How does a submarine stay under water?
Okay for US submarines no-one is really right. For US Submarines we have what are called Main Ballast Tanks (MBT). These tanks have openings on the bottom, always open to the sea, and vents at the top, opened when submerging, we are using the glass under water idea. When we want to submmerge we open the vents at the tops of all the MBT’s at one time. The air escapes through the top, and water fills in from the bottom. These tanks are either complteley wet or dry, not a mix, expect when blowing or flooding. When the tanks fill with water we hope to gain slight negative bouyancy and slip under the water. We attempt to maintain neuteral bouyancy, or at other time very slight positive or negative bouyancy. To do this we have Variable Ballast Tanks. We move water to and from these to achieve our Trim (bouyancy), and control the list of the boat. When we want to surface we usually use Low Pressure Air, from a blower. The vents are shut on the MBT, and the blower pumps LP air into the tanks o
