Fix — A ship’s position. Determined by visual triangulation or radar when close to land on the surface, or by NAV SAT or BE sonar when at sea.
Flag Plot — A chart room used by flag officers (admirals) to plot strategy or determine the distribution of forces.
Flank Speed — Maximum speed of a U.S. submarine.
Requires fast speed reactor main coolant pumps and running at 100 % reactor power.
FLASH — The highest priority of a radio message. Receipt required within minutes or seconds.
Forced Circulation — Forced flow of water coolant through a reactor using pumps, as opposed to natural circulation.
G — A measure of acceleration. The acceleration due to gravity is one g. Two g’s is twice,
Geographic Plot — (1) A manual plot saved from World War II submarine days using the plot table to deduce a firecontrol solution. Works well on unsuspecting targets. Target zigs cause confusion on this plot. Useless in a melee situation. (2) A mode of display of the Mark I firecontrol system showing a God’s eye view of the sea with own ship at the center and the other contacts and their solutions surrounding it.
GMT (Greenwich Mean Time) — A worldwide time standard using the time at longitude zero at Greenwich, England. Also called Zulu time.
GPS (Global Positioning System) — A series of satellites and shipborne receivers enabling extremely precise navigation fixes. Also called the
NAV SAT
Gyro/ Gyroscope — Electrical compass using a rapidly spinning gyroscope.
Head — Seagoing term for bathroom.
Helm — The wheel that turns the ship’s rudder. Also short for helmsman.
Hovering System — A depth control system managed by a computer that keeps the ship in one point underwater. Used by boomers when launching missiles.
Used by fast attack submarines to establish a desired vertical speed (depth rate) to vertical surface through polar ice.
Hull Array — One of the sonar hydrophone element assemblies (arrays) of the BAT EARS sonar suite, consisting of multiple hydrophones placed against the skin of the hull over about one-third of the ship’s length. Used mostly as a backup to the spherical array because the hull array’s sensitivity is reduced by own ship noise inside the hull.
HUMINT — Human intelligence, that gained from foreign agents or American intelligence officers.
IR — Infrared.
JOOD — Junior Officer of the Deck; Assistant to the OOD. When in transit, the JOOD is usually an unqualified officer in a training position, given the Conn and supervised by the OOD.
KH-17—Newest generation of Bigbird spy satellites. The KH stands for Keyhole — appropriate for a spy platform.
LAMPS — Light airborne multipurpose system. Cute acronym for a Seahawk ASW helicopter carried aboard a U.S. Navy surface ship.
Leg — The straight line travel of a submarine doing passive sonar Target Motion Analysis (TMA) between maneuvers. During a leg the crew attempts to establish a steady bearing rate to the target and establish speed across the line-of-sight to the target. Two legs determine a firecontrol solution. Three legs confirm the solution. Four legs indicate the captain is afraid to shoot. A large sign at Prospective Commanding Officer School in Groton, Connecticut, reads “you don’t need another GODDAMNED LEG!”
List — Tilt of a ship to the side.
Locking In/ Locking Out — Entering or leaving a submerged submarine through the escape trunk (airlock).
Lookaround — (1) A periscope observation. (2) A warning by the OOD or captain to the ship control team that the periscope is about to be raised. The Diving Officer and helmsman report ship’s speed and depth as a reminder, since high speeds can rip the periscope off and flood the ship through the periscope hole.
MAD (Magnetic Anomaly Detector) — A detector flown on an aircraft that measures changes in the earth’s magnetic field that could be caused by the iron hull of a submarine.
Main Ballast Tank — Tank that is used solely to hold seawater ballast, weight that allows a ship to sink, or, when blown, allows a ship to be light enough to surface.
Main Engines (Propulsion Turbines) — The large turbines that extract energy from steam and convert it to power to turn the screw.
Main Steam Valves One and Two (MS-1, MS-2)-Large gate valves on the port and starboard main steam headers, at the forward bulkhead of the aft compartment. These can isolate the main steam system in the event of a major steam leak.
Maneuvering — The nuclear control room, located in the aft compartment upper level. Smaller than most closets.
Maneuvering Watch — The watch stations manned when a ship gets underway in restricted waters.
Mark 36 or 38—A torpedo-sized decoy vehicle that transmits the sounds of a submarine and can be programmed to maneuver through the ocean like a submarine; used to evade a trailing hostile ship or torpedo.
Mark 50—Latest breed of torpedo. Also called the “Hullcrusher.”
Mark 80 SLAAM — Submarine-launched anti-air missile.
