Diving Fundamentals: The Dive Computer

The dive computer has become an essential piece of equipment, and yet many people don’t have one, refuse to rent one or attempt to share one. Here’s why you should have your own dive computer.

One of the key recreational diving rules is to keep track of your body’s exposure to nitrogen, to ensure that you stay within safe limits. Dive tables are still taught in many instances as a foundation for dive planning, but as technology has advanced, the dive computer has become an essential piece of scuba equipment.

Dive computers monitor your depth, duration of dive and movement underwater using a series of algorithms. You can also use them to keep track of your surface-interval duration and to plan the next dive. Every instructor and dive guide uses one. And, if you’re doing multiple dives or simply looking to maximize your bottom time, they’re an essential piece of safety equipment. In fact, most reputable dive centers and liveaboards insist on them. Here’s why you should buy or rent a dive computer for your next dive trip, and some common fails to avoid.

Benefits of having your own dive computer

Maximize your bottom time

Traditional dive tables are based on a square profile, assuming that you’re going to spend your entire dive at the planned maximum depth. Dive computers, by contrast, sample your location in the water every few seconds and calculate your precise nitrogen exposure, allowing you to multilevel your dive and extend your bottom time.

Make planning easy

Dive computers also take some of the work out of dive planning and make your life easier. Many models have a planning function, allowing you to select the length of your surface interval and the planned maximum depth of your next dive. They can also give you no-stop times for various depths, based precisely on your profile from previous dives. This means you can choose the best time for your next dive and if you’ll have enough time at depth to safely achieve your dive objective.

Track your ascents and safety stops

As you ascend at the end of your dive, your computer will track your ascent rate. It will notify you if you’re exceeding safe limits with a series of beeps. Once you hit the proper depth, it will prompt you for safety stops and notify you when yours is completed, even recalculating and adding time if your ascent has been quicker than anticipated.

Common Fails

Sharing dive computers

On dive boats you’ll sometimes hear someone say they’ll just share their buddy’s dive computer. This is not a sensible idea. Dive computers are designed and built to calculate the wearer’s profile and exposure only. Your profile — unless you’re holding hands for the whole dive — will inevitably be different than every other diver’s in your group. Those small differences in depth, time and ascent rate can multiply over a few days of diving. This can leave you with a greater nitrogen exposure than you bargained for.

Diving blind

Some divers opt to follow the guide rather than taking their own computer. This is even more potentially dangerous than sharing with your buddy. Dive guides are there, as their title implies, simply to guide you and bring you back to the boat.

Instructors, divemasters and guides often move from group to group as logistical demands dictate. In some instances, they are even breathing a different gas than the customers they’re leading. Their dive profile for that day or week is inevitably very different from yours.

As qualified divers, guides expect you to notify them at agreed upon gas-consumption points. Let them know when you’re at half tank or low on air. They also expect you to notify them about your no-stop limits. This is your responsibility.

Dive computers have been nothing short of a miracle of modern technology when it comes to safety in our sport. They’re also relatively inexpensive to buy or rent. Be responsible, dive safely and ensure that you use a dive computer on every dive.

By Marcus Knight (The Scuba Monkey)