- Dive Computers for Demanding Divers -

Wellington Scuba Diving-Shearwater Petrel 2 OC CC

Petrel 2

I bought my Shearwater multi-gas computer to interface with my KISS Classic re-breather. However quite often I dive it using SCUBA. When I compare it to previous multi-gas computers I have owned I am amazed. Switching gases above or underwater is the easiest I have experienced. The Petrel 2 can be programmed for 5 OC and 5 CC gases. All functions are controlled by two touch buttons. These are reliable and can’t jam.

The Petrel 2 has a lot of menu functions, but there are very few you need on each dive. The process is easy as the menu is scrolled by one button and is selected by using the other button. It has big graphics and is easy to read under water. It is back lit and that brightness can be controlled. I was diving deep, using trimix and doing two gas changes and knew instantly which gas was which. The battery is user replaceable, and you can choose from several different types. The electronic compass is a real must for the Rec and Tec diver.

The switch from OC to CC is really easy. It monitors the CCR oxygen sensors by cable, or it will calculate deco using a set PPO2. Any data that appears incorrect to the computer will result in that data being highlighted in bright colours. All data is very easy to read. Decompression obligations show: CNS, ascent rate, TTS, stops and time required. Warnings are flashed! Download is via Bluetooth.


The Perdix comes with or without an air integrated function. The AI function will allow you to monitor your gas duration based on your current depth and breathing rate.  The Perdix does not come with a Fischer connector so cannot be used to monitor actual PPO2s on a CCR. It can however be programmed for a fixed CCR PPO2.

The Perdix has identical firmware and features to the Petrel 2 including the compass. Improved functions include: double O rings on the battery cap, integrated bungee mount holes, lower profile but has improved colour display and 30% longer battery life.

Wellington Scuba Diving-Shearwater Perdix Dive Computer
Wellington Scuba Diving-Shearwater NERD


(Near Eye Remote Display)

Now we have the ultimate Heads-up-display as well. Shearwater have produced the NERD (Near Eye Remote Display), a fully self contained CCR HUD. It attaches to your CCR head by Fischer cable and has a user replaceable battery.At eye level you get real data such as PO2, CNS, depth, time, gas, required stops and deco obligation. This image is like reading a Petrel that is about 36cm (1 ft) away.

The Perdix has identical firmware and features to the Petrel 2 including the compass.This is a great tool for safe diving as it gives you hands free eye level monitoring. If you need a more conservative reading, these computers will allow that. Ideal set-up is a NERD at eyelevel and a Petrel backup on the wrist. These are the computers to take you safely into CCR tech diving – and get you safely back home again. 

Tony Howell TDI:IT