Gato Class: Ballast System by Mike Keating
Bow Buoyancy Tank - Being above the waterline, when surfaced. It has
little effect on the Sub's operation. It's only purpose is to give the bow
some added buoyancy when surfacing. This reduces the time it takes to surface
by bringing the bow up faster than would normally be the case. It is the
first tank vented on diving and the first blown on the order to surface.
Safety Tank - Normally, safety tank is kept full of water, and
compensation is computed on this basis. In the event of a submerged
emergency, it can be blown, giving the boat extra buoyancy. It is, in effect, a
margin of safety, hence the name.
Main Ballast Tanks - Just what it says.
Fuel Ballast Tanks - These are nominally ballast tank. But they may be
filled with fuel for extended patrols.
Negative Tank - I'll quote directly from the manual:
"Negative tank,
located inside MBT 2A and 2B, is used to provide negative buoyancy for a
quick dive."
"Negative tank is built to withstand full submergence pressure and can
be used as a variable tank..." It's connected to the trim system.
"The snorkel induction mast is drained to the negative tank (when)
preparing to snorkel." The same amount of water is blown out of negative at
the finish of snorkeling, when the snorkel induction mast refills, with water.
