Computer vs tables

[mark01]

I use a computer and based on the type of diving I am doing (recreational) and my training thus far, this seems to make sense. In some of the reading I have done thus far, I have run across the DIR perspective and I find some practicality and utility in it.

Having said that, I don't see myself going to overhead enviroments, wreck
penetration, or dives which take me deeper than recreational depths, but I do like aspects of DIR equipment configuration.

In the reading I've done regarding the DIR orientation, the use of computers is shunned for a variety of reasons and I think I understand why - at least from their perspective.

Do DIR folks only dive square profiles? Is there a method to using tables which would allow the apparent flexibility offered by using a computer??

TIA

Mark

 

[Pumpkin King]

Why not calculate multiple dives from the tables with 0:00 surface interval? Tables don't give you credit for ascents anyway; bottom time is only down and at depth. Can anybody confirm this as correct?

 

[Jasonmh]

You might want to consider posting this question in the DIR forum, might get more of the people who can answer your question to see it.

 

[TSandM]

Many of us, as we make the transition to DIR diving, continue to use our computers for a while, as we gain facility with following the dive accurately.

Most of us eventually use the tables GUE teaches, and do some kind of depth averaging for non-square-profile dives. There are gauges now that do a resettable depth averaging, but as Andrew Georgitsis told us a few weeks ago, they defeat the purpose. The purpose of doing the depth averaging yourself is that it forces you to pay close attention to the profile you are diving. What the DIR approach does NOT want is a diver who wanders around underwater, not paying attention to depth or time, and depending on the computer to tell him when enough is enough.

The depth averaging approach needs some common sense applied to it, because you can't safely depth average some profiles, and it's not something you're going to learn well on the internet. And one must ALWAYS remember that GUE profiles assume that you WILL do minimum deco; they are not profiles designed to permit a direct ascent to the surface at any time (although most likely, one could do so if it were required in an emergency).

Even a depth averaging approach will not give you the same "flexibility" as using a computer, because the computer is doing a continuously iterative calculation of nitrogen loading. But the models the computers are based upon are mathematical, rather than physiologic, and if you run the edge of the computer, you are running a certain risk of DCS. The GUE approach for recreational diving ends up more conservative than that, but more liberal than the strict "take your max depth" approach for tables which is taught in OW.

Although I'll get laughed at for doing so, I suggest taking Fundies. You'll get a lot more, and more valid information from your instructor than you will get here.

 

[1_T_Submariner]

TandSM, Great post. I was just wondering have you ever checked the DIR Depth averaging against what a computer averages for depth. Just curious on how close the numbers match up.

 

[TSandM]

Actually, I've been delighted to compare my personal depth averaging to what my gauge comes up with for an average depth for the dive. I've never been more than five feet off. But it takes work to be that CONSCIOUS of your dive. You have to check depth and time every five minutes, and remember what you saw, and keep a running tally. I used my computer as a computer for almost a year after I started DIR diving, before I felt confident enough to put it in gauge mode.

 

[SteveC]

Just out of curiosity, how is doing 5 minute mental calculations considered more accurate than a computer?

 

[littlejohn]

I am just starting to use a computer and would like to know what do you put in the log book.
A clean dive on the computer might not look so safe using the Sq tables

 

[nereas]

I use a computer and based on the type of diving I am doing (recreational) and my training thus far, this seems to make sense. In some of the reading I have done thus far, I have run across the DIR perspective and I find some practicality and utility in it.

Having said that, I don't see myself going to overhead enviroments, wreck
penetration, or dives which take me deeper than recreational depths, but I do like aspects of DIR equipment configuration.

In the reading I've done regarding the DIR orientation, the use of computers is shunned for a variety of reasons and I think I understand why - at least from their perspective.

Do DIR folks only dive square profiles? Is there a method to using tables which would allow the apparent flexibility offered by using a computer??

TIA

Mark

If you want to learn how GUE-DIR does things, it would be useful to take their classes. I don't think you would be any worse for the wear, if you did. They emphasize correct weighting and buoyancy, and they teach a number of NDL protocols that you might find interesting.

If you compare their NDL methods with NAUI, PADI, or SSI tables, you will probably come up with similar answers. Then you can decide for yourself which you like better.

I myself have come to trust dive computers, after many years of relying solely on USN tables. The dive computers are safer (allow less N2 uptake) and are more precise than the USN tables, as far as NDL diving is concerned.

When it comes to decompression diving, the story is quite different and more complex; but then, you did not ask about decompression diving.

 

[RS]

One of JJ's "bakers dozen" on computers is that most computers do not handle staged decompression dives well and will give un-necessarily long ascents. And (I guess) some computers will stop tracking tissue loading if you stray from NDL dives or don't follow the "emergency" deco in the computer. I guess some computers do well, but most don't. But I'm not DIR and I'm a newbie so I don't really know this stuff.