Wiktionary
n. One of several external or internal tanks fitted in submarines; when filled with seawater they allow the boat to submerge; when emptied using compressed air buoyancy is restored and the vessel rises towards the surface. auxiliary ballast tanks within the pressure hull allow the submarine to be trimmed.
Wikipedia
A ballast tank is a compartment within a boat, ship or other floating structure that holds water, which is used as ballast to provide stability for a vessel. Using water in a tank allows for easier adjustment of weight than stone or iron ballast as was used in older vessels. It also allows for ballast to be pumped out to temporarily reduce the draft of the vessel when required to enter shallower water.
Usage examples of "ballast tank".
The ninth he placed in the center ballast tank amidships, not to blast a hole for the waitÂ.
The ninth he placed in the center ballast tank amidships, not to blast a hole for the wait-ing sea, but to help crack the spine.
Inside it was a water-filled ballast tank, a beehive of cellular baffles seven feet across.
Hunley had miscalculated his angle of descent and allowed the forward ballast tank to overflow.
There's a safety margin built into the Lamprey, so it's prob- ably no big whoop, except for the lame ballast tank.
Two hundred yards off the starboard bow of the LNG tanker, Flett eased back the throttles and switched on the ballast tank pumps.
He also reports that the ballast tank pump system was damaged by the forward blast water and is pouring into the tanks through the exhaust tubes.
Schuster silently nodded as he reached up to flip switches on the ballast tank panels while Mike took the empty neat next to him.
Tolland immediately dove down and swam beneath the sub, running his hand carefully across the Triton's more important ballast tank&mdash.
Their pilot, a severe, sensuous woman in her mid-thirties, prepared the ballast tank pumps and other predive systems.
Pitt turned one of the ballast tank valves, keeping an eye on the pressure gauge, and filled it with just enough air to achieve neutral buoyancy.
They found a friggin' extension ladder in the forward ballast tank.