Dive Computer: Everything You Have Ever Wondered About It

A good dive computer is life insurance for a scuba lover. We don’t know if you’ve ever used a decompression table after getting your Open Water certification, although you should. What we do know is that diving computers have managed to make recreational divers practically forget them. Already, computers automatically calculate how long we have left under water or how long a decompression stop should last and how deep to do it.

However, despite being extremely useful, we still meet divers who do not carry a scuba diving computer. It happens even when they have booked double tanks every day in a row for a week. They trust the dive computer of the dive buddy or the divemaster. But what happens if there is an unforeseen event and you find yourself far away from your guide or worse, alone?  Others rely on renting one from the dive center, assuming that option is available, although not all have them. So, it is better to have your own scuba diving computer.

But, before buying your dive computer, read the article that we have prepared for you.

Table of contents:

1. What Is a Dive Computer?

A scuba diving computer is an electronic device that provides real-time dive information.

It takes into account the time and the depth reached on a dive. Its algorithm applies a decompression model and estimates the amount of dissolved nitrogen in your blood for these parameters.

2. What Does a Dive Computer Do?

A dive computer informs about:

• the current depth,
• the maximum depth reached,
• the elapsed time of the dive,
• dive time limit without decompression stops,
• maximum ascent rate,
• time and depth of decompression stops, if necessary,
• water temperature,
• surface desaturation time,
• the time before flight,
• visual and audible alarms (not all include these features)
• battery charge indicator
• log of all dives.

The features of a scuba diving computer may exceed those listed. For example, it may also adapt its measurements to the air mixture(s) used, Nitrox, Trimix, Heliox, gradient factors, different algorithms, etc.

A scuba dive computer includes an algorithm, usually based on the Reduced Gradient Bubble Model (RGBM), that calculates the nitrogen saturation in your body as a function of time and depth. Then, it estimates the maximum ascent rate to safely release the absorbed nitrogen, as well as the conditions for decompression stops.

A scuba computer also calculates the amount of residual nitrogen in your body after the dive and deduces the minimum duration of the surface interval between dives or the time you should wait before flying.

3. How Accurate Are Scuba Computers?

All in all, a dive computer takes into account: time, depth, the air mixture used, the temperature of the water, the number of dives, and the surface interval between them, but it will also take YOU into account.

A scuba diving computer monitors a person’s underwater activity under specific conditions.

You don’t dive the same way as your buddy, so you can’t rely on the data his computer gives you on the same dive.

–                Every time he sees a critter, he chases it to the bottom, and you are very consistent.

–                She isn’t as neutrally buoyant as you are and often ascends without realizing it.

Little things like this make all the difference.

Since it also keeps track of the dives, we could say that the dive computer learns and provides more accurate data to its owner the more he uses it.

Okay, a diving computer is not foolproof. It does not know some parameters which affect decompression: your weight, your stress level, if you have slept well, your hydration level, or your physical condition, but it does know how you dive and where you dive.

4. Why Do Divers Prefer Computers Over Dive Tables?

The reasons why divers prefer diving computers to dive tables are their benefits for diving. These have made them an indispensable part of the equipment.

1. With a scuba dive computer, you forget about calculations. They are essential when using dive tables.
2. Diving computers eliminate human error, common when using tables. You will know your time limit for the dive with no decompression stops to the second. You will never descend more than you should and have more controlled ascents.
3. Dives get longer because dive tables are very conservative and generalist. They calculate the entire dive to maximum depth. However, a dive computer adapts to you and your depth differences.
4. You can use other gases.
5. You will have an accurate dive log. In addition, you can download the data from your dive computer to your laptop.

5. How Do You Read a Dive Computer?

1.   Read the instructions, and if you are still in doubt, download the dive computer manual from the manufacturer’s website.

2.   Set up the computer: date and time, metric or imperial system, fresh or salt water, etc. You need to be able to see the numbers. If you have vision problems, wear a prescription mask or contact lenses.

4.   Check the scuba diving computer before each dive, the battery charge, and if it works properly.

5.   Each diver should carry their own dive computer, and if the data differs, follow the indications of the most conservative one.

6.   Computers turn themselves on. Provided it has sufficient battery power when the diver reaches a shallow depth the computer turns on.

7.   Reads data from the vertical to avoid mistakes with digital numbers.

8.   Interpret the data correctly.  Take care to understand how the computer presents information. A number doesn’t mean anything if you don’t know what it´s telling you.

The decompression time will appear as a countdown clock indicating the number of minutes remaining to the limit. This number will decrease with increasing depth and time elapsed during the dive.

The ascent rate is represented differently depending on the scuba dive computer model. If the diver exceeds the ascent speed rate, the dive computer starts to alarm.

Two numbers indicate decompression stops. The first one tells you the depth at which you should make the stop. The second is a waiting time countdown before you can ascend again.

9.   Make periodic checks during the dive. Just as you check your tank pressure, check your computer. Many computers can integrate this data.

6. What Are the Different Types of Dive Computers?

There are basically 3 types of dive computers:

• The wrist ones, easy to monitor by less experienced divers
• Console dive computers are usually integrated with the pressure gauge and have a larger display than the others.
• The computers integrated into the mask, are much less frequent, but they allow the diver to see the data just by looking down.

 7. What Is the Difference Between a Scuba Diving Computer Watch and a Dive Computer?

A dive computer can be a wrist-mounted computer, although it can also be integrated into a console next to the pressure gauge and compass or even on the regulator.

A scuba computer watch has a wristwatch size. People use them out of the water. Even more, many non-divers use scuba dive computer watches.

8. How Much Does a Scuba Computer Cost?

The price of diving computers varies from 224.66 USD for the cheapest dive computer to over 2,000 USD for the most expensive models.

We have to say that the most economical scuba computer already offers the necessary features for recreational diving.

9. Which Dive Computer Is Best?

If a cheap computer already includes all the features a recreational diver needs, what makes it more expensive? It depends on whether:

It is a dive watch computer.

It has a user-replaceable battery or you should send it to the manufacturer.

It has audible and visual alarms or only one of these two options.

It can communicate with transmitters. Transmitters are devices connected to the tanks that send tank pressure data to the dive computer.

It has a compass.

It is an air-integrated dive computer

It has downloadable information or not.

It is a dive computer with BlueTooth functions

It provides information on different air mixtures.

It integrates several algorithms.

It is a scuba dive computer with GPS

It has gradient factors.

It is a hand-up display integrated into the diving mask or carried on the regulator.

10. Features of the Best Dive Computer for You

Readability. It is no use having the best scuba diving computer in the world if you can’t read it. So, make sure that the numbers have a good size, that the screen offers a defined contrast between the numbers and the background, and if possible, that the screen is backlit, in order to see it better.

Easy to use. Read the dive computer’s reviews of other divers on the ease to set it up. In the middle of the “plug and play” era, a computer with a steep learning curve is not useful.

Another thing, do you wear gloves when you dive? Well, keep that in mind when choosing your scuba computer. Look for one with large, well-spaced buttons.

Features. Choose a scuba diving computer that is suitable for the type of diving you’ll practice. Air mode is the most common, but you may dive with Nitrox, so make sure it offers that option. Technical divers use Trimix and free divers also need a scuba diving computer to suit them.

On the other hand, make sure that the dive computer has the measurement options that you really need, there is no need to buy a high-end computer if you are not going to take advantage of it. Technical divers have very different needs from newly certified divers. Did you know that they need two diving computers for each dive?

For many divers, being able to change the battery themselves is an indispensable feature. If you are one of them, look for a dive computer watch with a user-replaceable battery. Otherwise, you won’t be able to touch it, and if you do, you will lose your warranty.

11. How Long Do Diving Computers Last?

In the 1990s, dive computers offered a lifetime warranty. Yes, they did as you read it. They used to have a lifespan of 7 to 10 years, and the manufacturing company took care of everything: battery replacements, repairs, replacements, etc.

Today, changing a battery can cost 250 USD, including shipping.

In addition, all electrical devices have short-programmed obsolescence. I’m not just talking about scuba diving computers. I’m talking about cell phones, laptops, or video game consoles. The new model with the latest technology comes out just when the old model is still gaining market share.

Scuba diving computers are affected by this reality, and it is weird to find any model that offers a warranty longer than 2 years. Today, the average life of a dive computer is 4 years.

12. Which Of the Following Is Part of Proper Care for My Dive Computer?

What you can do:

– Rinse the dive computer in fresh water at the end of the dive.

– NEVER try to open it, unless it is a scuba computer with user-replaceable batteries

– Keep it away from direct sunlight so as not to damage the digital display.

– Protect it from shocks and chemicals.

– Store it in a cool, dry place.

– Make the revisions that the manufacturer indicates (every two years or after 200 dives).

– Go to the manufacturer or distributor if you see mist, scratches, cracks, or other defects on the screen.

What the manufacturer should do:

– Battery changes.

– General overhaul of operation, seals, and sensors

– Change of seals and lubrication

– Tightness tests.

Do you have any other questions about the dive computer? Contact us.