After many years of scuba, one member's experience of going over to 'bubble free' diving :-).
After years of wanting, I finally gave in to the inevitable after listening to two diving friends (now resident in Oz) who had recently bought a pair of the yellow boxes. A few dive buddies have had rebreathers for years, but I was never in a position to buy one. Now the market is maturing and 2nd hand boxes can be bought at more reasonable prices (new ones are still eye wateringly expensive), I had to give it a go!
Why? It is something new and different and a challenge, I've been a diver and instructor for more than 15years and a mixed gas diver since 2005 and I have always enjoyed exploring new and different aspects of diving. The technology is advancing and I think this is where diving is going and I want to be part of it and understand it.
Plus - warm air to breathe - nice, no bubbles so you can sneak up on the wildlife and take photos - nice, optimum nitrox mix at all depths for maximum no stop time/minimum deco stops - very nice, 3hour+ dive from a couple of 3L cylinders, regardless of depth - what's not to like?
Well - cost of course, first buying the thing and then keeping it in condition. If you are regularly diving on trimix it will eventually pay for itself in reduced trimix bills (£10/dive instead of £100), but for most dives it is going to cost a bit more per dive to run, so I am not kidding myself there will be any financial payback. Also you must treat it with care and be meticulous in your dive planning and dive skills or it will bite you (maybe even kill you).
So enough about rebreathers, you proably know already (or don't care), what was the course like?
Day 1: Theory and Pool Session
Robin Hood watersports was our venue for Day 1, I quickly realised I had dived with my fellow student Simon before (diving is ever a small world) so we were going to get on fine. We proved our credentials (you must be a Sport Diver or equivalent with a Nitrox qualification to start the CCR course), located the coffee machine and settled down for the traditional death by powerpoint (OK, it was actually interesting & important) but there really is a LOT of theory - fortunately some of it will be interspersed with the rest of the course so our brains won't be compelete mush just yet. After a couple of hours we headed down to the pool for our first practical session on how to assemble & setup the units.
From there - early lunch and then back to learn our pre-dive checks before finally getting in to the pool. Demonstrate, Repeat, Consolidate, next skill, demonstrate, repeat.. feels odd to be a student again! Predicably got various things wrong and backwards until enough repetition began to drum the skills in. What do you learn?
First - basic buoyancy control, because it just doesn't work like open circuit.
Next - opening and closing the mouthpiece and letting go of and recovering the mouthpiece - it is the CCR equivalent of DV recovery really.
Bailing out - which is just closing the mouthpiece, chucking it away and getting your open circuit regulator in your mouth - this is your first response to an emergency, get some safe breathing gas and work out what's wrong.
Diluent flush - how to purge the gas out of the breathing loop and replace it with fresh air. This is an essential skill, good for checking or correcting a bunch of problems including...
Too much oxygen - do a dil flush then find out what was wrong,
Too little oxygen - do a dil flush then find out what was wrong,
Cells can't agree on how much oxygen there is? Dil flush to check which (if any) are correct, the list goes on.
Eventually we round off with rescues - including how to do an effective controlled buoyant lift and tow with AV when there are big fat hoses and counterlungs in the way.
Pool session over we return to the classroom to continue with theory and plan out the rest of the week. Tomorrow - Capernwray and our first real, openwater dives on closed circuit.
Day 2: The weather was lovely but for me, the rest of the day was frustrating. First - awful traffic on the way over meant I was late, then an overly optimistic choice of undersuit, a minor leak and a lot of static drills lead to me jibbering with cold after 70minutes in 8degreesC water. Plus, I've forgotten how to dive, or worse, my body thinks it knows how to dive on open circuit and it is fighting my head which is trying to learn new skills, oh, and I'm hugely overweighted on the first dive and still overweighted and cold on the 2nd dive despite an extra layer of thermals and less lead, nevertheless, we have repeated a whole range of skills & Dennis thinks I've done OK (or he is being polite).
Day 3: The weather continues to be fine and we almost have Capernwray to ourselves, did I mention the vis was awful though? never seen it this bad here. Today was better - change of undersuit and I am toasty warm all day, even with 60minutes+ dives, I am still a bit overweighted, actually this pleases me becaue it means I am not going to need nearly as much lead as I thought and I have an excuse for my buoyancy control still being awful ;-).
We do two dives today, exploring the bottom of the quarry, doing more and more repeat drills, bail outs, dil flushes, repsonding to flash cards from Dennis of High O2, low O2, hypercapnia symptoms, cell errors and so on. We run the unit in manual and get a feel for how much O2 to add and how often to maintain the set point, then do the same again but 'blind' (no looking at handset unless it you get an alarm). I feel like the regular drills are settling in - pre dive: assemble, positive and negative pressure checks, calibrate, pre breathe, buddy check, dive in: bubble check, linearity check, set point change, and so on. DSMB deployement requires some practise, but we don't embarass ourselves too much. We have a practical session on maintenance between dives and a thorough lesson on how to clean the units at the end of the day, in the cafe over bacon butties and hot choclate we are learning the theory of CCR dive planning, additional first aid and the responsibilities of ownership, it is starting to come together.
Day 4: The fine weather is fading (just in time for the Easter break, naturally), more showers than sunshine today. The vis remins awful and the water cold. Today I get my OBV sorted out and give it a run. I've also put the intergrated weights back on the harness and made some final adjustments - I'm now trimmed out and correctly weighted. I feel like my brain has started to integrate the new 'rules' for buoyancy and I feel a lot happier diving and can concentrate on skills and drills - of which there are many. Today we add AAS ascents to the mix, bailing out to off board and onboard gas and we finish off with a full bail out, mid water dsmb deployment and emergency ascent. In the middle of this drill my O2 manual inflate unscrews itself and I have to do an O2 shutdown for real. This actually is no bother so I must have learned somthing! When we suface I still have all the parts in my hand to put it back together, too.
On the walk back to the benches Dennis informs us we have both passed the course, so it is smiles all round :-)
In conclusion: I am really glad I took the leap, it is early days and I still have to get in the sea, but I really like being underwater and being on closed circuit. It really isn't a complicated as some people make out, different yes, but not so much. I was really put through my paces and also enjoyed being a student again - a reminder we are all always learning and of the the concentration and confusion some of my own students must suffer!
Next stop - the sea!