MANEUVERING The nuclear control room, located in engineroom upper level. Smaller than most closets.
MANEUVERING WATCH The watch stations manned when a ship gets under way in restricted waters.
MARK 37 TORPEDO Torpedoes used in the early nuclear submarine classes. Driven by electrical motors.
MARK 49 TORPEDO (HULLBUSTER) Current version of the torpedo in use by the submarine fleet. Has a range of about 20 to 25 miles, carries a 1500 pound load of shaped charge explosives, and has a top attack speed of 50 knots. Depth limited to 3500 feet.
MARK 50 TORPEDO (HULLCRUSHER) Experimental prototype of the weapon designed to replace the Mark 49, for use against large double hulled deep diving submarines. Maximum depth is 10,000 feet. Shaped charge warhead 100 times more effective at hull rupture than the Mark 49. Maximum speed is 55 knots.
MARK I FIRE-CONTROL SYSTEM Full name is the CCS (Combat Control System) Mark I. The system has three positions, each capable of some two dozen displays for finding target solutions and programming weapons.
MATCH BEARINGS AND SHOOT Captain’s order to shoot a torpedo after resetting the fire-control solution to match the actual bearing and bearing rate of the target. Used with older fire-control systems. (See Shoot on Generated Bearing).
MELEE A condition in which two submarines in combat are aware of each other’s presence. Pirecontrol situations using passive sonar become impossible to ascertain due to constant maneuvers of the target. Both combatants tend to switch to active sonar and get weapons in the water. If the ships are too close, weapon targeting becomes nearly impossible and collisions become highly likely. In some situations, commanding officers may elect to clear datum until the battle can be controlled.
MEGATON Nuclear warhead yield equivalent to a million tons oftnt.
MELTDOWN Gross fuel element failure and melting in nuclear core, usually from overheating. Overheating can be caused by lack of cooling in a loss of coolant accident or by excess reactivity addition as in a control rod jump. Hazardous because highly radioactive products of fission are released to the environment (a typical Navy reactor midway through core life has enough radioactivity to rival the release from Chemobyl). Also dangerous because the melted fuel can collect at the bottom of the reactor vessel and melt through the metal, breaching the hull. Finally, there is a slight chance of the melted fuel mass becoming critical at the bottom of the core, leading to a prompt critical disassembly.
MOTOR GENERATOR One of two large machines located in AMR 2 upper level. It is a motor connected to a generator on the same shaft. The unit can convert DC electrical power to AC power, when the battery is supplying ship’s AC loads, or from AC power to DC power, when the turbine generators are charging the battery.
MIZ (MARGINAL ICE ZONE) An area of drift ice and icebergs in the region between open water and the polar icecap.
NESTOR SECURE VOICE A UHF radiotelephone communications system that encrypts a voice signal prior to transmission and decrypts it after reception. Can be transmitted to the satellite and beamed worldwide. Fast, secure means of communication.
NEUTRON FLUX The amount of free neutrons in a specific volume during a specific time interval. Roughly proportional to reactor power level, i.e., to the fission rate in a core.
NEUTRON LEVEL Number of neutrons per second received at a probe outside the reactor vessel. Directly proportional to reactor power level (fission rate).
NEUTRON RADIATION As a result of uranium fission, each fission yields two to three neutrons. Many of these leak from the core, irradiating neighboring compartments and people. Elaborate shields are constructed, but nothing stops all the neutrons. Also a result of spontaneous fissions in nuclear warheads.
NEWTON A unit of force named after Sir Isaac Newton. Roughly one fifth of a pound.
NLACM (NUCLEAR LAND ATTACK CRUISE MISSILE) A cruise missile capable of attacking a land target using stellar or radar contour navigation. Examples include the Javelin (American weapon, built by Dynacorp International) and the SSN-X-27 (Russian, built by the Severomorsk Weapons Industrial Company Number 427).
NMCC (NATIONAL MILITARY COMMAND CENTER) A nerve center in the Pentagon where, in theory, orders would originate for fighting a nuclear war. Seasoned officers scoff at the idea that NMCC would survive the first ten minutes of a surprise decapitation assault.
NOFORN A level of classification of information that indicates no transmission allowed to foreign nations.
NONVITAL BUS A misnomer for a group of electrical loads supplied off the same turbine generator breaker. While the loads are indeed vital, their loss will not immediately lead to loss of the ship. Examples include sonar and fire-control, fast speed reactor main coolant pumps, and the wardroom video machine.
NOZZLE The opposite of a diffuser. Converts pressure energy of a fluid stream to velocity (kinetic energy).
OIL SHIELD TANK A tank surrounding a reactor compartment used to shield against neutron radiation since oil is an excellent shielding material and needs to be carried aboard for the emergency diesel generator anyway.
ONE THIRD SPEED First speed up from All Stop. Usually gives about 5 knots. Equivalent to the British Dead Slow Ahead.
OOD (OFFICER OF THE DECK) Officer in tactical command of the ship, a sort of acting captain. Directs the motion of the ship, giving rudder, speed, and depth orders. Responsible for ship’s navigation, operation of the ship’s equipment, and employment of the ship’s weapons. Usually has the Deck and the Conn. Needs captain’s permission to do certain operations, such as go to periscope depth, start up the reactor, transmit active sonar or transmit radio, or launch a weapon.
OP Operation or mission.
OPAREA A specific ocean area devoted to a particular exercise or operation. Some OPAREA’s are permanent, some are established only for one exercise.
OPERATING ENVELOPE A region of speed and depth defined for submarine operations. Outside the envelope, the ship could suffer a casualty and sink (the warranty is off). Example: going flank speed at test depth is outside the envelope, because a sternplane jam dive would send the ship below crush depth before she could check the speed and emergency blow to the surface. Operating outside the envelope is done only with captain’s permission.
OPERATIONAL MODE SELECTOR SWITCH A rotary switch on the Reactor Plant Control Panel that determines reactor operational mode, such as shutdown, normal, and cutback override.
OPERATIONS COMPARTMENT Forward compartment containing the control room, torpedo room, crew’s mess, and crew berthing.
OPREP 3 PINNACLE Name of a message that is sent with FLASH priority to the White House and NMCC telling of a dire emergency requiring immediate action, such as an incoming nuclear assault.
OUTBOARD (1) Away from the centerline of the ship, toward the outside of the ship. (2) A small motor with a screw lowered from AMR 2 lower level; the outboard can be trained in any direction to give the ship thrust out from the pier when getting under way.
OUTCHOP Formally leaving one commander’s authority and entering another’s. Also has the meaning of leaving one ocean and entering another.
OVERHEAD Nautical term for ceiling.
OWN SHIP fire-control term for the firing ship.