PADI class has dive calculator instead of tables now?

[Blackwood]

I believe her point was that the lack of air in an AL80 would decrease their dive time below the NDL. Which may be true, depending on the diver, at least for the first dive of the day.

To be fair, I don't think she was suggesting that just jumping in with an 80 and using it until it's gone is a good plan. She was talking about two divers using one computer, and simply mentioned that gas is generally more constraining than NDL in a post prefaced with "Although I don't think sharing a computer is a practice to be encouraged..."

As you noted, as dives are repeated, "NDL" decreases for a given depth. However, that decrease applies to both divers. So yah, on the 4th or 5th dive, that gas supply may outlast NDL, but it's irrelevant to the concerns of sharing a computer which I personally believe are mitigated by general algorithmic conservatism and, more importantly, buddy proximity. If you are so far away from someone that you have a drastically different inert gas loading, he/she is not your buddy; you're solo. I'm not very concerned with a few feet here or there (in spite of table methodology which would have us conclude that while one guy is A-OK at 79 feet, his buddy is screwed at 81).



That said, I don't encourage it either... it's not my position to encourage or discourage anything.

 

[boulderjohn]

Everyone needs to learn the tables. If nothing else, you need to be able to follow altitude and nitrox tables, should you encounter them in the course of your diving career. The tools may be nice, but should not entirely supplant the instruction of tables.

Altitude and nitrox adjustments are made on the eRDPml the same way they are done on a table.

Here are the big things I have noticed now that I have taught a bunch of classes with eRDPmls rather than tables.

1. Instruction on how to use it takes less than half the time it took to teach the tables. Far less.

2. The most common mistake of all that students made with the tables--reading the wrong column--is eliminated.

3. Students can plan multi-level dives easily.

4. Since I always taught the decompression theory that both tables and the eRDPml measure separately, that was not effected.

 

[wrecker007]

I have been thinking of this whole technology thing for a while and it seems to me I went through this whole thing a lot of years ago when calculators first began to hit the market. At the time, my math teachers all insisted that we still learn how to use slide rules. It's kind of cool still having an understanding of slide rulers but once I figured out that a simple calculator could do the job in a much more direct way, I stopped using the slide rule. The same thing happened once computers came along in particular with the advent of programs like Excel that do all of the calculations (including very complex ones) with no real input from the user. I can not imagine not using a dive computer in this day & age. I know there are some who don't see the need because after all you can plan & calculate a lot with tables, watch & depth gage. But the computer calculates continually taking into consideration actual depths along the way. And since redundancy should be the mantra of every diver, I carry a backup just in case. It's no different for me than the idea of carrying a backup light on a night dive. I say, glad to be rid of the tables & hail to the modern geeks of technology who are striving to bring the sport into this century.

 

[TSandM]

For all we know, this new diver who is sharing his buddy's computer is sitting down and planning out each dive WITH the buddy (I know, I know, it's unlikely, but . . . ) The sole purpose of my post was to refute the accusation that the diver could get into decompression trouble by being a few feet shallower or deeper than his buddy. The math says he can't.