HARD RUDDER A rudder angle of about 37 degrees. An emergency order because it risks being unable to return the rudder to an amidships position.
HARDENED SAIL A sail constructed of 3 inch thick HY-80 steel designed to break through polar ice.
HEAVY WATER Deuterium. Used in nuclear fusion reactors or fusion (hydrogen) bombs.
HELM The wheel that turns the ship’s rudder. Also short for helmsman.
HF (HIGH FREQUENCY) Radio waves capable of reception continents away. Reception is often unreliable, susceptible to various atmospheric conditions.
HOMING A torpedo in the final stages of arming and pursuit of a target.
HOT RUN A serious emergency resulting from a torpedo that starts its engine while still in the tube or in the torpedo room. Hazards include the toxic gas exhaust and probability of warhead detonation.
HOT STANDBY A condition of a shutdown reactor and steam plant such that the systems are kept as warm as possible to allow a more rapid startup.
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 1/3 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.
HYDRAULICS Use of oil under pressure to cause motion in large equipment. Used to move the planes and rudder and to raise masts and antennae. In the nuclear plant, primary coolant (water) is used to move valves.
HYDRODYNAMIC FORCES Lift, downforce, or drag caused by the flow of water over the surface of a moving object.
HYDROPHONE A device that converts mechanical motion of soundwaves into electrical signals to be amplified and analyzed by the sonar system. Somewhat like a large microphone. A set of hydrophones forms an array. Hydrophones are passive devices designed for reception only. A transducer can either receive or transmit sonar pulses.
HY-80 STEEL A special alloy of steel made for the Navy. HY stand for high yield. 80 stands for yield stress of 80,000 psi. One of the strongest and toughest steels made. Used for the pressure hull plates and frames of the Piranha and Los Angeles classes.
IMMEDIATE The priority of a radio message just below FLASH. Receipt required within an hour.
IMPLOSION An inward explosion, such as a pressure hull crushed by seawater pressure.
INCLINOMETER A liquid filled tube in the shape of an upside down U with a small bubble at the top. A low-tech method to measure the angle or roll of the ship.
INDUCTION PIPING Piping from the snorkel mast to the ship for use by the diesel generator when the ship is snorkeling.
INTAKE DIFFUSER The air intake of a jet engine. A diffuser is the opposite of a nozzle. It slows down the incoming airstream and raises its pressure.
INTEGRATE The accumulation of data of the BAT-EARS narrowband sonar processors. Tonal frequencies are examined and plotted against time. The longer a tonal is heard, the more certain the computer is that the tonal is not random but is a contact.
INTERLOCK An electrical circuit or mechanical device that prevents unsafe actions. A mechanical example is the shaft that prevents opening a torpedo tube inner door when the outer door is already open, thus preventing opening a hole to the ocean. An electrical example is the reactor protection circuits scramming the reactor if the plant exceeds 103 % power to prevent a meltdown.
INTERMEDIATE RANGE A region of reactor power that is passed through on the approach to the power range. When in creasing power, the reactor is just slightly supercritical. When decreasing power after a scram, the core is subcritical. The region of neutron level between the startup range and the power range.
INVERTER An electrical device that converts DC power into a step AC current. Used to drive control rod motors.
INVERTER ALPHA The inverter normally used for the controlling rod group.
JAM DIVE An emergency that results from either the sternplanes or fairwater planes failing in the dive position, forcing the submarine toward crush depth. A highspeed sternplane jam dive is the classic accident taught at Submarine School in the diving simulators. Immediate actions include reversing the screw to All Back Full and emergency blowing to the surface. Only one in five simulations results in recovery of depth control most students are blasted down to crush depth no matter what they do.
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. When in a tactical situation, the JOOD is a senior qualified officer who shares the fire-control duties with the OOD and is generally responsible for the fire-control solution and release of weapons.
KEEL In the old days of sail, the keel was the plank that the ribs of the ship ere attached to, forming the backbone of the hull. Cylindrical submarine hulls do not have a physical keel. The keel is by definition the lowest point of the hull.
KH-17 Newest generation of Bigbird spy satellites. The KH stand for Keyhole — appropriate for a spy platform.
LAMINAR FLOW Smooth, layerlike, near frictionless flow over an object.
LATCH RODS The order to increase the voltage of the electromagnets on the control rod drive mechanisms to engage the motors to the rods after a scram or shut down.
LATCH VOLTAGE The increased voltage applied to the control rod drive mechanisms in order to latch rods.
LD-50 The radiation dose that will statistically kill 50 % of a population exposed. About 500 rem.
LEFT-TO RIGHT TAG REVERSAL The result of a torpedo in passive search mode doing rudder wiggle. If the target moves left and right, the target is confirmed as valid. Much like a dog cocks its head when it hears prey.
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 fire-control solution. Three legs confirm the solution.
LINE-OF-SIGHT (1) The line from own ship to the target ship. (2) A mode of the fire-control system used in Tape Mode and during a Snapshot. The display shows own ship as a rowboat, the target ship as another rowboat at the end of the line-of sight. The operator matches the target bearing and the bearing rate to get a crude firing solution. (3) A description of the travel of UHF radio waves, which travel in straight lines.
LIQUID METAL COOLANT Use of liquid metal as reactor coolant instead of pressurized water. Sodium and barium are two popular coolants. Abandoned by the U.S. Navy due to the dangers of a sodium-water reaction.
LIST Tilt of a ship to the side.
LITHIUM BROMIDE AIR CONDITIONER One of the air conditioners onboard that uses the absorptive method of heat transfer.
LOCKING IN/LOCKING OUT Entering or leaving a submerged submarine through the escape trunk (airlock).
LOFAR Low frequency analyzer used to determine number of screw blades on a contact’s screw.
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.
LOOKDOWN-SHOOTDOWN RADAR A radar capable of seeing down into the radar grass for the purpose of destroying low flying objects.
LOOP (1) A set of piping in the primary coolant system. (2) The VLF antenna.
LOS ANGELES CLASS The class of submarines built after the last Piranha class. Faster but limited in depth. Hold more weapons and run quieter. Disadvantaged by inability to go under the polar icecap. Also less survivable than the venerated Piranhas due to the reduc
tion of compartments from 5 to 2.
LOSS-OF-COOLANT ACCIDENT Nuclear accident caused by pipe rupture or system failure such that coolant is lost, leading to extreme temperature excursions and probable reactor meltdown. Three Mile Island was a loss-of-coolant accident.
LOW PRESSURE CUTBACK A cutback due to low pressure in the core. A protection against oncoming loss-of-coolant accident or loss-of-pressure accident.
LOW PRESSURE CUTOUT SWITCH A switch that alters reactor scram trip setpoints based on the current operation of the system.
LOW-PRESSURE TURBINE A turbine that accepts low-pressure steam from the high-pressure turbine and extracts energy from the steam for mechanical work.
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.
MAD (MUTUAL ASSURED DESTRUCTION) The theory that a nuclear enemy will be deterred from launch of his nuclear weapons by the knowledge that if he launches, he will be destroyed by America’s nuclear arsenal.
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 COOLANT AVERAGE TEMPERATURE (T-AVE) A rough estimate of in-core temperature found by averaging water inlet temperature and outlet temperature.
MAIN COOLANT CUTOUT VALVE (MCCOV) A large gate valve designed to isolate a coolant loop from the core in case of a fast leak.
MAIN ENGINES (PROPULSION TURBINES) The large turbines that extract energy from steam and convert it to power to turn the screw.
MAIN SEAWATER SYSTEM The seawater piping and pumps that force seawater through the main condensers to condense steam into water for boiler feed.
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 AMR 2 that can isolate the main steam system in the event of a major steam leak.
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.
OXYGEN GENERATOR See Bomb.
PARALLEL Electrical term, meaning connecting two bus AC load centers with a circuit breaker. The loads have to have the same frequency and be at the same point in the sine wave or else equipment can be damaged and fires can start.
PASSIVE SONAR Most common mode of employment of most submarine sonar systems. Sonar system is used only to listen, not to ping out active sonar beams, since pinging gives away a covert submarine’s presence. Use of passive sonar makes it difficult to determine a contact’s range, course, and speed (solution). TMA is the means of obtaining a solution when using passive sonar.
PATROL QUIET Ship systems lineup to ensure maximum quiet while allowing normal creature comforts such as cooking and movie watching. Maintenance on equipment is allowed, if it does not involve banging on the hull. Noisy operations are only permitted with the captain’s permission, such as reactor coolant discharge, steam generator blowdowns, etc.
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