PERDIX 2 Ti

The Shearwater Perdix 2 Ti runs a full technical dive on a single AA battery, which is the reason it turns up on expeditions where charging is not an option. A diver carries a spare cell in a pocket rather than a charging dock, and the titanium bezel and piezo buttons take the knocks that come with that kind of diving.

The case is rated to 260 metres and weighs 190 grams at 81 by 71 by 38 millimetres. The 2.2 inch LCD runs 320 by 240 pixels behind toughened glass with an LED backlight. A lithium AA gives up to 60 hours, an alkaline 40, and a Saft LS14500 up to 100. Modes cover air, nitrox, three-gas nitrox, open-circuit technical trimix, closed-circuit fixed setpoint with quick bailout, and gauge, on Buhlmann gradient factors with VPM-B and DCIEM available.

The result is one computer that follows a diver from nitrox to rebreather without being replaced. Air integration is optional and reads up to four transmitters, so a diver can add stage and bailout pressure as the diving grows. The three-axis tilt-compensated compass and strong vibration alerts work the same at 60 metres as at 6.

Three finishes: natural silver titanium, black titanium, and the bronze Journeys Edition. Each ships with a ballistic nylon case, and the recommended cell is the Energizer Ultimate Lithium AA supplied in the box. The Petrel 3 is the larger-screen version of the same platform for divers who want 290 metres and a 2.6 inch display.