The Fathom CCR is designed to be the simplest and most intuitive closed-circuit rebreather for long-range cave exploration.
Several years ago, as our dives became increasingly deeper and longer duration, my fellow Karst Underwater Research (KUR) divers and I recognized the need for a new closed-circuit rebreather (CCR) with excellent work-of-breathing and long scrubber duration that would stand up to the rigors of cave exploration. Semi-closed units, such as the Halcyon RB80, were considered, but we ultimately concluded that the improved work of breathing and greater efficiency of a CCR outweighed the added complexity for many of the dives being conducted. While there were a number of capable CCRs on the market, all had one or more features that either eliminated it from consideration or would require costly modifications to fit our purposes. The last thing we wanted was to spend thousands of dollars on new units only to strip them down and spend thousands more retrofitting them with different parts. The short list of desired features included:
Unable to find an existing unit that met these requirements, I started to design what would eventually become the Fathom CCR. There are no easy decisions when it comes to rebreather design and every choice, every dimension, every o-ring, was debated endlessly with fellow KUR divers. Andy Pitkin, Brett Hemphill, Ted McCoy, Kevin Leonhardt, and Jon Bernot were all heavily relied upon during the design process. I am grateful to them for tolerating the endless phone calls and hours of discussing minute details. Ultimately, the final decisions were mine and my background as a Hogarthian/DIR cave diver guided me towards simplicity and functionality.