Ballast

Ship

In navigation, the ballast is the whole of the weights which one fastens in the content of the boats, or which belong to the skittle.

They ensure the Stabilité of the ship and/or the depression necessary to obtain a sufficient immersion of the propeller and better nautical qualities. Formerly, the sailing ships were ballasted with sand. The current ships are it with sea water injected into capacities called ballasts with sea water.

A ship is known as on ballast when it does not have a cargo or of loading.

deep-sea Diving

In Plunged underwater, the plungers are often obliged to be ballasted in order to be able to immerse itself correctly. The natural buoyancy of the Human body, associated with the Néoprène of the Combination of diving frequently maintain the individual on the surface. This ballasting will have to be sufficient to be able to hold a stage of decompression with 3 meters of depth without effort.

It is thus necessary to be equipped with a sufficient ballasting, called leads or girdles lead .

Ajusement of ballasting

Ballasting is variable according to many factors: equipment of the plunger (volume and type (short/long material of the block), natural density of this one, Salinity of water, experiment, etc

It can vary from 0 (for a plunger without combination) to 12 or 15 kg.

Choice of ballasting A typical exercise being used to determine ballasting necessary consists, at the end of the diving, to remain on the surface with the empty waistcoat. The level of water must then arrive in the middle of the mask. In order to be adjusted its ballasting, should then, while being done of another plunger, add or withdraw gradually weights to refine its Flottabilité.

Types of ballasting

In order to optimize the weight ratio/volume of ballasting, this one is often carried out in Plomb. These leads are in general small paving stones of 500 G, 1 kg, 1,5 kg or 2 kg.

girdles lead : they are belt from approximately 5 cm broad which is fixed by means of a fast system of dégraffage around the taill. One there places and withdraws leads at will. This type of belt can be equipped with small pockets, like a cartridge pouch, in order to place there leads
bags of shot : more flexible of employment, they slip into the pockets envisaged for this purpose of the Gilet of stabilization. A system of closing in Velcro makes it possible to make them quickly fall
leads from ankle : they set in bracelets around… ankles and make it possible to be maintained vertical. They are used little because tiring with the use at the time of the palmage and thus increasing factor of consumption of Oxygène. The plungers in combination seals use them to keep a plate of the neutral body.
the professional plungers (Diver) use, as for them, of the shoes of ballast heavily leaded in order to be able to work at the bottom of water.
harness of ballasting : mainly used by the tight plunger apneists and lres because of important ballasting need by their practice.

Safety of ballasting

Ballasting is to be considered with precaution in deep-sea diving because it can cause accidents:

at the time of the descent , if ballasting is too important, the plunger will run and will not have time nécessaier inevitably to correctly carry out his Manœuvres of balancing. It risks a accident then barotraumatic.
during the diving :

if ballasting is too important, the plunger will have to provide more effort to be maintained above the bottom and advances, consuming more air (and being likely to miss some at the end of the diving) and risking a breathlessness
if ballasting is not important enough, it can be involved towards surface, being exposed to a Accident of decompression, even with a pulmonary overpressure

at the time of the gone up : in addition to the risks quoted above, increased by the proximity of the surface and a greater variation of Pressure, it can in the event of deficit of ballasting not succeed in holding the stage of decompression and going up on the surface, thus risking a Accident of decompression.

In the event of accident occurring under water, if the fellow-member does not manage to go up his victim, it will lighten it its belt (or of its ballast trim system), in which case, the plunger deus are likely to be trained towards surface without being able to control their speed of increase, in no other case, a ballasting must be withdrawn at the bottom (risk of " increase ballon").

See too

Ballast: English term become synonymous with ballast.

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