Capt Jim Wyatt
Hanging at the 10 Foot Stop
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CCR Cave - Why?
Over the years I have heard cave divers complain to me that since they were certified cave divers and certified CCR divers there was no reason to take a CCR cave class. They complained that the class is just a “money grab” by CCR cave instructors.
Recently I was hired to conduct a CCR cave upgrade course by two cave divers who have been certified as open circuit cave divers for over 20 years and who were certified as CCR divers around 18 months ago. I determined by the end of day two that they were not ready to be certified as CCR Cave divers and I told them so. We continued to dive the next day to work on their skills and fix the problems.
The CCR cave upgrade class was designed for divers who are both certified as OC cave divers and CCR divers. The course is designed to help divers integrate their CCR into their cave diving repertoire. The class, by standards is a minimum of three days long and requires a minimum of 300 minutes cave bottom time for completion/certification as a CCR Cave diver.
Other requirements are to conduct exits in OC bailout mode, SCR mode and to refresh cave diving skills such as complex navigation.
Instructors must cover the CCR-related skills as outlined in the CCR Cave Diver course standards. Additionally, at their discretion, instructors may include any skills from the Apprentice and Cave Diver courses to ensure student mastery of the material.
Divers must determine their OC SAC rates and exiting swim speeds in order to know what their open circuit bailout volume requirements actually are.
Consider a cave penetration distance of 2000 feet in 100 ffw with an OC sac rate of 0.75 ft3/minute while swimming 50 feet/minute. If the diver is using two steel LP 50’s pumped to 3300 psi does the cave diver have adequate bailout? The answer is a resounding NO. The volume needed for this exit at max penetration is 118 FT3 and if we multiply that by a factor of 1.5 (As NSS-CDS standards require) the volume requirement is 177 FT3. The LP 50s have 125 FT3 in them when filled to 3300 psi.
One of the caveats to CCR diving is that if you are going to use a CCR you should use it exclusively as your GO TO scuba gear. This is because the skill sets used for CCR diving can and do degrade over time unless practiced routinely. Some may argue that point, so be it.
The divers I had in this class had never thought through the finer points of OC bailout. Specifically, they had never actually calculated their OC bailout volume requirements for dives they were doing. When I did the math with the students, they realized that they had been going further in caves than their bailout volumes dictated. It was an eye-opener for them.
When we attempted a 1000-foot exit using SCR mode (as required by NSS-CDS standards) these divers were unable to maintain buoyancy and frequently lost control of their buoyancy and trim. Divers should have mastered SCR mode in open water before practicing it in the overhead.
We do teach SCR mode in an entry level rebreather class at this point, however there are those who have stated that we can forego that skill in the entry level classes because we simply teach OC bailout if the CCR fails.
When we did a complex circuit, installing jump lines, and markers in a relatively small tunnel with a mud bottom and no flow the divers did not have complete control of their buoyancy and trim. Once again they did not perform like the good cave divers they look like while on OC.
After 445 minutes of bottom time over three days, we were able to get these divers somewhat more squared away on their CCRs in the cave. Everything started getting better.
When the divers return in January 2025, we will work more on them integrating their CCR into the cave environment and hope to certify them as NSS-CDS CCR Cave divers.
