Ok, it’s time to add another tool to the toolbox. Just like putting the hammer down and investing in an air nailer, I got tired of the limitations of open circuit and wanted to take the leap. Time for some closed circuit action. Or, at least that’s the conversation I had in my head.
My first question was motivation. Is it really cost effective, time effective, and most importantly, useful to dive closed circuit? Not only that but is my motivation well-intended? I had heard the stories of bad motivations when it came to rebreather diving – people without the general dive experience, trying to dive CCR to get as deep as possible, or people pushing their overhead experience because they had a shiny new rebreather.
With almost all of my tech diving friends having rebreathers, I had heard the pitch a dozen times. I’d dove in mixed teams and seen the substantially lower deco time for certain depth/gas profiles. I had a pretty good grasp on the benefits of diving a rebreather but just hadn’t pulled the trigger. My motivation was logistical. Most of my fun diving is done a few hours from home, and there’s an unnecessary amount of time wasted on these trips getting in and out of the water, getting gas fills, etc. That’s what originally pushed me to learn to deco dive. More time on the wreck with less ladder climbing. Now, I was applying the same logic to investing time and money into diving closed circuit and, at least to me, the motivation was righteous.
With the motivation ironed out, it was time to pick a unit.
I decided to ask for some opinions regarding that. My biggest take away from that was the only thing more bountiful than units to dive are the opinions held by rebreather divers. Holy moly I got a lot of info. Some of the information was using terms I wasn’t even familiar with yet which made the decision even harder to process. So, like most decisions I make, I sat down with some biscuits and gravy to think it over. I made my decisions on three points:
The unit was a recognized unit with TDI and had undergone 3rd party testing.
My co-worker and friend is an instructor on the unit so I knew I’d get a high-quality course from a person I knew.
With all of my deco and cave dives being in the sidemount configuration I decided to stick with what I knew and dive a sidemount unit.
So, with those 3 factors in place, I got started. It’s common for instructors to issue a warning before the first rebreather course: “You’re going to learn to dive again”. We typically brush statements like this off because we think we’re too awesome to be bad at anything. From time to time it’s nice to be proven wrong though.
Buoyancy is totally different but that’s expected. My instructor gave me plenty of information on that from the start. No more compensation with larger or smaller breaths. After a few minutes, and some practice ascents, it’s about as easy as OC.
Trim was also different, with the unit weighing out differently than just a set of cylinders. That just took some adjustments and time.
The academic aspects from the TDI Generic CCR online course, as well as the class lectures, isn’t much different than what I had learned in my deco class, but the application, or methods, were applied differently. It takes some time to stop and absorb this information.
So, what was it like from my perspective as a student?
While different and challenging in its own ways, a CCR class teaches you how to use a new tool, that’s it. With a good instructor, the complexity of using the unit becomes second nature.
One of the great joys of teaching is seeing a student “get it.” One of the great joys of teaching CCRs is seeing things truly click for a diver on the unit they’ve chosen. Unlike open circuit, however, this can sometimes take a while.
Experience may not be your friend
The typical CCR student comes in with experience. Some, quite a lot of experience. This can sometimes be a detriment when the new CCR diver doesn’t recognize that when they get in the pool for their first CCR dive, they’re a brand new diver doing pool dive #1 – not the best technical diver ever born with thousands of logged dives. With the mindset of “I’m a total noob,” the mastery of buoyancy control (and the unit) progresses very quickly though. The experience pays off as the diver masters new techniques to accomplish prior learned skills. Without that mindset, divers can quickly become frustrated as they bounce off the bottom of the pool and then magically float to the top, all while trying to breath to control buoyancy.
With open circuit, if you’re breathing off your regulator, everything is typically going well with regards to your gas supply and quality. Problems are obvious and readily recognized. With closed circuit, nothing could be farther from the truth. Many of the problems encountered with rebreathers are insidious, giving little warning. Being fastidious about monitoring your PO2 and how you’re feeling must become second nature.
This also applies to caring for the unit. A quick rinse with a hose may suffice for a set of doubles, but quite a bit more attention must be paid to a CCR to keep it functioning properly. Teaching the new diver this habit can take time and repetition. No matter how long the day was or how tired I am at the end of the day, I need to set the example by properly caring for my unit as I work with the new CCR divers to take care of theirs. Along with that is developing the new CCR diver’s use of checklists as part of their routine.
Diving with problems
Perhaps the most difficult skill to teach in the CCR course, especially a diver’s first CCR course, is the mindset of not diving with problems. Things like a sensor failing to calibrate, a very small leak in a hose or fitting, or other issues, are very tempting to enter the water with. We see it all the time on single tank sport dives – the small stream of bubbles streaming out behind a diver due to a spent valve o-ring. We learn early on to dive through those small problems rather than not diving. With technical diving in general and CCR diving in particular, adopting a similar mindset leads to a whole host of potential problems.
It’s vital to develop the new CCR diver’s ability to call the dive before getting in the water if needed. A mindset of problem prevention must take priority over that of problem management, else normalization of deviation can compound problems beyond a diver’s ability to solve them. Developing that mindset in the first rebreather class is possibly one of the most important tasks for an instructor.
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