One Question.. when teaching computers do you teach a generic model, provide a student with one each and teach that (by teach I mean understand the display) or cover different examples? - Only assign out of interest with no hidden agenda
It depends on the student's interest.
I'm a PADI instructor so when I teach tables I teach the PADI tables "by the book" in the sense that they have to understand the use of tables to PADI's satisfaction. I'm limited in that way because I'm required to use PADI's tests to determine if they understand it and I'm not allowed to create my own.
That said, I'm *never* satisfied with any answer on the theory if the student doesn't understand the *why* behind it. It's often a running joke with my students. They'll answer a question and say, "and now you want to know why..." LOL
In relation to the tables, for example, the *why* of things like the maximum ascent rate, the reasons for special rules for longer surface intervals with groups WXYZ and *why* you are "clear" on tables after 12 hours when you are not clear on a computer for (usually) 3 days are all things that I explain in detail in terms of the model. Differences in the model are the reason that you can't accurately fall back from computers to tables. It's like having two maps of the same area but at different scales. You can make them line up at certain points, but at others they will not.
These kinds of topics are things that I cover as a standard part of the computers/tables discussion.
I have had students in the past who wanted to know more. Several were engineers who were interested out of professional curiosity.
I'm going to admit here that I can't follow the mathematics of RGBM well enough to explain it to someone else even having taken advanced mathematics through to the 3rd year of university. I understand it in terms of "squares on whiteboards" and that's about it. However, I know pretty much everything there is to know about the Haldane model, so if a student wants more information about the actual implementation of the model then I'm more than willing to explain it, and that's the model I use. This usually requires scheduling a separate session because it takes more than a few minutes to explain it in detail but I'm always willing to go as deep as the student wants.
In terms of other aspects of deco theory (ascents strategies, compensating for physiological risk factors, how to bring theory and practice together) I usually address this as part of series of sessions I have with them about dive planning. What I try to do is to get students to a point where they understand the theory but that they are able to apply it and build habits (addressing the *why*) to keep their diving controlled and safe in terms of understanding and managing the risk of decompression accidents.
I don't know if that answers your question but I hope it did.
R..
---------- Post added March 17th, 2014 at 11:14 AM ----------
Ok.... well I wasn't able to be online yesterday (I was out diving of all things...) so I've missed too much to respond in detail to everything that's happened since my last post. Therefore I will respond generally.
This thread has all the elements of all the discussions about the tables/computers controversy that we usually see.
on the "tables are essential" side the arguments are :
1) they are good for backup
2) they are cheaper than computers
3) they allow for teaching deco theory
4) they make the diver more skilled/knowledgeable
T.C. has added his own extra "flavour" to this thread by also suggesting that if a student does not understand tables and/or is not able to remember it permanently after the class that there must be someone to blame. This is a twist that we don't see all the time. He suggested that I must be an inferior instructor because I don't agree with him or that my observations that people can forget things means that those people are not taking "personal responsibility". This edgy manner of debate makes for good "gladiator sport" but is so utterly devoid of objectivity that I refused to respond to it. Perhaps someone else would like to get into the ring about this.....
IN the course of this thread, we've argued that using tables for a backup for a computer can only be done in a very narrow bandwidth of dives. There are many "valid" computer dives that would make you (in theory) "dead" on the tables. Moreover, differences in decompression models means that they don't correspond well to one another. It's kind of like imperial and metric bolts. They look (about) the same, until you try to put a wrench on them.
We've also made it clear that falling back from computers to tables may not--depending on the context--give you more bottom time than falling back from one computer to another computer, either one you rent or one you own. In some situations falling back from computers to tables could "save a dive" but I think we've established that this is not a universal truth.
T.C. makes a valid point that tables are cheaper than computers. Tables cost about $65 IIRC and you can download them online for free. A simple computer costs about $250. Although computers have become very affordable and you can rent them in most places, there are still some divers who are on very tight budgets and I believe for a small group of people that the difference in price could make the difference between diving and not diving. I was one of them. I learned to dive when I was at university in 1984. I went to university on a shoestring budget and while I *really* wanted to dive, it meant that I sometimes literally had to choose between eating and diving (guess what I chose?). The question is, however, should *everyone* be forced to learn tables because a select few are barely able to afford it?
In terms of teaching deco theory. It's clear to me that there has been an enormous improvement in the quality of education with respect to deco theory over the last... say, 10-15 years. Yes, some instructors still have to learn how to teach deco theory without using tables as an example, but teaching tables is no guarantee that the student understands deco theory. This is the core of the transition we're in right now, if you ask me.
It was argued that the diver is *less* skilled -- i.e. less capable -- as a diver if they do not understand tables. This point could do with more debate. In my mind the *skill* of a diver has to do with whether or not the are able to plan and execute a given dive. The tools they use to do that are of secondary importance in my mind. T.C. has repeatedly argued that the tools the diver uses *do* define whether or not they are skilled as divers. I tried arguing that a modern mathematician may be skilled without knowing how an abacus works and a modern diver may be skilled without knowing how a J-valve works. Likewise, I think I modern sailor may be "skilled" without being able to navigate with a sextant. I have the impression that this point was lost in the melee because examples of tanks, space shuttles and so forth.
R..
Why drop a small piece of standard equipment? 
