Recreational Nitrox Mode

Shearwater's Recreational Nitrox mode was created to meet the needs of serious diving enthusiasts who are either not yet considering technical diving, or prefer a simplified user interface.

This mode is packaged into the Petrel 2 and Perdix.  This makes these devices nitrox dive computer in OC Rec along with Gauge mode, OC tech and OC/CC mode. The various modes are selected in System Setup menu, Mode Setup sub menu.  All of the popular features of the Petrel 2 and Perdix such as digital compass, user replaceable AA battery, 1000 hour dive logging and user upgradeable firmware with Smart Ready Bluetooth interface are available.

The main display of the Nitrox mode is designed to show the most important information for Air and Nitrox diving

Basic Nitrox Dive Computer Functions

The basic dive area shows current depth, in feet or meters (changeable in System Setup menu, Display Setup submenu) and the dive time in minutes and seconds. The decompression area shows safety stops (if enabled), decompression stops, no decompression limit (NDL) in minutes, a nitrogen loading bar graph and warnings for maximum operating depth (MOD) and CNS.

The bottom area is user configurable, but the bottom left will always show the currently selected gas.

Audible alarms are not used in any Shearwater dive computers.  Warnings are depicted by the colour red or yellow and are listed from highest to lowest priority.

Examples of warnings

  • High CNS: Central Nervous System (CNS) Oxygen Toxicity limit reached
  • RED MOD : Maximum Operating Depth (MOD) exceeded. Ascend to shown depth
  • MOD Switch Gas: Maximum Operating Depth (MOD) exceeded. Switch to more appropriate gas (another gas must be programmed and turned on for this to appear).
  • Yellow (Near) MOD: Within 5ft (1.9m) below MOD. Just a notification, no action required.
  • Best Gas: Another gas is programmed that is more suitable at the current depth. Only displays when deco stops are needed.

For more details on warnings, please refer to the Recreational Nitrox Dive Computer Manual 

The OC Recreation mode allows the diver to enter up to 3 nitrox mixes ranging from 21% up to 99%.  The gases are switchable under water and can be added, deleted and edited while on a dive if necessary. The gases in the list are arranged from high to low oxygen content to minimize button presses when selecting a higher oxygen gas.

NDL Planner

No Lock-Out

In keeping with that philosophy, the computer will not lock-out for omitting safety stops or for violating a decompression stop.  In both cases, the Petrel 2 and Perdix as a nitrox dive computer will continue to provide real time information regarding the current status of your dive.

For more details on the operation of the Petrel 2 and Perdix while in Recreational Nitrox dive computer mode, please refer to the Petrel 2 manual in the support section of the website.