IN THE MIX
PHOTO : CATHY DE LARA
“ In the vast majority of rebreather fatality cases , drowning is the actual cause of death .”
Additional benefits of using an MRS
Many rebreather divers report facial muscular strain and discomfort caused by the positive buoyancy of the breathing loop and / or weight of a BOV . The use of a MRS improves rebreather diving comfort by reducing jaw fatigue , particularly during extended dives using a BOV or when in high water flow environment such as using a scooter .
Change of culture
During the planning , preparation and execution of a dive , we implement the necessary action we feel is required to avoid losing consciousness in the first place . As a result , the “ it will never happen to me ” perception is common . However , such a position was very likely shared by every rebreather diver who has lost consciousness and drowned , many of whom were highly competent and capable divers .
The use of motor vehicle seat belts was strenuously resisted by the automotive manufacturing industry and the general public when first proposed . However , the adoption of seat-belts has significantly reduced motor vehicle fatalities . As a consequence , there has been a change in safety culture and today , few people drive without wearing a seat-belt because the potential life-saving benefits are selfevident . With hindsight , it now seems ridiculous that people were once prepared to accept the likelihood of being propelled at
36 high velocity face first through a windscreen .
With more than a quarter of a century of sport rebreather use now behind us , from the significant body of evidence acquired over this period , it is increasingly clear that rebreather divers are not dying from hypoxia , hypercapnia , hyperoxia , equipment failure or human error ; these are disabling injuries and incident triggers . In the vast majority of rebreather fatality cases , drowning is the actual cause of death . The author therefore believes a similar change of safety culture is overdue within the sport diving community ( divers , instructors , training agencies , international standards authorities , manufacturers ), which if implemented , would likely result in reducing rebreather fatalities .
Going back , then , to the near fatal accident discussed at the beginning of this article , how did the diver make it back home to his family that day ? Leading up to the LoC event itself , the diver ran out of oxygen and failed to pay attention to his displays and alarms once at the surface .
As a consequence , he became hypoxic , lost consciousness and sank . However , fortunately he was in a sufficient depth of water where increasing ambient pressure during his unconscious descent resulted in elevating the breathing gas PO2 sufficiently for consciousness to be regained . Throughout the period of unconsciousness , an MRS preserved his airway , prevented water aspiration and further loss of buoyancy . Although a rare tale of survival , it represents a real-world example of the life-saving potential a correctly worn MRS offers .
The author is a former maritime special operations military diving Instructor and Diving Supervisor , BSAC FCD and CCR AMG IT . As a specialist defence diving consultant , he remains at the forefront of military rebreather development , design , test and training for JFD , the world ’ s largest manufacturer of professional diving equipment .
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