Review: Shearwater Petrel Dive Computer

This advanced tech-dive computer is rebreather compatible

Dive computers, it would seem, are about to undergo the same metamorphosis that mobile phones have. For a long time, mobile phones kept getting smaller and cheaper, which put them in the hands and pockets of pretty much everyone. That all changed in 2007 when Apple launched the iPhone; since then, phones have become (much) bigger, more advanced, more expensive, and pretty much all of them now feature touch screens.

Compare this trend to dive computers, which for years have become smaller, more inexpensive, and close to ubiquitous, as we find them on almost every diver’s wrist out there. But the dive computer market now seems to be following in the footsteps of the smartphone market, and the Shearwater Petrel is a prime example. It is larger and more expensive than the most common dive computers, and it is much more advanced. A full-sized, 2.4-inch color screen (can also be set to black-and-white by the user to preserve batteries) means no more scrolling through functions to see depth, temperature, or any other information that some computers hide in deeper menus, due to a lack of screen real estate. If you do enter the deeper menus, via tapping the buttons, you can gain access to information that most dive computers leave out, such as a simulated tissue saturation illustration and current pressure expressed in millibar.

Because of its large size, the Petrel straps on to your arm using two nylon straps with Velcro. Admittedly, the first time I wore it, the computer felt pretty damn big, both in terms of surface area and height. It may have about the same screen size as an early smartphone, but it is a lot thicker, at about 1.3 inches. However, after a little while you grow accustomed to it, and suddenly it feels a little sci-fi to have a large-screen computer strapped to your arm. And the generally compact design seems rugged and durable, so even if this is a pricey piece of gear, I wouldn’t be worried about putting it through the abuse of a wreck or cave dive.

You turn on the computer, and complete every other task, with the two touch buttons on each side, which work just fine through gloves. The screen is quite legible, and even though it provides a lot of information, you quickly learn to decipher it, and can get a complete reading on your dive with a single glance. One function I particularly like is the Time To Surface (TTS), which indicates, in minutes, how long it would take you to reach the surface if you started your ascent right this minute, including all mandatory and optional stops along the way. This is a great piece of information for doing on-the-fly gas management calculations.

Unlike most other computers, the Petrel doesn’t distinguish between recreational and technical dives. In its world, all dives are decompression dives. Recreational dives may only require a few minutes of deco (what we’d call a safety stop), but you may find yourself getting deco time beyond that, even on recreational depths, if you’ve done several dives over the past few days. This also adds an extra layer of safety should a diver accidentally over-extend their dive beyond the allowed bottom time for recreational diving. The Petrel would simply adjust the deco time accordingly, and the diver would be able to easily surface safely. Needless to say, this is meant for use as a safety feature, not a green light for recreational divers to start doing deco diving without proper training.

Power comes from standard AA batteries, which is both a pro and a con. If you run out of power it’s much easier to find AAs than the button batteries that most other computers run on. However, the quality of AA batteries fluctuates more from manufacturer to manufacturer, and the high power demand of the screen means that if you purchase low-quality batteries, you’ll only get a few dives out of a pack. A future version will ideally see some form of rechargeable battery integrated in the unit. You can see the current battery remaining expressed on the home screen by a graphic of a battery that slowly drains as you use the computer, and also expressed in hours of dive time. This is allows you to plan ahead and bring extra batteries when you’re starting to run short.

The Petrel works with all gas mixes, from ordinary surface air to trimixes and rebreathers. So if you’re an advanced diver, or are aspiring to become one in the near future, this computer will definitely suit your needs.

All in all, the Petrel is in many ways a first in the industry, and it reimagines dive computers in a welcome way. Its price tag of just over $1,000 will put it outside the scope of many recreational divers, but for tech and rebreather divers, it is one of the best offerings on the market. And perhaps it’s a harbinger of things to come and soon all dive computers will be based on principles and design similar to the Petrel.