Your computer fails. Now what?

Yes, we know. You meant to change that battery before your next dive trip but you didn’t. Or maybe you didn’t do as good a job as you should have in rinsing your computer after each dive and, as a result, the transducer port is clogged with salt. Or maybe it was some other reason entirely.

Whatever the cause, your dive computer was working and now it is not. If you discover this fact before the first dive of the day, you may be in luck. As you have no residual nitrogen in your system from previous dives, all you need to do is get your hands on a working computer and use it.

But what if your computer fails between dives? What are your options now? That’s what we will look at in this article.

What not to do at this point

Let’s be up front here. If your computer fails between dives you are most likely out of the water for the rest of the day. There are things divers will sometimes try in order to keep diving. All of them are equally stupid and merely increase your chances of getting bent. Let’s take a look at each of them.

Rely on a buddy’s computer

You might be thinking, “My buddy and I stuck together on all of our previous dives. Same depths. Same bottom times. Same profile. So long as he and I stick together on subsequent dives, I should be okay as long as his computer says we are.” Guess again.

Unless your buddy was strapped to your wrist for the entire dive, there are going to be differences between his dive profile and yours. Even slight differences can result in significant disparities in nitrogen uptake and release. So your buddy’s computer may say everything is fine but that doesn’t reflect what may be happening in your body.

Borrow a computer from someone else

This is even dumber than relying on a buddy’s, especially if that computer has not been in the water for prior dives. If a buddy’s computer is incapable of reflecting what is happening in your body, a computer that was with someone who wasn’t even part of your team has an even greater disparity.

Further, if the computer you borrow has no memory of residual nitrogen from previous dives there is simply no way it can keep you out of trouble. This is just asking for it.

Just trust to luck

Then there are the divers who figure, “I didn’t go that deep. I didn’t stay that long. As long as I take it easy I should probably be okay…right?” Well, in the words of the famous Sam Elliott meme, “You’re a special kind of stupid, ain’t you?”

Can you fall back on dive tables?

The answer here is, “It depends.”

If you are willing to wait until your body has completely offgassed then, yes, you can switch to dive tables. This will most likely mean staying out of the water for the rest of the day.

If you want to use tables to continue diving on the same day there are four conditions you must meet.

What are these four conditions?

You must have a set of dive tables and remember how to correctly use them.

You must have a way to accurately track your depth and time. This will most likely be another dive computer but you will need to ignore what it is telling you about your nitrogen exposure and use it as a simple bottom timer.

You need an accurate record of the depths and times of your prior dives, including their starting and ending times.

You need to be able to plot your prior dives on your tables to ensure they fall within the dive table’s no-decompression limits.

Let’s face it: The odds of those four conditions being met are pretty damn slim. Even if you are willing to wait until the next day to resume diving, you will still need to meet the first two conditions. This is also when you will discover just how limiting dive tables are.

As usual, prevention is the only real solution

As you should realize by now, there are few practical workarounds to a computer that fails between dives. You are far better off preventing the problem in the first place. To do so:

Replace your computer’s battery as soon as the Low Battery indicator appears.

If going on an extended dive trip, replace the battery before leaving home. If it fails mid-trip, the odds of finding a replacement may be slim.

Rinse your computer thoroughly after every dive. Do not give salt, sand or sediment a chance to build up.

Are backup computers a good idea?

They sure as Hell are. Having a backup computer will help ensure you can continue diving even if one of your computers fails.

Of course, having a backup computer available is only viable if it accompanies you on every dive. Otherwise, it will have no memory of the residual nitrogen in your system from prior dives. Your backup computer must be strapped to you or your gear, not sitting topside in a gear bag.