How can a submarine control its sinking and floating?

Answer 1

A submarine can descend or rise by changing its overall density relative to the water around it. It does this by filling its ballast tanks either with water (increasing its density) or with air (decreasing its density). Decreasing the amount of water in its ballast tanks by replacing it with air lowers the total mass of the submarine; this decreases its density.

Compressed air from storage is vented into the tanks, pushing the water out the valves underneath. The ballast tanks full of air make the submarine less dense, so it rises.

To descend, the bottom valves allow water to enter the ballast tanks, and the air escapes from valves on top; as the tanks fill with water, the sub again becomes more dense relative to the water around it, so it descends.

Answer 2

If the question refers to the submarine's ability to maintain a certain depth, the answer is probably that the trim and the planes are employed to hold at a given depth. It might help to recall that a submarine is set up to be neutrally buoyant while underwater. By the use of trim to keep the submarine running level in the water with the planes at a zero angle, the planes can themselves be nudged a bit to push the submarine a bit more or less deep in the water.

Answer 3

A submarine moves up and down in two processes. First you must know that submarines are built to be neutrally buoyant, meaning it can sink to whatever level it wants, and also that they have large tanks of compressed air on board for the first process. The first process uses large tanks on the outer part of the submarine. these tanks are called "Bladders" or "Bowels". The submarine captain orders his crew to "vent", or empty, certain bowels. Each one has a number to it so he can tell his crew which ones he wants emptied. Venting releases the air contained in the bowels and helps the submarine dive. When the sub wants to surface, they will close the bowels and fill them up with some of the pressurized air in the tanks. The other process is often used along side the previous one. It involves the use of small "wings" on the sides of the submarine, as well as the submarines forward movement. It works like the control surfaces on a plane. These "wings" are called dive planes. The captain will order his crew to set the dive planes to a certain angle, thereby setting the rate of the dive. The faster the sub is going, the faster it dives. A good example of this is the book/movie "The Hunt For Red October". I Won't spoil the story for you.

Answer 4

well the ballast tank keeps air and water so that makes it float and sink

Answer 5

boating techniques of various types