The Perdix 3 and Petrel 3 overlap substantially in their core diving functions. The main buying differences are housing, display, and rebreather connection options. Both support technical open-circuit diving. A diver does not need a Petrel simply because they dive trimix.
Perdix 3 vs Petrel 3
| Feature | Perdix 3 | Petrel 3 |
|---|---|---|
| Housing | Contoured, injection-molded reinforced nylon | Bulkier machined Delrin (POM) platform |
| AMOLED display | 2.4 inches; 450 × 600 pixels | 2.6 inches; 320 × 240 pixels |
| Published depth rating | 260 m / 850 ft | 290 m / 950 ft for the standalone model |
| Wireless tank pressure | Up to four compatible transmitters | Up to four compatible transmitters |
| External oxygen-sensor connection | No; CCR mode uses a fixed PPO2 setpoint | Available on specific connected versions; not on the standalone model |
Both have toughened glass, titanium bezels, piezo buttons, a digital compass, and vibration alerts with a suitable battery. The Petrel has the larger screen; the Perdix has higher pixel resolution. They are separate models with different interfaces and firmware releases, so their features should not be assumed identical.
Choosing a Rebreather Version
The Petrel 3 SA and Perdix 3 can calculate CCR decompression using a fixed PPO2 setpoint, but neither reads the rebreather’s oxygen sensors.
The Petrel 3 Fischer provides a 7-pin connection for external oxygen-sensor monitoring. The Petrel 3 AK monitor uses a hardwired cable with a 4-pin analog connector. These are different interfaces, not interchangeable plugs. A monitor is not automatically a solenoid controller. Confirm the required hardware, firmware, and function with your rebreather manufacturer.
Battery Choice
The standalone computers use a replaceable AA battery. Shearwater recommends Energizer Ultimate Lithium 1.5V. Vibration requires a supported 1.5V non-rechargeable lithium or 3.7V rechargeable lithium-ion cell. See our SAFT battery guidance for compatibility and limitations; follow the manufacturer’s instructions for OEM rebreather configurations.
DGX recommendation: choose Perdix 3 for its contoured wrist fit and current interface; consider Petrel 3 for its larger display or a required rebreather interface. Check the exact model, rather than applying older Petrel/Perdix comparisons to every generation.
Specifications: Shearwater Perdix 3 and Shearwater Petrel 3.