Download - AP Diving

SECTION 20
20.0
DIVING DEATHS
“Whether divers die using open circuit equipment or rebreathers, they die for the same reason – they are
not aware of or fail to remain within the limitations of their kit!”
The easiest way to explain this is to give you some examples:
a) Many Open Circuit sport divers die because they run out of air, many struggle to the surface and then
find they can’t stay afloat and drown. So what went wrong? Was running out of air the problem or was it
simply their lack of planning/knowledge to deal with the situation from then on. The answer is both of
course, but fundamentally the real problem was lack of awareness in knowing the equipment limitations: the
gas needed to be monitored more closely during the dive and prior planning was necessary to deal with
that scenario should it occur. In this example when s/he got to the surface it would have been a good idea
nd
to drop the weight-belt or inflate the BC from a 2 air source. So, the equipment choice and combination
had to be correct, the diver then had to have the ability to use the appropriate piece of equipment including
the mental strength to use it. The mental strength can be improved relatively easily: practise, practise,
practise.
b) Increasingly, technical Open Circuit divers die through a combination of over-weighting and breathing the
wrong gas either in the shallows or deep.
c) Some leap over the side without turning the tank on, and then don’t have the equipment sorted or due to
nd
lack of practise can’t deploy a 2 mouthpiece.
The above “open-circuit” instances occur a lot, 20 to 30 times per year in the UK alone!
Rebreathers bring with them new opportunities but also new limitations of which the diver must remain
aware.
The following are identifiable reasons why divers die using rebreathers:
1. Over-use of the CO2 absorbent.
2. Improper equipment assembly, followed by inadequate monitoring of system(s).
3. Inappropriate equipment selection or combinations e.g. dry suit inlet valve hose tucked under
counterlungs making it impossible to disconnect in the event of a free-flow. New under-suit
hindering the dry suit exhaust.
4. Failure to switch on the handsets, followed by inadequate monitoring of system.
5. Use of low oxygen percentage diluents and breathing them near the surface either through an open
circuit valve or through the loop but then also failing to ensure the system is turned on & actually
adding oxygen.
6. Ignoring system warnings.
7. Failing to notice lots of bubbles, failing to monitor gas pressures, only having one bail out method:
Open circuit bailout is no use to you if you have no gas in the tank!
This list is not exhaustive but gives an indication of the importance of “Being aware”. Know the equipment
limitations; know how it is supposed to be working, know whether it is working as you expect it to, be aware
of how you feel – you are part of the loop too. Then practise and practise so you can reach all the buckles
and valves and think through the problem scenarios so you are better mentally prepared to deal with issues
as they arise.
Providing you are aware, rebreathers are safer than Open Circuit; they give you much longer to resolve
issues before they become life threatening.
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