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3) “Line-pull” communications
“Line-pulls” is one of the oldest methods used to
communicate between divers and surface. A diver
descends pulling along a line from the boat that
stretches through the water and is always kept gently
taut. To communicate, either end uses a series of one,
two, three or four tugs - agreed upon before the dive
and depending on the dive itself - and in general a
long tug means “I'm about to speak”, and an equal
pull in response means “I'm listening”. It seems
primitive, and it is, but it is still widely used by people
working who only need to communicate occasionally.
4) Audible methods for simple communications
Another form of communication that can
be compared to sign language and Morse
code is the use of so-called "bangers":
basic acoustic signalers that generate
audible noises underwater.
They are usually elastics with a rigid
cylinder affixed to the tanks. Pulling on the
elastic and then releasing it causes noises
against the tank that propagate easily
through the water. These audible acoustic signals can then be organized by the
diving group to create a simplified language. For example: one bang =
everything's ok, 2 bangs = go back to the boat, etc.
Two things are required in order to speak
underwater: a sufficiently large volume of air
in front of the mouth, and the facial mobility
needed to speak as we do on the surface.
This requires a full-face mask, or a half mask
in front of the mouth to which the regulator
is attached. The latter was the first affordable
system offered. This mask was relatively
inconvenient because of the precarious seal and the laces. It was also too small
for good performance. Furthermore, it alters the performance of a
conventional regulator, which is designed to be kept in your mouth and not a
few centimeters away. By wearing a full-face mask, you can communicate
without a transceiver; simply speak inside the mask. The Neptune
OCEAN REEF UNDERWATER COM.Distinctive Specialty Course - rel 1.2 2011/05
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