my understanding that many computers, if not most, being more conservative than tables makes the comparison non-trivial. It comes down to opinion rather than data. If I'm wrong and there is data out there to support your position, I'd be more than happy to admit that I'm wrong about yet something else

I remember re-reading a NAUI diver's manual as a newly minted instructor. It actually suggested that you should increase your safety stop to five minutes if you were diving a computer. I can't remember why it caught my eye, but I know I wasn't teaching that very effectively. Talking to fellow instructors, it became apparent that most (all?) had missed this caveat as well.

Now fast forward to a DAN talk at the History of Diving Museum a few years ago. The presenter suggested that they could tell the type of diver by the type of DCS. If it was Type I they were a commercial diver, and Type II meant that you were a recreational diver. Statistically, getting bent is still a statistical anomaly: a blip. Still, that they could be so sure HOW you would be bent really affected me that night. Later, he was discussing tissue half times and pointed out that neural fluids were almost as quick as blood.

It's not much of a stretch to see that the total increased bottom time allows for a complete saturation of the neural fluids. That in itself makes PDCs more dangerous in my eyes as well as making a five minute safety stop my SOP.