This document was last updated on March 15th, 2020
The Fathom CCR breathing loop consists of back-mounted counter-lungs (BMCL), large bore T-pieces, loop hoses, and a Shrimp DSV or BOV. BMCLs provide excellent work of breathing in all positions while keeping the diver’s frontal area free of clutter as well as minimizing their profile. Since a large portion of the gas bubble is up around the shoulders, similar to front-mounted counter-lungs, they have excellent work of breathing in all positions.
The Fathom CCR utilizes flexible stretch hoses in front and more traditional stiff hoses in the rear. The front stretch hoses allow divers to turn their head more easily while the rear hoses offer greater durability in case they come in contact with the ceiling. A Shrimp DSV with bayonet style hose fittings is standard, with the Shrimp BOV a strongly recommended option. The Shrimp BOV not only gives the diver immediate access to their bailout gas without removing the mouthpiece but also acts as a chin rest for reduced jaw fatigue while scootering. The standard T-pieces are large-bore machined Delrin without any low-pressure hoses or fittings since both the diluent and oxygen MAVs are ported directly into the head. A low-profile ADV T-piece is an available option. It’s recommended that the unit be configured with either a BOV or ADV to give the diver a second means of adding diluent to the loop.