If
you had asked me eight or nine years ago to venture
inside a submerged cavern or shipwreck I would have
thought you where crazy. However, nowadays you'd get
a completely answer: "Where and when do we leave?"
After logging a lot of dives and taking plenty of courses
I now feel comfortable entering these types of environment.
Having said that, this style of diving is not for your
average recreational diver. The dives take a lot of
preparation and planning in order to ensure personal
safety. Participants need to work on their skills and
maintain regular proficiency in their application, since
there is little or no room, for error once you are inside
these confined, and more than likely, dark spaces.
Once inside a wreck or cave, the risk factors jump dramatically;
loss of visibility is a common factor, either from bubbles
breaking up ceiling silt or from being disturbed by
fin action. I have been a mere three metres inside wrecks
and when I looked back the visibility had been cut down
by half.
An important skill taught in cavern and technical wreck
diving courses is utilising different styles of fin
kicks to minimize the disturbance of any silt.
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ACCIDENT
ANALYSIS
Cave and wreck divers have developed an acronym for accident
analysis and contingency planning, T. G. A. D. L. One
interpretation would be "Thank God All Divers Live"
however its real meaning is to describe important traits
of good wreck diving practices.
Thank
= TRAINING
God = Guidelines
All = Air or Gas supply
Divers = Depth limits
Live = Lights
Training
and Experience
About 95% of fatalities in cave systems come from divers
with out proper training and 73% of accidents during wreck
diving occurred when divers enter wrecks without the aid
of a guideline. For fatalities that occurred outside the
wreck, 43% were attributed to 'out of gas situations'.
Guide
lines
In an overhead environments, the lack of a guideline is
the single greatest cause for fatalities; any time you
enter a wreck or cave a guideline should be considered
as your extra 'buddy'. Training in the use of these, and
reels are both key elements of cave and wreck diver training.
Air or Gas Supply
This is much more than 'just watching a pressure gauge'.
In technical, cave and wreck diving, we typically operate
under the 'Rule of Thirds'. This means the diver uses
1/3 of their gas on the outward stage of the dive, 1/3
for the return journey leaving, 1/3 in reserve. Many people
think this may be to conservative but in my opinion, and
I'm sure many others its better to be safe than sorry.
Depth, combined with inexperience and/or poor planning
can also be very unforgiving. Most divers know that gas
depletes more rapidly at depth. Imagine how fast it goes
in a stressful situation such as an entanglement inside
a wreck! Narcosis could also be an increasing factor in
situations where incorrect gas mixtures are used. Oxygen
toxicity is a possibility on improperly planned dives
that fail to take into account the extra workload involved
in a penetration dive.
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Lights
Be prepared for low visibility and loss of ambient light.
For non-penetration dives, a single light source may be
sufficient, but for actual penetration the diver must
carry a minimum of two extra backup lights. But it doesn't
end there, there are specific rules for brightness, burn
duration and configuration that also need to be considered,
and should be included in any training course.
Thailand has lots of wrecks and freshwater cave systems
worth exploring.
Be
smart and get proper training then build up your experience
slowly. Remember, training alone only provides you the
tools. Experience requires repetition and a slow process
of increasing the limits of your diving abilities.
Bruce
Konefe I.T.#47 ANDI
andibk@loxinfo.co.th
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