This document was last updated on May 29th, 2021
The FATHOM MK2.5 CCR features a hardwired Shearwater Petrel 2 handset as the primary display with the new FATHOM Heads Up Display (HUD) as the standard secondary display and a Shearwater NERD 2 as an option.
The FATHOM HUD utilizes a modified Smither’s code to display current PO2 information from all three cells. The HUD is powered by a ½ AA SAFT battery, which is housed in an external battery compartment on top of the head. A piezo switch on the head is used to calibrate and turn the HUD on/off. On startup, the HUD indicates battery voltage through a series of flashes. The ½ AA SAFT battery lasts for 200+ hours due to the incredibly low power consumption. The LED display is reversible so can be worn on the right or left side while keeping proper left to right cell orientation and automatically adjusts brightness to ambient light conditions.
The optional Shearwater NERD 2 replaces the HUD and utilizes a 4-pin AK cable so it can be removed from the head for transport and storage.