IT’S THE ELEPHANT IN THE ROOM, the Banquo’s ghost at every diving party. Just how safe are rebreathers If you’re doing this type of diving, then it is inevitably a question you’ll ask yourself at some point.
And if you’re the right type of diver, you’ll go off and do a bit of research to find the answer. Or “an” answer, as there seems to be a lot of information out there about this subject.
What is universally accepted amid all the conjecture and tall tales is that rebreather diving has a higher level of mortality than standard open-circuit diving.
This was particularly apparent in the early days of rebreather diving outside the military and commercial sphere.
I have my own theories about this, relating to the type of diving that was being conducted – these were exploratory, expedition-style projects that pushed the limits of established protocols and knowledge.
It seems inevitable that when the entire party is tip-toeing along the edge, occasionally one of the group will be lost to the void beside them.

EVERY ONE OF THESE INCIDENTS was a tragedy, but this was genuinely pioneering stuff, and it is fascinating to hear these original divers calmly state that this was almost seen as part of the price for pushing the limits.
Nowadays, a lot more of us own a lot more rebreathers. It’s turned into slightly more of a numbers game as, with statistically a great deal more people involved, inevitably there’ll be more incidents. It’s the nature of the incidents that makes really interesting reading, and it’s this on which the safety protocol of our present set of projects is heavily based.
There is a simple truth at the heart of all this. If you treat this type of diving casually, if you abuse your kit, if you don’t service equipment, or if you ignore certain basic rules, then a rebreather will bite you on the bum. It’s not if, it’s when.
The development of the Hollis Explorer and the Poseidon Discovery – both game-changers in terms of recreational rebreather technology – has removed human error from the equation by fully automating the set-up and check process.
For more-technical rebreathers, however, there is a level of fastidious care and attention required that I must say has been somewhat lacking in my diving career to date.
This is my responsibility to address, a fact borne out by the statistics. A staggeringly large number of rebreather deaths have occurred due to fundamental errors in the pre-dive processes.
Further deaths – but not by a long chalk as many as you might think – have occurred because of equipment failure, and had no relation to the skills of the diver in question.
Other deaths have been nothing to do with the rebreather at all; those standard, tragic incidents that occasionally crop up in the diving world.
It just so happened that the diver in question was wearing a rebreather at the time.

AND THEN THERE ARE THOSE other incidents, the ones that haunt the subconscious. These are the very few deaths where there is no explanation at all, where the diver (and occasionally these have been real icons of the sport) has mysteriously died and there has never been a satisfactory explanation.
It is these that seem to trouble the industry the most, and these that everyone wants to eliminate from the future of the sport.
It’s been a long road bringing rebreathers into the wider diving market, and there have been many – too many – lost along the way.
And so a second question rears its head – here we are in 2013, so with all the lessons learned and the knowledge gained, how do I dive safely when using one
I have had the great good fortune to be working with Kev Gurr and Rich Stevenson, both of whom have developed rock-solid rules for this type of diving.
They are the principles by which we live our diving lives on this present series of expeditions, and – I hope – will be the way I use a rebreather for the rest of my diving days:

1. Every diver, on every dive, runs through a full pre-dive checklist, and performs a full five minute pre-breathe on the unit.
2. No dive ever exceeds the scrubber duration of the unit. Whenever possible, a new scrubber is used on each dive.
3. No diver ever ascends alone, or is left in the water alone.
4. Every gas used by every individual has been analysed by that diver, and logged in a central log. Every cylinder is marked accordingly.
5. It is every diver’s responsibility to check PO2 levels on a secondary handset at least every five minutes during the course of the dive.
6. Every diver has enough bail-out gas to get him either to the surface or to a safe location (such as the base of a shotline where extra gas has been cached).
7. No diver, or piece of equipment, enters the water without the permission of the dive supervisor. In this case Kev. Or “Dad” as we call him, due to his habit of rewarding good diving practice with a gift of a Werthers Original mint and a pat on the head.

There are risks with rebreather diving, but to drift silently through the arch at Elphinstone, or to hang like a ghost in the midst of the great cathedral of the Blue Hole, are moments that make it all very much worthwhile.
I suppose the best you can do is to reach a kind of internal mental pact, an agreement with yourself that after all is said and done, you’ve covered every base possible.