Explain how a submarine can submerge or float itself in the sea?

Question

Explain how a submarine can submerge or float itself in the sea?

Answer 1

Submarine have large tank in the middle of the Submarine, when it needs to sink down it would just open the valve, the tank is normally vacuum and it would take in water to sink.

When it needs to go up this water inside the tank is pumped out using large pumps creating a vacuum which causes it to rise up.

Answer 2

This explanation is for submarines such as what the US Navy has commissioned for its submarine fleet and not for simple submersibles

In order to submerge, the main ballast tanks (those tanks between the outer and inner hulls) are flooded by venting air from the top of the ballast tanks. This neutralizes the bouyancy of the sub, but does not itself submerge the boat. The submarine's control surfaces (stern planes, and fairwater or bow planes) drive the submarine up and down through the water just as the rudder turns the boat. It's 3 dimensional controls like that of an airplane except that the US had a submarine fleet three years before the Wright Brothers went to Kitty Hawk.

The submarine can come up to the surface without blowing ballast tanks by just driving up to the surface. This is enough to expose the full height of the sail and can allow for the maneuvering of the boat to be directed from the flying bridge.

In order to expose the topside of the submarine for mooring the main ballast tanks are blown by a low pressure (high volume) blower.

There are trim tanks in the submarine for controlling the 'bubble' of the boat, and a few other tanks for controlling depth should the boat be running at extremely slow speeds. In this manner water is taken in and dispelled in order to control depth but it is only for tens of feet and not for control of depth over the entire range of the submarine's capabilities.

Answer 3

they have large ballast tanks that can take on water to sink or be filled with air to rise.