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LEARNING TO LIVE WITH REBREATHERS
NIGEL EATON, EDITOR
how safe are closed-circuit rebreathers (CCRs) for sport diving? That's the issue explored by Louise Trewavas and Chris Boardman in two special reports in this issue of Diver.
Given the unexpectedly high number of recent deaths among rebreather users, Louise sets out to identify potential problems and investigate how divers feel about the safety of units such as Ambient Pressure's Inspiration.
Incident statistics can, as she points out, be deceptive. But she describes a recent dive during which her rebreather played a nasty trick which left her shaken and perplexed.
Meanwhile, Diver's training correspondent Chris Boardman samples a five-day starter course for the Inspiration and gives his verdict on the unit's suitability for sport diving. It demands a highly disciplined approach, he decides, and is therefore only suitable for a minority of divers.
And he reports the view of the fellow-diver on his course that, in order to maintain familiarity, the device must both represent a diver's primary kit and be used on a frequent basis.
What other factors might be significant? We know that, technically speaking, CCRs are a viable means of breathing under water. (In the case of the Inspiration, there is even CE safety approval in the UK.) But are the training and induction adequate? Is there a case for an automatic refresher course if a diver has not used a CCR for several months or even years?
Are procedures with the unit sufficiently clear and intuitive in normal use? Are such procedures workable when things go wrong because of momentary inattention on the part of the user (bearing in mind that any gas problems may well compromise the user's capacity to deal with them)?
Are procedures sufficiently clear when there is a problem caused by an external factor - a downcurrent, upcurrent, loss of a fin or mask, the user getting caught in nets, or whatever? Also, considering the extended dive times available to CCR users, is the matter of thermal protection being adequately addressed?
Last but not least, should more emphasis on a buddy-type system be encouraged to provide back-up in times of trouble?
As Louise, Chris and many other users acknowledge, the attractions of CCRs for enhancing diving performance and pleasure are immense. These benefits must not be jeopardised because of poorly thought-out training or techniques.
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