PADI tables finally going away?

[Kevrumbo]

Still waiting on straight forward responses to my questions to try and figure out what your issues actually are. How about just some 'yes' or 'no' answers. Then maybe expound on that with a few points about what your issues are.

Again, can you try to drop the rhetoric. Just for one post could you use "tables" and "PDCs" or "computers" without cluttering up the discussion with whatever it is you mean by 'analog' since we clearly are too stupid to understand, and tell us what your issues with not teaching from tables are?

You can do it if you try.

If you, for example, say:

"Tables are necessary to understand the basics of decompression theory." Then you've made a specific, concise claim that we can discuss.

But without actually knowing what your issue is other than whatever tables being analog has to do with it (again, we're just too dumb) then we're going no where.

Thanks.

But even without that, let's try and pick apart your claims as I understand them:

This is a poor analogy that is not applicable here. Neither the PDC nor the Table are building the model by hand. They are both representative of deeper items that require a lot of pre-calculations and research to provide -- the details of which are not relevant to understanding the output.

The Dive table is far more comparable to a logarithmic table than learning basic arithmetic. What is comparable to basic mathematical operations would be the underlying decompression theory and understanding of nitrogen loading and off-gassing as related to depth and time.

Do you believe that decompression theory can not be taught without tables? (A simple answer please, it really is a yes or no question).

There are two issues here, but both are wrapped up into somehow making "fundamental knowledge" directly tied to tables. Tables are not necessary to teach fundamental knowledge about decompression. Indeed, tables themselves come from the same sort of calculations that the PDC is dynamically doing.

Do you believe that decompression theory can not be taught without tables? (A simple answer please, it really is a yes or no question).

I'd agree with that point. But all analogies have their limits. Because this is a relatively sound analogy does not make the analogy of how basic mathematical functions are to calculators correctly comparable with how dive tables are to dive computers.

Do you believe that decompression theory can not be taught without tables? (A simple answer please, it really is a yes or no question).

This is a false analogy. A correct analogy would be that foundation and greater utility is first learning and comprehending basic decompression theory and dive planning, while the simplified approximation of the results of the model (either a table or a PDC) is a tool to make dive planning feasible for someone unable to work out the calculations of the underlying model (which is most of us).

Do you believe that decompression theory can not be taught without tables? (A simple answer please, it really is a yes or no question).

With the exception of losing it, or damaging it so that it is unreadable, sure. But you still have to rely on a bottom timer and depth gage, both of which have failure rates. The timer will also have a battery that could die at a most inconvenient time if you are not being a responsible diver and checking your gear and caring for it appropriately.

I agree on both claims about the properties of dive computers.

Just like your bottom timer. Or if your depth gage fails. How are those intrinsically different?


Yes, the method of calculating the model can be different (though most all tables have been produced using computers for many years now, so the claim really isn't entirely true). But so what? Do you have any evidence at all that the underlying model being calculated is different in any way that effects divers?

I can calculate the the value of Pi using exceedingly precise measurements of a circle's properties, and do a whole lot of long division by hand.

I can use various logarithmic tables and solve Euler's identity for Pi.

I can calculate the value of pi by throwing food

I can calculate the value of pi using some elementary calculus and the formula

or

I can use particle physics and Heisenberg's uncertinty principle

I can use any number of discrete functions to calculate PI to any arbitrary number of digits, such as:

or

Would you like to explain how one of these methods is inherently superior to another?

I can look up a pre-printed value of pi, to say, 10,000 digits

Do you believe that one of those methods to be superior to another? Are the continuous functions going to provide you a better value for pi than the discrete functions?

The brevity, wisdom and honesty of my inductive opinions speaks for itself . . .you may claim naivety on my part by your analysis which is fine. That's your own subjective deduction & analysis, and I choose not to comment on your interpretation any further.

(Good Diving & Karma to all this Weekend. . .:cool2

 

[The Chairman]

The brevity, wisdom and honesty of my inductive opinions speaks for itself .

I would have to agree Kev, I just don't think you're listening.

 

[Kingpatzer]

The brevity, wisdom and honesty of my inductive opinions speaks for itself . . .you may claim naivety on my part by your analysis which is fine. That's your own subjective deduction & analysis, and I choose not to comment on your interpretation any further.

(Good Diving & Karma to all this Weekend. . .:cool2

I am honestly trying to have a discussion with you. The starting point of which is actually trying to understand whatever the heck it is you're claiming. To that end, pleases be so kind as to answer a single question with a direct answer, namely:

Do you believe that decompression theory can not be adequately taught without tables?

 

[DiveNav]

......But instead of spending the time in basic OW learning to look up the table, what if that same class time were spent learning to interpret computers better instead? .........

I agree

......then they would know to respect that bar graph and .....

Unfortunately not all dive computers have one :depressed:
Divers need to learn THEIR dive computer

 

[Lorenzoid]

Unfortunately not all classes have access to dive computers. Sure, even dive ops in remote corners of the world are increasingly acquiring computers, but the day when every PADI dive center is able to ensure that all students have the opportunity to try a computer is not here yet. Until that day is here, or until PADI devises some better teaching tool--PADI will not be able to "do away" with the tables.

 

[John_B]

Why is a 30 minute SIT a bad idea? Because it eats into the NDL of your subsequent dive. And that's easily read off a computer, no?

IF you understand what you are looking at, and also understand how the variables interact with each other. Do most new divers have any grasp of that? Most that I see don't.

I will concede that maybe RNT is easier to teach with a table that lists it (as opposed to a bar graph on a computer display). However I maintain that the best possible result of teaching deco theory is an intuitive understanding of how profile affects gas loading - in water deco as opposed to out of water deco - and unequivocally dive computers which react to profile are the best way to show that.

If an aware computer diver looks down and sees that he's at (or about at) "the limit," he knows that all he needs to is ascend a bit and continue diving. If a properly taught table diver looks down and sees that he's at "the limit," he believes (because that's what he has been taught) that he must immediately begin a direct ascent to the surface. The former, blessed by a display that reacts in real time to the dive profile, gains an innate (albeit not fundamental) understanding of practical decompression theory. The latter has his no-more-fundamental understanding of decompression hamstrung by the fairly uncommon (wreck divers aside) constraints of square profiles.

I think we're agreeing that it's possible to "fly" a PDC to the NDL. We're just reaching different conclusions whether that's a good thing or whether it's just encouraging people to completely turn off their own brains when it comes to dive planning.

There guys right now over in the "Are Suunto computers really that conservative?" thread who honestly believe that simply flying down to the NDL with a more conservative PDC will keep them out of the chamber.

Clearly there are a lot of new divers who aren't learning to "plan your dive, dive your plan" (regardless of what might be being taught).

Which, circling back to where I came into this discussion, is my complaint with how most instructors teach PDCs these days. And that seems to be true whether new OW students are being taught to dive with a PDC, or whether they are taught with tables that they throw out and replace with a PDC on their fifth open water dive.

 

[The Chairman]

IF you understand what you are looking at, and also understand how the variables interact with each other. Do most new divers have any grasp of that? Most that I see don't.

Only because you taught them tables.

I think we're agreeing that it's possible to "fly" a PDC to the NDL.

You can fly a table to NDL. What's the dif?

There guys right now over in the "Are Suunto computers really that conservative?" thread who think flying down to the NDL with a more conservative PDC will keep them out of the chamber.

Only because someone failed to teach them PDCs.

Clearly there are a lot of new divers who aren't learning to "plan your dive, dive your plan" (regardless of what might be being taught).

See my previous comment.

 

[Kingpatzer]

Clearly there are a lot of new divers who aren't learning to "plan your dive, dive your plan" (regardless of what might be being taught).

I don't disagree with that. But that also has nothing to do with PDCs versus tables. Dive boat guides push "trust me" diving on the luddites and cutting edge alike.

Which, circling back to where I came into this discussion, is my complaint with how most instructors teach PDCs these days. And that seems to be true whether new OW students are being taught to dive with a PDC, or whether they are taught with tables that they throw out and replace with a PDC on their fifth open water dive.

I think that is the basis for a good discussion. One of my personal beefs with the new PADI exams around PDCs over tables is that the old table tests included questions that required planning dives. It was possible to look at those questions as a real litmus test to see if they understood dive planning. The new computer questions do not include having to plan a dive, but rather have general knowledge about using computers.

The questions themselves could be seen to suggest that flying the computer rather than planning the dive is acceptable.

 

[Quero]

I think we're agreeing that it's possible to "fly" a PDC to the NDL.

You can fly a table to NDL. What's the dif?

I think that is the basis for a good discussion. One of my personal beefs with the new PADI exams around PDCs over tables is that the old table tests included questions that required planning dives. It was possible to look at those questions as a real litmus test to see if they understood dive planning. The new computer questions do not include having to plan a dive, but rather have general knowledge about using computers.

The questions themselves could be seen to suggest that flying the computer rather than planning the dive is acceptable.

It has become a thought-provoking discussion (now that it seems to have passed the "thermocline" of debating word choice and other trivial matters). Here's what I've picked out from it to gain personal insight:

From what I can gather, the main point of contention as expressed in the quotes above is the question of whether by teaching tables we make students determine their own NDLs in advance of the dive and then have them execute the dive accordingly, whereas by teaching computers we allow the computer to make the determination of the NDL during the course of the dive and then the diver simply follows the computer's recommendations.

It appears to me that the way both table instruction has taken place as well as the way computer instruction now takes place in PADI materials encourage the idea that diving to the limits of either will probably keep you safe. I know, I know, we do say "don't dive to the limits; every person is different" in the midst of that "probably" in "probably keep you safe." However, the table questions in the examples and the tests that have to do with NDL and miminum SI all focus table-users' attention on the limiting pressure group, not on some pressure group that will leave a cushion. Similarly, discussion of which brand of dive computer is more "conservative" on NDLs exposes an attitude that it's the NDL limit that keeps the diver safe, not the diver's own determination of how close s/he is planning to come to the NDL.

So yeah, I will agree with both John and Pete that the way the teaching materials have been and currently are set up subliminally promotes "flying" the tool, whether it be a computer or a table, if we allow a focus only on the NDL in our training sessions. I fail to see the difference in safe diving practice between pre-planning and then executing a dive to the limits of the NDL and flying a computer to the limits of the NDL during the course of a dive. Both would be equally risky from a "keep me out of the chamber" perspective.

This leaves me at the point where I think about how to rectify this failing, both for computer students and for table students. In regard to teaching computer use, I already give a lot of practical emphasis to watching the NDL on the computer and telling my divers (both students and fun divers) not to let the computer count down to less than 7 minutes NDL on the deep portions of our dives (>18 meters). What this does, on "deep" dives between 18 meters/60 feet and 30 meters/100 ft, is keep divers out of that gray area that we can see on the PADI tables.

I suppose John will argue that this is still "flying" the computer rather than planning the dive given that we do it "on the fly," but we can easily check the NDL for an imminent dive on the computer as if it were a square profile and still "fly" the computer during the dive as a fail-safe measure. Besides, planning really only works well on square profiles, which we rarely dive where I am (we do repetitive multi-level dives on multiple days at least 85% of the time). To me, checking these numbers and reminding students that no matter what cool thing we see at our maximum depth (i.e., a photogenic leopard shark sleeping in the sand at 25 meters), we will spend no more than XX minutes at that maximum depth, all the while watching our NDL readouts. That is no less a "plan" than if I were to decide to stay four pressure groups above the NDL when working out a square profile deep dive on a table and then staying within that time limit by watching a depth timer.

In regard to teaching tables, what I have never tried is to present students with table problems for determining minimum SI times that allow them to plan a dive to a particular depth but rather than planning to the NDL of that depth, planning to four pressure groups above it as a cushion. I'm going to play around with this idea a little, and I'm also going to play around with the idea of watching the dive planning function on the computer to see whether we can plan dives for 7 minutes less than the maximum time at a given depth, or if it has to stay simply as my "rule" for deep diving "on the fly."

Anyway, I've drawn no unshakable conclusions yet, so please, continue the debate. It has surely given me food for thought, which is one great function of this I-2-I forum.

 

[The Chairman]

I already give a lot of practical emphasis to watching the NDL on the computer and telling my divers (both students and fun divers) not to let the computer count down to less than 7 minutes NDL on the deep portions of our dives (>18 meters).

I don't know that I have quantified this with my students, but I like it! What made you settle on 7 minutes?