What is a Dive Computer?

A dive computer is one of the most useful accessories available for SCUBA divers, and it is one of the pieces of equipment that can identify a serious recreational diver from a casual one. Few divers who have ever used a dive computer relish the prospect of going back to diving without one.

Dive computers usually come in the form of an over-sized wrist watch, but some are designed to be convenient replacements for the pressure gauge on a regulator. The main purpose of a dive computer is to replace decompression tables, using its on-board timer and pressure gauge to automatically calculate the same information, but with much greater accuracy than would ever be possible with mere pen, paper, and a dive table.

The most basic versions will always display the following information: current depth; maximum depth attained on the current dive; the current "no stop time," or time until a decompression stop is required; total dive time; and the actual local time. Most also have on-board thermometers and can read out temperature, a handy bit of information when diving across thermoclines. Those that are attached to regulators will also read the pressure remaining in the air cylinder, just as the old analog gauge did. Some will also provide data on required decompression stop time, as well as sounding a warning for ascents that are too rapid.

Combined, this accurate and automatically tabulated information is handy for the recreational diver, especially on long, 3 dive days. This is usually the only time where decompression and spending sufficient time on the surface will become an issue for a recreational diver following proper procedure. Dive computers are also of potentially critical importance for the technical diver, who routinely have to plan complicated, multi-staged dive with decompression stops. A mistake in the decompression math can result in a case of the bends, so it is useful to have a computer double-checking those calculations along on the trip.

These devices are so useful that most serious recreation divers don't ask whether to get one, but when. Some choose to wait until after assembling the basic minimal kit of find, mask, wetsuit, and regulator. Others buy it before, assuming they will always be able to rent basic gear, but not a dive computer.

Prices can vary enormously, depending on quality and the number of functions. Wristwatch versions are priced between $300 and $1300, but a good dive computer will typically be at least $450.

About the author: The author of this article, Tatchayapong Dumnurnthum, is an expert writer on dive computers