Quite a bit has been written concerning various techniques
and methods of searching in an underwater environment. There are a
myriad of search patterns that can be utilized depending on such
factors as terrain, visibility, depth, the nature of the object
being sought, etc. However very little has been written concerning
the swimming technique that a diver should utilize when conducting
an underwater search.
This is not a critical concern in clear open water where
limited visibility is not a factor. In such cases a normal fining
technique such as a flutter kick, or even a scissor kick, can be
effectively utilized. However in those environments prone to
silting, normal fining and swimming position will undoubtedly stir
up silt effectively reducing what visibility may be naturally
present in the water to a black water situation.
In potential silting environments it is important for the
stay off the bottom.
Buoyancy control in this regard is critical. Over weighting is the
biggest factor in buoyancy control. Ideally, a diver should wear
only enough weight to remain neutral in 15-20 feet of water with an
empty B/C and a near-empty cylinder (500 PSI).
Part of the solution lies in proper weighting. Excessive
weight worn by a diver causes several problems:
weighting causes a diver to swim through the water at a very
inefficient attitude. The weight belt pulls the diver’s lower
body down while the air in the B/C, in order to counteract the
weight, pulls the shoulders up. This exposes an excess of frontal
surface of the diver and increases drag. Such an attitude makes
for a very tedious search with the diver constantly fighting
against the forces of gravity and buoyancy. Matters become even
more complicated when the area to be searched consists of an
embankment where buoyancy is constantly changing as the diver
moves (in a circular fashion) throughout the search area. For
this reason the “Jack-Stay” should be considered for employment in
the search of an underwater embankment.
air consumption from the added bulk and drag of an over- inflated
B/C. If the B/C is not inflated to compensate for the extra
weight, the diver’s buoyancy is significantly negative causing
constant kicking to maintain position and counteract gravity, thus
increased air consumption.
quicker from working harder than necessary due to the combined
effects of carrying extra weight and fighting excess drag.
Fatigue results in increased air consumption, decreased bottom
time, and decreased size of the search area covered.
breathing rate and nitrogen level causing potential decompression
problems. Increased work causes increased and deeper breathing
resulting in a greater absorption of nitrogen.
In order to stay clear of the bottom, it is necessary to
positive buoyancy. In order to stay in position, it is then
necessary to dive in a head-down/feet-up position utilizing the
fins to counteract this increased buoyancy. This is, needless to
say, not the most efficient of swimming positions, but it is
necessary to get the job done. Weight worn on the waist requires
that the diver arch his back. This places tremendous strain on the
back muscles, especially if a diver is over-weighed. Not only
should the correct amount of weight be utilized, but it should also
be efficiently trimmed. Removing some of the ballast weight from
the weight belt and placing it at the level of approximately from
the shoulders to the bottom of the rib cage will help to naturally
achieve this in-water position.
Fining technique is the other part of the equation. A
full-on flutter kick produces excessive turbulence toward the bottom
and will in short order reduce visibility in a silt prone
environment from inches, or even feet to zero. To avoid this
problem it is suggested that an alternative fining method be
Modified Flutter Kick – this is accomplished by bending the knees
slightly and shortening the kick stroke. When maintaining a
head-down / feet-up position, all fin movement takes place above the
center of the diver’s body thereby minimizing the movement of water
below the diver.
Frog Kick – this
is accomplished by spreading the legs laterally, rotating the bottom
of the fins inward, and bringing the fins together. The frog kick
restricts the thrust and turbulence in the water to the area to the
immediate rear of the diver.
involves a gentle, steady back and forth fin movement with the fins
angled slightly. The ankles are utilized to move the fins in a kind
of oval pattern. Absent any current, sculling allows the diver to
hold and maintain a stationary mid-water position.
When properly weighted and trimmed and neutrally buoyant, a
diver should ideally be able to adjust / control buoyancy through
such subtle means as breathing control or through movement of the
head by use of the planning surface of the facemask.
There are additionally other factors that contribute to
diver efficiency in the water:
Speed of swimming
– The effort required to increase swimming speed is disproportionate
to the result achieved. Doubling the swimming speed of a diver
takes four times the output of energy. As discussed above, as
increased energy is utilized (work is increased) so also is
increased air utilized. The movements of a SAR diver underwater
should be slow and methodical. Slow, short fin strokes are more
efficient than rapid or wide strokes.
(trim) of equipment – Consoles, octopus regulators, lights, etc.
left hanging loosely from a diver contribute to drag as well as
subject the diver to possible entanglement. All equipment should be
secured by snaps, etc. or stored in pockets or pouches to make the
diver and gear as streamlined as possible.
Proper breathing –
Breathing affects underwater efficiency from both an air consumption
and a buoyancy aspect. Breathing should be slow, and deep. Full,
slow inhalations followed by a pause, and full, slow exhalations
will make the most efficient use of the air supply, deliver the best
supply of oxygen to the lungs, as well as off-gas carbon dioxide.
Physical fitness –
Few SAR divers are employed in the diving industry (diving instructors,
commercial divers, etc.) and it is difficult with all of the other
demands of life (work, family, finances, etc.) to do enough diving
to remain physically fit and capable for
SAR operations. Obviously the best exercise to keep in shape for diving is
diving itself. However, other aerobic and resistance training is of
benefit: swimming, running, weight lifting, racquet ball, hiking,
etc. etc. all contribute to an overall level of fitness which will
serve to improve diving efficiency.
Mental attitude –
A diver whose “head is not in the game”, who is preoccupied by work,
family, financial, etc. problems or a diver who is stressed by or
apprehensive about the nature of an operation or assignment or is
worried about some equipment problem or mal-function, will operate