Journey to the Dark Side

Published in Tech Diver Mag, Issue 19, June 2015


I like sitting at the bar talking nonsense, I’m good at it and it’s where I feel comfortable, once there, the idea of leaving becomes preposterous. Metaphorically, my comfort zone is the same, offering protection and sanctuary from what lurks outside. As nice as it sounds, I know I can’t stay in the bar forever, there is a whole world outside that should be explored. With this in mind, I recently leapt out of my comfort zone and changed everything I knew about diving. I finally made the step in to the silent world by getting certified as a rebreather diver.

For years I have given lots of thought to rebreathers, I have read articles and probably like many others, have heard mixed opinions about their safety. “Rebreathers are just death boxes and their users deserve to die!” That was a quote from a customer I heard recently. OK, agreed it is a little blunt, but it does kind of highlight one school of thinking on rebreathers. I find it interesting to hear the difference in opinions within the dive community on the subject. Some love them, some hate them, and many do not know enough about them to comfortably form an opinion.

What is a rebreather? Well, apart from a very big strain on your bank balance, a rebreather is a unit that recycles exhaled gas by filtering out carbon dioxide and giving the user good gas to breath. The APD Evolution (Evo) which I am now certified to use monitors the gas in “the loop” and will give me the best mix possible based on the depth I am at, within the parameters that I have set it. The Evo is a Closed Circuit Rebreather which means that the gas constantly travels through a circuit without being expelled apart from during ascents.

I remember the first time I saw a rebreather, it was on a dive boat somewhere off the south coast of England. As the divers loaded their gear on to the boat, I noticed the conspicuous yellow boxes and recall having no idea what they were or what they did. Being relatively new to the sport, I did not want to expose my ignorance by asking silly questions. Throughout the trip, I kept a suspicious eye on the strange looking devices and their owners hoping to get some clues. When the rebreather divers were getting out of the water and help was required to stow their units on the boat, I was reluctant to get involved thinking that if I grabbed one in the wrong place it may explode. Back on dry land, I went home and started to research these mystical devices, later feeling something of an authority on the subject as I had been near one once.

The main reasons why I had not tried rebreather diving earlier in my career were cost and availability, I expect these are the biggest constraints for most people. I was initially concerned about the safety aspect so spent quite a bit of time researching rebreather accidents and incidents. Time and time again, I came back to the same theme – user error. Like in open circuit, complacency kills. Writing this, I am reminded of a Mark Powel quote “diving is safe as long as you remember it is dangerous” – very true whether you are talking open or closed circuit.

On the subject of safety, I came to learn that modern units themselves are reliable and most often will do what they are built to do. When divers cut corners due to cost, time, laziness or just plain stupidity then accidents happen. My conclusion was to study the hell out of the subject to become as knowledgeable as I could, get good training, stay focused and tread carefully.

As an avid open circuit tech diver, my interest in rebreather diving is depth. The cost of helium is limiting and aside the startup cost, rebreathers are far more economical when using trimix due to their lack of wasted gas. My initial turn offs were their complexity, required time and effort to get ready for the dive and reliability (I have seen many a frustrated rebreather diver have to remain topside due to some fault or another).

My instructor was a bastard named Steve Tippetts. I don’t think he’ll mind me (affectionately) referring to him as such because I firmly believe that he prides himself on being a hard ass instructor. As I mentioned earlier, I wanted good training and Steves tough regimented way fit the bill perfectly. I had worked with Steve for over a year in Divetech and in that time we became friends. Steve took this as fair game to try his hardest to make me cry during the course and I expected nothing less. An IANTD IT, he has had years of honing his skills and developing a whole host of nasty little tricks which he has a habit of pulling out of the bag at the worst times possible. Of course I am dramatizing, by “tricks” I mean carefully placed training scenarios that made me think about what was going on and how to use what I had available to solve the problem. IANTD say that training is paid for but certification is earned, in my experience I fully concur, there was no plain sailing in this course.


During the training, the hardest thing to come to terms with was buoyancy. Losing the ability to control position in the water with my lungs was a challenge. On open circuit I can hang in the water perfectly with next to no movement from my body whatsoever. My first foray in to closed circuit must have looked like one of those air puppet things that you get outside car dealers. It seemed as though my dive skills that took over a decade to acquire had evaporated in to think air. Time to park the ego and get back to learning some basics.

Having the luxury of being surrounded by some very accomplished rebreather divers, I notice that the style looks different to open circuit. The perfect trim and motionlessness that I had spent years striving to develop is not how it works on a rebreather. Even very skilled closed circuit divers often have to fin gently in a slightly diagonal position in order to maintain their depth.

But that’s the whole thing about new experiences, of course there will be differences. As humbling as it was to go right back to square one, the excitement of learning something new and completely different was more than worth it.

So having completed my basic training and done 30 or so dives, what’s the verdict? I like rebreather diving very much, against closed circuit there are advantages and disadvantages. Trimix is a way off yet but drops to 130 feet or so are comfortable. My current opinion is that a rebreather is a tool and is the best tool for some jobs. For example, the stretch of coastline between our two dive centres is 3 km long, I have now dived it both open and closed circuit. On open circuit I carried five 80cf tanks (twins and three staged) and enough weight to sink them all when empty. On closed circuit, I had my neat little rebreather unit and a 40cf bailout. If nothing else I had a very good nights sleep after the open circuit dive which took an hour longer due to the considerable increase in drag and weight. I’m able to shoot far more lionfish without bubbles to scare them away and I imagine that photographers will note similar benefits. However, I do love the simplicity of open circuit and having a full understanding of how each component of the inside of a regulator works is reassuring.

And now my comfort zone has expanded. To carry on the metaphor, the bar just got a lot bigger, has more people in it but the cost of the drinks has risen somewhat. For me, rebreather diving will not fully replace open circuit. I love the capabilities a rebreather provides and it is a perfect vehicle to take me to the depths I want to go to. However, for light recreational diving, I prefer the simplicity of open circuit. Maybe in the long term, my opinion will change, but for now, my perfect world is big enough for both technologies. As far as plans for the immediate future go, all this talk about bars has got me thirsty, time to have a little toast to the new adventure.

One thought on “Journey to the Dark Side

  1. Excellent article, Drew! As an engineer, it pains me when folks think of machines as either good or evil. They all have a purpose and work best when used for the purpose for which they were designed. Rebreather a are no different. Although I do think rebreather technology would be greatly advanced by a reliable, inexpensive CO2 sensor.

    And I have to agree with the assessment of Mr Steve Tippetts as an instructor (the good part … I guess I didn’t see the bastard part!)


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