Ballast (marine)

On board the surface vessels

The ballast is a Lest making it possible to manage the stability and/or the plate of a boat, of a ship. They are most usually several capacities being able to be filled of sea water or emptied with the liking of the needs, it by a circuit of Ballastage and using Pompe (S).

At the time of passage in Dry dock the ballasts can be drained by gravity by unscrewing to it (S) Nable (S).

One also commonly calls ballast with fuel the capacities which contain liquid fuel.

When it is about a simple ballast, one places a dense matter (for example of the stones, or more recently of the pig moulds of Plomb S) in the content of the boats to make them more stable, or to correct a problem of gauge.

On board submarines

The ballasts of a Sous-marin are tanks, outside the resistant hull (known as thick hull), which contain Air or Eau. Their higher opening is closed by actionable slaps remotely called purgings, their opening lower does not have an obturator.

surfaces of It, the purgings are closed and the ballast are full with air (like empty water glass turned over in water). to plunge , the submarine opens its purgings, the ballasts fill entirely of water and thus decrease its buoyancy; its weight increases until balancing the Poussée of Archimedes.

Once in diving , the ballasts being full of water, the purgings are closed again for a safety reason. The submarine balances its weight with the push of Archimedes using cases of adjustment under pressure, called rulers, which it more or less fills of water or compressed air. In the same way it regulates its plate via cases of plate, in order to maintain it null. It is said that it carries out its weighing. Thus, a submerged submarine is, like an airship in the air, in position of balance (though unstable) in water (principle of the Ludion); its buoyancy is null and it moves on the vertical plan while acting on its diving ruders and its propulsion.

to make surface , the submarine injects compressed air in the ballast (purgings being closed) to empty them entirely of their water and to find a positive buoyancy. It is said that it drives out with the ballasts.

Other maritime and naval applications

The principle of the ballast is also used by the Bathyscaphe S. the Brise-glace S also use it in order to make roll the ship, and avoid remaining taken in the ices. The floating docks, the ships carry-barges or the amphibious ships use ballasts to decrease their buoyancy and to thus give access to their load into decked (barges, barges, transported ship) or in erasing (barges of unloading). The landing ships also use them for “plager” (operational stranding).

A consequence of the Ballasting

Ballasting is the action to empty or fill the ballasts with sea water. The ballasts of the ships being one of the vectors of transport of alive species, the current regulation obliges the ships to have a plane management of water of ballast this, in order to avoid unbalancing a ecosystem by the possible transport of invasive species.

External bond

Text of the International Conference on the management of water of ballast of the ships

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