PADI Nitrox, Computer vs. table class

[MarineResearch]

A quality educator will be able to convey all the important information with either tool.





..whereas sliding ones finger along rows and columns on a table provides a deep intrinsic understanding of the underlying principles and mathematics?

Hardly, but at least learning to use tables reinforces the issue of residual nitrogen and multiple dive planning. As for actual diving, tables are pretty much useless compared to computers. Ironically, tables are still included in the advanced nitrox and decompression procedures course material.

 

[Blackwood]

The thing about learning about tables is one can see the decompression limits and how they are affected by depth. I think tables give the diver much more insight into the dynamics of nitrogen loading.

Quite the opposite. They give you a cursory look at static nitrogen loading. A computer, on the other hand, can show you in real time how profile (i.e. depth vs time) affects nitrogen loading.

When one uses a computer, one is just doing what it tells you to do.

A. says who, and
B. how is that different than using a table?

Hardly, but at least learning to use tables reinforces the issue of residual nitrogen and multiple dive planning.

Maybe, but can't you use a computer to reinforce those same issues? I imagine a much more substantial understanding of realistic dives (most aren't square) can be conveyed by using a tool which reacts rather than one that simply lists numbers.

Ironically, tables are still included in the advanced nitrox and decompression procedures course material.

True. Possibly due to the cost of multi-gas computers compared to printed tables or desktop software? Or maybe because people often like to tweak profiles, and having a hard-coded algorithm telling you to do something you don't want to do would be annoying. *shrug*


While on the subject of irony, I don't use decompression computers myself (I have a computer, but it's in gauge mode). I just see them as potentially being far more valuable to the instruction of practical decompression than tables.

 

[Charlie99]

..whereas sliding ones finger along rows and columns on a table provides a deep intrinsic understanding of the underlying principles and mathematics?

Elegantly put.

I find that understanding underlying principles, in the long run, is more important than calculations that can easily be looked up (tables) or supplied by electronics (dive computer).

It may very well have changed in the 13 years since I took it, but back then the PADI Enriched Air course was heavy on calculations and very light on basic concepts.

For example, a formula for EAD depth was given, and examples worked out, but never did the material say simply, clearly, and explicitly that the concept of EAD was that of finding the depth on air which has the same ppN2 as a given depth on nitrox.

My instructor did not understand that basic concept, and was surprised by how easily I was able to derive the EAD formula, starting with the basics of depth to absolute pressure conversion, and then multiplying by the fraction N2.

ppO2 tracking was covered much more thoroughly, although it was a mystery to me why O2 exposure from 23-1/2 hours ago applied with full effect and then had zero effect 1/2 hour later. Of course, a computer oriented course would discuss that most computers use exponential decay for tracing CNS oxtox exposure, with a halftime of only 60 minutes or 90 minutes, depending upon the computer, and if they track pulmonary O2 loading at all, do so with a much slower decay time.

 

[UCFKnightDiver]

Why can't classes teach both? If you learn to use tables and a computer just more tools in your tool box. Sillyness to seperate the two. Oh and I don't see computers being very difficult to use/learn not sure why there's a seperate class for them an either or type of deal, I also hope that things such as mod calculation/ead calcs etc arn't skipped over which may be the case in a computer only class because of planning mode as I feel they are important.

 

[bracko]

having an appreciation of where the data comes from is my preference.

in school did anyone else wonder how or why sine, cosine and tan worked on their calculator when doing trig? I did, and it annoyed me when (in year 8, 13-14yo) my teacher told me not to worry, it was too hard to explain... (truth be told, he probably didn't know)

it wasn't until 2nd year applied maths in my engineering degree i was taught where they came from and why they worked....

receiving the numbers a calculator (or computer) spits out is only half the solution, having an understanding that that number is more or less right is far more important.

therefore my preference would be to learn about the risks of nitrox, where the equations come from and how the tables were made. then how the tables were applied to computers. if divers wish to glase over and rote learn the 2 or so questions on the theory, then that's their own decision, if divers want to understand and read into the background, then all the better.

 

[robbcayman]

PADI Instructor news sent this out today...

"Although you can still acquire EANx RDP Tables and teach their use during your Enriched Air Diver courses, at some point in the future, PADI Offices will discontinue carrying these products. If you haven't made the switch from tables to computers yet, please consider making the transition to the computer-based program."

At this point, I still teach the tables. I guess that is going to change.

I knew this was coming, but I didn't think it would happen this fast. You can just get so much more benefit out of using a computer for bottom time. The tables can't account for changes in dive plans. Like I said earlier, the computer is constantly recalculating. I think it's a smart move by PADI.

 

[BigJimDiver]

First let me say I have gained a lot from all the very well thought out and varied responses to the few questions I have posted on Scubaboard up to now. It's truly an education in and of itself, and I appreciate everyone taking the time to give their perspective.

There's no question my son will dive with a nitrox capable computer, particularly on any liveaboard trip we do. If we didn’t it probably it wouldn't seem to make sense to spend on a liveaboard because our bottom time would be so much more limited diving off tables.

My real question is more about the content of the Computer class. I took the "traditional" (table based) class, and assumed as many of you pointed out the computer based class will teach him all of the same safety and physiological aspects of Nitrox. I am having trouble figuring out what there is to learn in a Class about specifically diving with a computer that one wouldn't learn by reading their dive computer manual thoroughly which should be done anyway. I also thought it would be a good idea for him to go through the process of learning how to do tables, and maybe getting a slightly better grasp of EAD by working the tables a bit, than one might get "just" doing the computer class. I personally don't see any downside to it and was reaching out with my question, particularly to the Instructors, to ask if I am missing something, if there's topics they teach in the Computer version of the class that would be useful and he'd miss if he took the tables version.

Thanks again to all!

 

[Kern]

having an appreciation of where the data comes from is my preference.

in school did anyone else wonder how or why sine, cosine and tan worked on their calculator when doing trig? I did, and it annoyed me when (in year 8, 13-14yo) my teacher told me not to worry, it was too hard to explain... (truth be told, he probably didn't know)

it wasn't until 2nd year applied maths in my engineering degree i was taught where they came from and why they worked....

receiving the numbers a calculator (or computer) spits out is only half the solution, having an understanding that that number is more or less right is far more important.

therefore my preference would be to learn about the risks of nitrox, where the equations come from and how the tables were made. then how the tables were applied to computers. if divers wish to glase over and rote learn the 2 or so questions on the theory, then that's their own decision, if divers want to understand and read into the background, then all the better.

Tables aren't applied to computers, output from tables & computers are both generated from mathematical models/algorithms. If the table & the computer uses the same algorithm, they generate the same outcomes for the same inputs. Learning on tables won't teach you any more about the underlying maths of the model than learning on a computer.

 

[Kingpatzer]

having an appreciation of where the data comes from is my preference.

The tables don't tell you where the data comes from. They are the pre-calculated results of very complex mathematical models. And I assure you that knowing those outputs tells you nothing about the underlying model.

You might well be able to tell me what pressure group you're in after 8 minutes at 90 feet. But so what? How many, and which, tissue compartments of your model are fully saturated? What is the level of saturation of the remaining tissue compartments? To which body tissues are those theoretical compartments most analogous? Based on the model are you better off ascending at 60' a minute or 30' a minute from that depth? What ascent rate from that depth will be too slow and allow your tissues will continue to on-gas? How does being in that pressure group after your 8/90 dive differ from entering into that pressure group from a dive with a maximum depth of 60'?

Can you answer any of those questions from a table?

You can answer a few of them from some computers after a dive, but honestly, you can't do much better with a computer either. Neither tool reveals the underlying model. Any contention to the contrary simply demonstrates ignorance as to what a decompression model looks like.

 

[dburg30]

While theory and all that jazz should be taught no matter what, I still stick by my reasoning of learning the tables. If you are familiar with them, and your computer goes belly up on a trip, you can still dive. If you've not learned the tables and your computer dies.. what then?