Cressi 30628 Manuel d'utilisation - Page 14

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PRE-DIVE CHECKS:

1 - Check that the low-pressure hose is correctly engaged.

2 - Check that the valve fixing nuts are well tightened.

3 - Make sure the tank is held perfectly in place.

4 - Inflate the BCD and check the efficiency of the pneumatic bladder.

5 - Try out all the functions of the Control Unit several times.

6 - Check the operation of the pressure relief and quick dump valves.

DIVING:

Every dive must begin with a preparatory stop on the surface, during which

you must inflate the BCD. This action facilitates floating and swimming and

makes the preliminary operations safer. Once you are ready, you will need

to deflate fully in order to carry out the descent. During the descent, we

recommend inflating the bladder a little at a time so that your buoyancy is

not excessively negative and your speed does not increase excessively. When

you reach your maximum depth or your first stop, inflate the bladder until a

neutral position is obtained. This position makes swimming very easy. Be very

careful not to overdo it, and ideally keep yourself slightly negative. A deep

inhale or an upward kick with your flippers could be enough to change your

buoyancy from neutral to positive and, if distracted, to put you in an extremely

dangerous situation. It could even trigger a very risky and rapid uncontrolled

ascent. To avoid this situation, you need to be able to quickly recognise such a

buoyancy change and to immediately deflate the BCD using the valves. Once

your run time is up, you must ascend, taking care to release the air on a partial

basis, proportional to your ascent altitude. For every diver, ASCENDING must

be inextricably linked to DEFLATING the BCD (and the dry suit). The deflation

must be adjusted to ensure that it is never affected by the positive thrust that

the BCD gives to your body. Once on the surface, reinflate the BCD.

As previously mentioned in the "Control Unit" paragraph, inflation manoeuvres

are carried out using the By-Pass button or by mouth using the mouthpiece

and button. We recommend practising both methods extensively, even if the

first proves quicker and easier. The position of the diver is not relevant to the

effects of the manoeuvre. Deflation manoeuvres are carried out by way of

the control unit, either by pulling it downwards or by lifting the end towards

the surface and pressing the appropriate button, and by way of the quick

dump valves located in the rear part, by pulling the appropriate knobs. During

deflation operations, the position of the diver is very relevant to the effects of

the manoeuvre. They must be vertical with respect to the surface to deflate

using the control unit or the upper rear valve, while they must have their head

down and more precisely the lower part of the BCD upwards to deflate using

the lower rear valve. When deflating, care must be taken to close the relevant

elements as soon as the air has finished flowing out. Otherwise, the water will

begin to enter the bladder, as it is no longer blocked by the air, altering the

buoyancy capacity.

i WARNING!

In BCD models with a rear bladder, when on the surface,

the air mass tends to position the diver horizontally upside down, and the

head may remain submerged in case of loss of consciousness. Their use

is therefore intended for expert divers with an in-depth understanding

of their features.

u WARNINGS:

As mentioned in the previous paragraph, incorrect control of the BCD

can lead to very dangerous, rapid and uncontrolled ascents, which are

almost always responsible for serious or fatal decompression accidents.

In order to prevent these situations, we always recommend gradually

deflating the BCD during ascents to maintain a slightly negative

buoyancy. If you are in a vertical position, this operation must be carried

out using the upper valves; more unusually, if your body is positioned

upside down, you must use the lower valve. As a general rule, you

should always use the valve closest to the surface to deflate.