computers and dive tables

[mudchick]

It seems a natural progression that if one really enjoys diving and plans to continue with the sport, one purchases a dive computer.

My question is after buying a computer do you ever look at your dive tables again? Why or why not?

Since I started using my Sherwood Wisdom I rarely if ever use my dive table. Am I missing a part of the post-dive process by sticking with the computer?

 

[famous58]

No. Just be smarter than the computer and you'll be fine. I've seen people look at their computer after a 60ft dive and say, "oh look, I can go to 120ft for 8 min!".

 

[ApexLongimanus]

Yes, I do look at tables for basic dive planning.

 

[Kunk35]

As a recently certified diver, we were taught to use the tables alot more than we went over the computer. In fact, we really didn't cover the computer at all. I assume due to the vast differences in the specific computers.

We used the tables post dive to plan our next dive and surface interval.

I'll get back to you as to whether I start relying more on my computer. I need a few more dives to be able to answer that...

 

[cummings66]

It depends on what I'm doing as to whether I use my tables at all.

What you need to realize is that if you use a computer and you dive to the NDL or very close to it your tables are USELESS. If your computer fails you done diving. The entire reason for using a computer is to get a benefit out of it, one benefit is longer bottom times. To get them you should understand how a computer is doing that, it's not measuring anything for you specifically, but it is calculating on the fly your dive profile. You could do the same thing if you chose to.

The reason the computer will allow you longer times underwater because it's looking at your dive profile and making calculations based your depth right now instead of something 20 feet deeper. So just because you hit 100 feet for 2 minutes and then come back to 30 feet for 35 minutes doesn't mean your nitrogen levels are maxed and the computer figured that out by doing the math. Using tables you plan on the deepest and the entire dive is assumed to be there, unless you use a wheel.

So you can see that by using the computer on the dive described above allows you to dive it, yet if you go strictly by tables it's not a dive you can do. It's worse if you dive Nitrox and have the O2 clock as well as NDL to keep track of with tables. Now you can plan the dive with a wheel and do essentially the same thing if you want, but the freedom of depth is limited by your plan, i.e. dive the plan. The computer allows you the freedom of plan flexibility, if instead of the agreed upon 100 feet for 5 and 50 for 20 I decide that there was more to see at 35 I can do it and stay longer. Using a table I'd have to cut the dive shorter.

I might use tables to initially plan a dive, and during the dive we try to stay close to the plan, but our plans always reference the computer as well. In other words, if we plan a dive to 100 feet and somebodies computer says go up before our plan said we should then we go up. How far depends on what we've seen on the way down and what we discussed in the planning.

Computers can allow you to get careless and you'll stop planning dives, but I'd suggest you keep the noggin in the loop and planning phase for practice. Just remember if you exploit the computer's benefits then you may as well leave the tables home because they're now useless to you. If you dive per the tables then you may as well leave the computer home because it's useless to you. See the contradiction?

The middle ground is where I'm at. I like a bit of flexibility within limits and I like the dive profile the computer keeps track of. It's interesting to match it's peaks with the rocks you go over...

 

[NYHippo]

I have to admit, I never look at the tables. I do plan out every dive using HLPlanner. I usually do 2 dives a day and I memorize my plan, including turn around time and turn around pressure. I then dive the computer, but stick to the plan no matter what the computer says. The computer is in case of failure to stick to the plan, for whatever reason.

 

[CJ Waid]

I will never use a dive computer, well at least I don't plan on it. I like looking at the dive tables personally. I think it is good to use the dive tables so you get intimately aquainted with the limits, i also use the Navy dive tables, because I am very healthy, and I want to know what the limits really are. Not suggesting anyone do this, it is not a good idea, stick to what you learned in your certification course, bla bla bla etc. etc. etc.

 

[Reef Man]

I also have the wisdom and I do rely on it for the most part...I do tables also just for completing my logs and a fail safe.... I have been told that it is over kill but... I am a fairly new diver...so I may do this for a while!!!

 

[miketsp]

It's always nice to have a good idea of what your computer is supposed to give you.
You may just have forgotten to set the EAN mix correctly or revert it to air....

And since many of my dives are square profiles anyway on wrecks then they line up pretty well.

 

[Meng_Tze]

Just remember if you exploit the computer's benefits then you may as well leave the tables home because they're now useless to you. If you dive per the tables then you may as well leave the computer home because it's useless to you. See the contradiction?

I disagree here. Both the tables and computers are based on the same thing. While there are different decompression models, lets assume that we use the same model for a table and encoded in a computer.

You are right that the computer gives you up to date information about where you are in the dive. But look closely at a computer and a table of the same model..... you will be 'surprised' to see that they will be about the same. What basically happened is that the manufacturers have encoded the same model as you have on tables into the computers, sometimes with an even bigger safety margin.

Tables and computer models will give you the same profile given the same decompression model. (and I am not talking about a few minutes here or there)



PS of course if we are comparing a USNavy table with a Buhlman-C computer, you will get different profiles. But then we are comparing Oranges to lemmons: both citrus fruits, different experience..