Opening the delivery box, I’m faced with the yellow shell of a complex-looking machine, the AP Evolution rebreather unit. This was to be my first challenge being the Scholar, leaning how to dive again.
The difference between closed-circuit rebreathers and the more-commonly used open circuit set-up is that exhaled air in a rebreather system is recycled. Carbon dioxide is removed and a little bit of oxygen is added every so often to the ‘loop’ to maintain the best mix of gas possible at any given depth. Bearing in mind I’ve never attempted any kind of technical diving before, I was concerned that this may be out of my league. Luckily, I had the guidance of Dive Tech legend Mark Powell to help me understand this intimidating device. I was totally spoilt having such a renowned instructor all to myself for four days to complete the TDI CCR Air Diluent Course, and Mark’s patience and thoroughness gave me confidence in my new endeavour of diving as the Scholar.
It was during the pre-breathe, checking all components were in working order before the dive, that I started to become unnerved. It was a difficult balancing act trying to find the minimum volume of air required in the loop without struggling to get a full inhale and without feeling like you couldn’t breathe out a complete breath. This apprehension followed me into the water while we attached out bail-out cylinders and prepared to descend.
Kneeling down into the water, I exhale out of my nose to release gas from the loop to allow myself to break the surface tension of the water and descend. Hovering just underneath the blue side of the waterline I breathe in and out, no bubbles. It takes me a moment to soak in this strange experience.
Mark shows me the okay signal. I resist from sending him a huge smile back that would have broken the seal my lips form around the mouthpiece that prevent the release of air from the loop. So, I send the usual okay signal back… but I’m not just okay… I’m fantastic! Once I achieve minimum volume needed in the loop, additionally with a little bit of air in my drysuit, the buoyancy becomes effortless. Like a hoverfly, helicopter… a fish! We’re solid in the water column. Breathe in, breathe out… you haven’t moved but stayed in the exact same depth. You’re floating in the water column like an astronaut drifting in the vacuum of outer space. Gravity no longer has a hold on you and you’re in flight, ambient pressure diving.
Due to the mechanics of the rebreather there isn’t a build of nitrogen in your system to the same extent as open circuit, which enables the diver to have a much longer dive. No complaints here! Not only that, since there are no bubbles you can get closer to wildlife without scaring them away, which is an invaluable tool in scientific diving and documenting wildlife. So, it’s safe to say that I am converted and cannot wait to take the rebreather away with me on the adventures to come!
A huge thanks to Mark Powell for his amazing instructing and to the Our-World Underwater Scholarship Society and Rolex for helping me make this step in my diving career.