Nitrox tables going too?

[rubixcube]

So why do they need to learn the longer and less practical method if they are going to use the computer?

Multiple reasons have been listed above, there are cases when tables may be useful. Among others being able to salvage dives if your computer craps out and you don't have a backup computer, personally I would prefer to dive with a timer/depth gauge and tables than wait 24 hours.

 

[TMHeimer]

Exactly my thoughts and why I started the thread.

 

[xyrandomyx]

Multiple reasons have been listed above, there are cases when tables may be useful. Among others being able to salvage dives if your computer craps out and you don't have a backup computer, personally I would prefer to dive with a timer/depth gauge and tables than wait 24 hours.

That's certainly true. It's also true that carrying and knowing how to use a slide rule will be useful if your calculator fails and you don't have a backup calculator. I'd say most people would think it's reasonable not to bother.

If I was that worried about missing out on diving because my computer failed, I'd think the simplest solution would be to get a backup computer. I don't see how I'm more likely to forget to bring my backup computer than forget to bring my tables.

All that said, I'm currently using tables (well, the PADI eRDPML). My LDS doesn't rent computers and I haven't decided on a model to buy (too many shiny options with many features to choose from). My dives are currently limited by air and cold, I've yet to do a local dive that comes close to NDLs, so I'm not in a rush. I am considering buying something relatively cheap and simple, though, and, if the option was available to me, I'd certainly rent instead of using tables.

 

[explorer08]

You guys are killing me! I can almost hear Doris Day singing "Gonna Take a Sentimental Journey"! Tables have their place, but PDCs have all but replaced them for recreational diving.

Here are some facts:

• Understanding Deco theory is not dependent on learning tables.
• PDCs (Personal Dive Computers) are not derived from tables. Both are derived from algorithms.
• Instructors should be teaching students to use the equipment they will be diving with. For most divers this is a PDC and not tables.
• PDCs don't get narced.
• PDCs provide an accurate record of your dives and safety stops.
• PDCs represent N2 buildup with an easy to understand (intuitive) bar graph rather than confusing "letter groups".
• PDCs don't forget when you submerged or when you surfaced.
• PDCs don't forget to reset the witness mark on your depth gauge.
• PDCs sound an alarm when you exceed your NDL, MOD or ascent rate.
• Learning PDCs can be less intimidating to a novice diver.

I don't teach tables to my OW students unless they specifically ask me to. No one has asked so far.

I agree to 100% with you!!!

And when I read in several postings in this thread that divers need a table as backup for the case their computer fails, I just can laugh - or should I better cry?
I can't hear this diving myth anymore.
Who ever actually conducts a square profile dive? I guess nobody except some wreck divers or similar. I would claim that more than 90% of recreational divers do multilevel dives. And according to Murphy's law PDC's, if they ever fail at all, they don't do it in the very beginning of the dive. But if they fail later on, usually you are a long way out of the frame of any table. And what's about multiday diving? Does anybody honestly want to claim that he, after a series of serveral days with serveral dives each day, is able to recalculate his saturation level with a table? Even with a PDC it is more like reading coffee grounds than.
The only backup for a PDC is a second PDC!

 

[Kingpatzer]

It's not parallel in that way no, but I make the parallel that the tables are the longer and less practical method that will not typically be used in day to day diving (in other words the math processes) and the computers are the faster and easier method that are what most will almost always use when possible (the calculator).

Sorry, but it is just not a valid analogy. Both tables and calculators are tools for automating, simplifying and abstracting dive theory calculations, while calculators and long division are not both tools. Rather, one is a tool and the other is an algorithm. Further, the calculator neither abstracts nor simplifies a mathematical operation (floating point issues set aside as a special case where some abstraction does occur). Instead it performs the mathematical operation indicated.

 

[explorer08]

The problem with this logic is that it is easily taken too far. After all does a student really need to know all that physics? Couldn't a diver simply follow sets of safety rules and guidelines and still dive safely? Well yes they could, but I don't see to many arguments saying that dive physics and physiology need to be cut from courses. If taken to extreme levels classes could devolve into even simpler and shorter than they are now.
Instructor: "Strap this to you, breathe from this, listen to what this doohickey says, equalize, don't hold your breath, and don't drown. Got it? Good here's your card, have fun."

There is a mistake in your thoughts. You are comparing apples to pears.
Physics haven't changed since the occurance of scuba diving, same is with physiology, but technology has changed a lot. So we may discuss today, how intense student divers have to know physics and physiology on what level, but the content never changes. But as well as we don't use horsecollar BCD's anymore, as well as we don't use BCD's without a lowpressure inflator today and as well as we don't dive without alternate air sources today, we also should not use tables anymore. They are simply antiquated today!
And they should not simply been taken out of the classes, they should be substituted by the equipment which is in use today - PCD's.

 

[Charlie99]

The only backup for a PDC is a second PDC!

Not true. Tables can be used as a backup, even after multilevel dives. For example, using the PADI tables, if you can safely assume that you have stayed within NDL, you simply assume that you surfaced in pressure group Z and go from there. The penalty for overestimating your N2 loading by assuming pressure group Z is that your surface interval will be a bit longer than it would have been had you perfect knowledge of your multilevel profile and worked it out on a wheel. So you might have to wait for 90 minutes until your next dive rather than splashing in after 60 minutes.

You have that 60 minutes or 90 minutes until the next dive to read the instructions and figure out the table. Or you find somebody on the boat that can figure it out.

Or you look at your buddy's computer and fudge. (ooops, did I really mention what people do in the real world...)

 

[--tom--]

Let me continue the example I used in my first post.Thanks to elementary school I know how to do long division, do I ever need to actually go through that process in real life? No not usually, after all I can just use a calculator it's faster and easier. But has that knowledge been useful in a few circumstances when I needed to do simple math and was without a calculator, and am I grateful I know that process? Yes, I am. IMHO I don't think it's necessary to cut a relatively short and simple and possibly useful part of what is typically already a very short and extremely easy course.

While I agree with the sentiment, I have to disagree with the argument. Tables are simply a spreadsheet portraying what is supposed to be happening with nitrogen loading on a square profile (single depth). We are not working an algorithm, we are reading a chart.

Isn't that exactly what a computer is doing, except that it is faster than I am and can do a sample rate every twenty seconds? Hence doing a better job of calculating a multi-level dive? So I read a screen instead of reading a chart, still reading.

That an instructor (or student) prefers to include tables in a nitrox class is a personal preference that I won't condemn it. I will even encourage it, if you want, but please realize that Tables are in all likelihood, going the way of the slide rule.

HOWEVER, I will condemn any instructor that teaches tables and OMITS computer instruction. That IMHO would be bordering negligence.

 

[TMHeimer]

On the other hand, cheap dive watches cost a lot less than computers. My $29 one has lasted 3-4 years now. Also, a large % of my dives are in fact single depth, as it is common in our area. Even on a wreck dive I am pretty much on the bottom the whole time.

 

[rubixcube]

Okay I'll admit my metaphors have been pretty poor (I swear they sounded better in my head), perhaps I'll simply state my opinion on the matter without them. I don't see a really good reason to not include them in the class.They are not difficult or time consuming to learn, having them in a class does not extend the class by large amounts of time. This is even more true for the nitrox course when the student already knows how to use tables. The tables have potential uses some of which have been mentioned already in this thread. I don't think that excluding a concept that is potentially useful just because it's not likely to be used is fair to those learning.