tables vs computer

[Newhampster]

I would have more bottom time w/ the computer but would I be able to take advantage of it? As it seems to me that the DM's on vacation send everyone up at the same time.

Most DMs will let you and your buddy stay down longer than the "bunch" if you both look like you know what you're doing and you're both running a computer. Now that isn't always the right thing since I've seen DMs abuse the tables and what my computer says and what my brain says is a reasonable and prudent approach.

Part of the issue here is people don't understand their computer and what the data it presents really mean. How many folks use their computers to really "plan" their 2nd and subsequent dives in a repetitive sequence?

If you blindly follow the DM, drop in the water and watch your computer from time to time, you're not thinking about what you're doing. And that's what's wrong with computers.

Then again, if you don't use a computer, blindly follow the DM, drop in the water and follow the crowd (sorta), you're not thinking there either.

Computers are neither good nor bad. Intelligent use of computers is better than passive use. And computers provide more and better data than tables -- provided you use'm properly and under the right conditions.

Tables are neither good nor bad. Intelligent use of tables is better than just playing follow the leader. Or worse.

Use your head. Computers are a great adjunct. And allow you to be more "aggressive" than if you follow a conservative protocol with tables.

Even if you're smart about all this, don't push your computer's parameters. Don't strive to stay right on the edge of a deco dive. Don't run to the margins. Leave safety room.

And think...

 

[MikeS]

In my opinion, for recreational diving, computers are safer than tables assuming you follow these simple concepts that should be followed using tables anyway.

1. Your buddies computer or table (w/ SPG, bottom timer, and depth gauge) provides redundancy. If you need more redundancy (i.e. decompression, penetration dives) take two computers for redundancy.

2. Dive the more conservative of the two.

2. If either stops working end the dive and surface safely using the one that is still working.

The most likely reason that your computer did not agree with tables is as devilfish said the computer model is basically a massively multilevel dive with separate nitrogen loading calculations for every minute or less.

Contrary to UP’s opinion I do not think that computers inherently rot your brain, although I must concede that they can allow you to become complacent. On the other hand I can download the data from my Cobra and analysis the entire dive to see what I did wrong and what I can do better. It’s great having a chart that shows the speed and stability of your assent was and how well you transition to the safety stop (smoothly or like a cork bobbing up and down). In fact I can view the predicted nitrogen loading for slow versus fast tissue throughout the dive. These are things that are not possible using tables. And the reason I dive is to be one with the fish not to perform mathematical gymnastics.

I always bounce the computer prediction against the tables just to get a second opinion before each dive. This will give you a good indication that the computer is working before you hit the water.

Mike

 

[tinman]

I'm wondering if anyone can tell me if certain computers exactly follow a particular standard eg.NAUI, PADI, ACUC tables. As well which are the most conservation tables, NAUI, PADI, ACUC. I have been using ACUC...

 

[srkdvr]

:mean:

No contest, I would have a computer anyday. I learned diving back in 89 using the U.S. Navy Dive Tables, and up till last year when I got my Uatec Sport Computer filled out my log book after every dive and figured out my next dive and the profile and the max bottom time etc for the dives.
I still keep a very close watch on my dives, depth, time and etc. The biggest thing that has changed is I can not fill out my dive log as before. You see when you dive tables you have to take your deepest point and let that count for your entire dive, granted your deepest point may have been 60 feet for 3 seconds but guess what that is the deepest point. With my computer it I still hit that deep point but it remembers and it calculates that I was only there for 3 seconds not the possible 20 or 30 minutes I was diving. It really depends on how safe you believe computers are, if mine ever acts up I will abort the dive I am doing and go to the surface and of course revert back to tables untill I can figure out what has happen to my computer.
I also would make sure if I was diving using a computer that I would purchase one that was very high on the safety chart cause I really do not want to check out because of lack of good equipment.

Rich :mean:

 

[Uncle Pug]

Originally posted by srkdvr
You see when you dive tables you have to take your deepest point and let that count for your entire dive, granted your deepest point may have been 60 feet for 3 seconds but guess what that is the deepest point.

Do you really have to do that?

 

[Wendy]

I use my tables and the computer in my head (hopefully that one wil never fail). And I learned to do mutli-level dives on tables as well.

 

[Uncle Pug]

Hi Wendy...
I pulled up short when I realized what forum we are in here:
new 2 scuba.

 

[Walter]

Pug,

You do if you are following the tables as designed. There are ways to use tables for multilevel diving, but I don't know of anyone who recommends it. Even you usually give a disclaimer when explaining the process.

tinman,

Computers don't follow tables at all. Tables are based on various models. Computers are also based on models. Some tables and some computers use the same models. I can't tell you which computers use which models.

It's difficult to determine which set of tables is the most conservative because one table will have the shortest NDL at one depth and the longest at another. I lookd at 7 different tables. For single dives the unaltered US Navy tables were the least conservative for all depths from 40 ft to 130 ft (those depths were chosen because all tables covered them), although it tied with PADI's RDP as least conservative at 130 ft. If you are looking for a table that is consistantly conservative for single dives for a variety of depths DCIEM would be an excellent choice. Assigning the least conservative NDL an arbitrary 7 and the most conservative table an arbitrary 1 for each depth, then averaging the results I got some interesting (if useless) numbers. Spencer's limits - 1.8; DCIEM - 1.9; YMCA 2.0; Michigan 2.1; PADI's RDP 3.9; NAUI 4.5 and US Navy 6.9.

Repetitive diving (which almost, if not all, of us practice) is another story all together. The RDP is by far the least conservative for repetitive diving. DCIEM is of such a different format a comparison is very difficult. NAUI is the most conservative in that it requires 24 hours to clear while most of the other require 12 (RDP is 6 & DCIEM is 18).

Which table is most conservative is not a simple question. I don't have a copy of the ACUC tables, but I'm interested in adding it to my collection.

 

[Uncle Pug]

Originally posted by Walter
Pug,

You do if you are following the tables as designed. There are ways to use tables for multilevel diving, but I don't know of anyone who recommends it. Even you usually give a disclaimer when explaining the process.

You are right Walter.... and that is why I pulled up short.... most of my post never left my computer.... but I couldn't resist the teaser to instigate some cogitation

 

[art.chick]

Have been using the HUGI tables (university of Michigan, Karl Huggins) lately. Got them at Chamber Day. They are pretty conservative, but I heard they were based on some comprehensive studies.