Voyage of the Devilfish

GLOSSARY

ACCELEROMETER An instrument that measures acceleration ing’s.

ACQUISITION A torpedo being convinced that the signals from its sonar gear, active or passive, indicated a confirmed target.

ACR (ANTI–CIRCULAR RUN) A torpedo interlock that prevents the torpedo from acquiring on the firing ship. When the torpedo turns more than 160 degrees from the approach course to the target, the onboard gyro sends a signal to the central processor to shut down the unit. It then sinks.

ACTIVE SONAR The determination of a contact’s bearing and range by pinging a sound pulse into the ocean and listening for the reflection of the ping from the target. The time interval between transmission and reception gives target range using the speed of sound in water. The direction of the return pulse indicates the target bearing. Generally not used by submarines since it gives away the ship’s position. Used by some Russian units for a confirming range check immediately prior to shooting a torpedo.

AFT GROUP The main ballast tanks aft — four are aft of the engineroom, and four surround AMR 2. During an emergency blow, all six of these ballast tanks are blown dry simultaneously.

AKULA One of the newest classes of Russian attack submarines. Similar in appearance to a VICTOR III with the bulbous bow and stem pod on the rudder. Believed to be as quiet as an American Piranha class.

ALFA One of the recent Russian submarine classes. Very small and, until the appearance of the OMEGA class, the fastest nuclear submarine in the world. Also one of the loudest. Manned by a tiny crew of officers, the ship is totally automated. ALFA Unit One apparently suffered a massive reactor accident in the late 70s.

ALPHA RADIATION A positively charged panicle emitted by heavy elements undergoing radioactive decay. Essentially a helium nucleus.

AMINES Chemicals used in C02 scrubber, a bed of amines over which air is blown. Eliminates carbon dioxide, a byproduct of human respiration.

AMP-HOUR A unit of electrical energy that measures the capacity of a battery.

AMP-HOUR METER Digital indicator on the Electric Plant Control Panel that measures the discharge of the ship’s battery in amp-hours.

AMR 1 (AUXILIARY MACHINERY ROOM l) (Piranha class) A mechanical equipment room in operations compartment lower level aft of the torpedo room. Contains the bomb (oxygen generator), forward auxiliary seawater pumps, air compressors, and other ship systems.

AMR 2 (AUXILIARY MACHINERY ROOM l) (Piranha class) A two-deck-high compartment aft of the reactor compartment. Only two decks since it is surrounded by ballast tanks. The upper deck contains electrical switchgear and the reactor control cabinets. The lower deck is home to the main feed pumps, reactor auxiliary systems, and the second bomb.

ANALOG As opposed to digital — an analog instrument has a gage face and a pointer. An analog signal is smooth and continuous, while a digital signal is either on or off.

ANECHOIC COATING A thick foam coating attached to the outside of the hulls of Russian submarines. It absorbs incoming active sonar pulses without reflecting them back while damping out internal noises before they can get outside the ship. Analogous to stealth radar absorptive material on a stealth aircraft. Not used on American submarines since it is bulky and easily torn, and American ships are internally quieter.

ANGLE ON THE BOW The angle between an observer’s line of-sight to a target ship and the target’s heading. A ship coming dead on has an angle on the bow of zero degrees. If the contact is going on a course at a right angle to his bearing from the observer, the angle on the bow is port (or starboard) 90 degrees.

ARRAY A collection of sonar hydrophones or transducers that work together to track a contact.

ASH (ANTI-SELF HOMING) A torpedo interlock that measures the distance from the firing ship. If the torpedo comes back toward the firing ship, at 80 % of the return trip, the ASH interlock will shut down the unit, and it floods and sinks.

ASROC Antisubmarine rocket. A depth charge in the nosecone of a solid rocket fueled missile carried by ASW surface ships. The missile puts the depth charge in the water miles away from the firing ship, allowing the depth charge to be a nuclear warhead.

ASW (1) Antisubmarine warfare. (2) Auxiliary seawater system.

AUTHENTICATOR A packet containing a computer written group of letters and numbers. Packets are under two-man control at all times from production to destruction, and are locked in double safes. No one man has both safe combinations. Used by Russian and American forces to validate or authenticate orders to use nuclear weapons so that a single madman would be unable to launch nuclear weaponry. Destruction is done by first shredding, then burning under two man control.

AUX 2 (Piranha class) A depth control tank (variable ballast tank) beneath the torpedo room.

BEND HYDRAULIC MOTOR (ROTARY PISTON MOTOR) An external engine used in some designs of torpedoes. Hot gases enter from a combustion chamber under high pressure. The gases are expanded in a rotary mechanism of pistons connected to a canted swash plate, convening the thermal energy to mechanical work.

BAFFLES A “cone of silence” astern of most submarines where sonar reception is hindered by engines, turbines, screws, and other mechanical equipment located in the aft end of a submarine.

BALL VALVE A total shutoff valve using a ball inserted in a pipe. The ball has a hole in it to allow flow when aligned with the pipe. When rotated 90 degrees, the flow is stopped by the ball.

BALLAST Weight added to a ship to allow it to submerge, to counter buoyancy. Done by flooding tanks, main ballast tanks or variable ballast tanks.

BALLAST CONTROL PANEL Control panel in the port forward corner of an American submarine’s control room. The console controls the ballast tank vent and blowing system, the hovering system, and the trim system. Also home to the chicken switches, the levers controlling the emergency blow system. Panel is manned by the COW, the Chief of the Watch.

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.

BALLISTIC MISSILE SUBMARINE Nuclear submarine that carries intercontinental ballistic nuclear missiles (SLBM’s— submarine launched ballistic missile). Mission consists entirely of hiding from all other ships and staying in passive radio communication with Washington in the event the President orders a nuclear assault on a foreign country. As opposed to fast attack submarines that do not carry SLBM’s.

BALLISTIC TRAJECTORY Path of an unguided flying object, in a free-fall path determined by gravity, initial velocity, magnetic, Coreolis, and aerodynamic forces.

BARE STEERAGEWAY Minimum speed to allow the rudder and planes to work. About two knots.

BATTLESHORT A condition in which the nuclear reactor’s safety interlocks are removed. Used only in a severe emergency or in battle, when an accidental reactor shutdown is more dangerous to the ship due to loss of propulsion than the potential risk of a reactor meltdown. Only the captain can order Battleshort.

BATTLESHORT SWITCH Rotary switch on a cabinet in AMR 2 upper level that removes reactor safety interlocks.

BAT-EARS SONAR Slang name for the AN/BQQ-7 sonar suite, including the spherical broadband array, the hull broadband array, and the towed narrowband array. Also known as the “Q7.”

BEAM (1) To the side of the ship. (2) An active sonar cone stretching out into the ocean like the beam of a flashlight. (3) A passive sonar reception cone — noise outside the cone will not be received.

BEARING Direction to a contact, expressed in degrees. A contact to the north is at a bearing of 000. A contact to the east is at 090, etc.

BEARING AMBIGUITY When a target is detected on the towed array, its noise could be coming from one of two directions. The ambiguity must be resolved by turning the ship and seeing which new two directions the tonal seems to be coming from, or correlating a narrowband towed array bearing to a broadband bearing. Broadband bearings are never ambiguous.

BEARING DOT STACK A method of finding a fire-control solution on the Mark I fire-control system. The operator “stacks dots” using a knob. The display is a graph of the difference between actual target bearing and solution generated target bearing versus time. When the dot stack is in a vertical line, the difference between where a target is and where he should be is zero, indicating a firing solution. If a target zigs, the dots diverge off either left or right, indicating the target is no longer where the computer’s solution says he should be.

BEARING DRIFT The direction of change of a contact’s bearing, i.e., bearing drift is right when the contact moves from 090 to 095.

BEARING RATE The speed (or rate of change) of a contact’s bearing. A contact that has a bearing change from 090 to 095 in one minute has a bearing rate of 5 degrees per minute right.

BIGMOUTH ANTENNA Slang name for the AN/BRA-34 multifrequency antenna. A radio antenna suitable for transmission or reception of several frequencies including HF, VHP, and UHF. Shaped like a telephone pole, it protrudes from the sail about 25 feet.

BILGES The space at the very bottom of the cylindrical hull of a submarine below the lower level deck. In the engineering spaces, the bilges capture leakage from piping systems for pumpout by the drain system. The bilges also capture any water from flooding so that it can be pumped out before it rises above the lower level deck to damage equipment.

BIOLOGICS Ocean noises generated by marine life forms: shrimp, whales, and other fish and mammals fill the sea with clicks, groans, grunts, and even tonals. The sounds can sometimes be mistaken for F’lbmarine sounds. A current theory holds that submarines transiting at low speeds can attract marine animals, thus shrouding the submarine in a cloak of biologies. For this reason, biologies are usually investigated with narrowband sonar to prove they do not hide an enemy submarine.

BLOCKS-OF-WOOD SONAR Code name for a Russian active sonar that sounds like two wood blocks clicking together. Used almost exclusively by Russian submarines to verify a target’s range immediately prior to weapon launch. Immediate action for an American submarine hearing Blocks of Wood sonar is to call a Snapshot.

SLOWDOWN Opening a valve in a pipe from a steam generator (boiler) to the sea to blow out sediment and boiler chemicals. High pressure of the boiler forces the water out to lower pressure of the sea when at fairly shallow depths. Usually done only at periscope depth. Extremely noisy operation that destroys sonar reception completely.

BLOWING SANITARY Application of high pressure air to a sanitary (sewage) tank to force the sewage out of the tank into the sea. The air trapped in the tank must be vented to the inside of the ship to avoid telltale bubbles that could allow the ship to be detected. The venting makes the ship stink.

BLUEOUT Reverberations and noise from the bubbles caused by an underwater nuclear explosion. Masks sonar reception for hours, sometimes days.

BOMB GRADE URANIUM U-235, capable of fissioning and causing nuclear energy release. High concentrations of U235 are used only in nuclear bombs and in high power-density naval reactors.

BOMB (OXYGEN GENERATOR) An electrical device that puts an ultrahigh voltage on distilled water, causing electrolysis, the breakdown of water into hydrogen and oxygen. The oxygen is put into the oxygen banks and bled into the ship for breathing. The hydrogen is discarded overboard through the auxiliary seawater system. The device, making the explosive combination of oxygen and hydrogen, has the potential to explode violently enough to breach the hull and sink the ship. Affectionately nicknamed the Bomb.

BOOMER Nickname for an FBM, fleet ballistic missile submarine. When used by SSN (fast attack submarine) sailors, it can be a derogatory term. A badge of honor to boomer sailors who see themselves as the lone defenders of America.

BOTTOM CONTOUR NAVIGATION Navigation by using a bottom bounce sonar pulse to map the contour of the ocean bottom and comparing the contour to computer memories. When the actual contour matches the computer’s memory, the ship’s position is known and the ship has a “fix.” Advantageous since it allows obtaining a fix when deeply submerged without need to slow down and approach the surface. Disadvantages are that it emits an active sonar beam, allowing detection, and is useless when over a sandy flat bottom.

BOTTOM CONTOUR (BE) SONAR Sonar set allowing bottom contour navigation with a secure pulse (narrow frequency, short pulse duration) sonar.

BOTTOM SOUNDING Distance from the keel to the ocean bottom, measured in fathoms using the fathometer or BE sonar.

BOUNDARY LAYER Region of fluid flow around a solid object where the flow is slowed by friction with the surface of the object. Causes drag, slowing the object.

BOURDON TUBE A bent tube of metal that straightens when increasing internal pressure is applied. Used in primitive depth gages.

BOW COMPARTMENT Furthest forward compartment in a Piranha class submarine, containing crew berthing in the upper level and the emergency diesel generator in the lower level.

BOX A rectangular area of ocean, about ten miles wide and thirty miles long. A transiting submarine is required to stay inside the box. The box moves through the ocean at the same speed as its center, called a PLAIN (point of intended motion). Used so that an ASW surface ship does not mistake a transiting U.S. sub for an enemy. Any submarine contact inside the box is assumed to be a friendly. Not used in wartime, when submarine safety lanes are used, entire lanes devoted to transiting U.S. subs.

BRIDGE Small space at the top of a submarine’s sail used for the Officer of the Deck to control the movement of the ship when on the surface. The height allows a better view of the surroundings of the ship.

BRIDGE ACCESS TRUNK Tunnel from the interior of the submarine to the bridge.

BROADBAND Noise containing all frequencies; white noise, such as heard in radio static, rainfall, or a waterfall. Broadband detection range is high for surface ships, which are noisy. Broadband detection range is low for submarines, usually less than five miles, due to quiet submarine designs.

BUBBLES (1) The ship’s angle in degrees, as in the order “five degree down bubble.” A relic of the days when bubble inclinometers were used to measure the ship’s angle. Modern angle indicators take input from the gyro. The old style bubble is retained as insurance against electrical failures. (2) Control. Loss of control is known in slang as “losing the bubble.”

BULKHEAD Seagoing name for a wall. Compartment bulkheads are the reinforced steel walls between compartments, hardened against seapressure so that one flooded compartment will not flood the neighboring compartment.

BURST COMMUNICATION Satellite-to-submarine and submarine-to-satellite radio transmissions using computers to compress messages. Allows high data rates, so that a ream of messages may be transmitted or received in mere seconds.

BUS Electrical term for a collection of loads. Vital bus loads include reactor main coolant pumps and control rod control. Nonvital bus loads are also “vital” and include sonar, fire-control, etc., but are called nonvital since their loss will not immediately cause the loss of the ship.

CAVITATION Noise generated by a ship’s screw. Always generated on surface ships, but only on submarine screws when a ship accelerates. A screw blade moving in the water, like an airplane wing, causes a low pressure region on one side and a high pressure region on the other. The low pressure (suction) side pulls the ship forward while the high pressure side pushes the ship forward. When the low pressure side’s pressure gets too low, the water actually flashes to steam (boils) since the pressure can no longer keep the water molecules together in liquid form. A steam bubble is formed that is moved out into the water. When the steam bubble sees the higher pressure in the water away from the screw, it collapses again into liquid and emits a loud high frequency screech. A dead giveaway that a submarine is accelerating. To minimize noise, a submarine accelerating does so deliberately slowly. When running from a torpedo, in an emergency, the Conn will order maneuvering to cavitate since speed is more important than stealth.

CHAIN REACTION When a nuclear fission reaction causes at least one more fission reaction from the release of neutrons. The fission neutrons leak when subcritical, but when a reactor is critical, the number of fissions is constant since one reaction leads to another.

CHARGE PUMP A high-pressure pump that forces water into the high-pressure nuclear reactor cooling system to make up for any water lost from a rupture or leak.

CHECK VALVES Valves that allow flow only in one direction.

CHICKEN SWITCH One of two levers in the control room that emergency blow the main ballast tanks. So named since they are used when the captain is chicken and can no longer remain submerged. A term sometimes used for the hydraulic levers aft that shut ball valves on seawater systems for isolation of flooding.

CHIEF OF THE BOAT (COB) The most senior non-nuclear chief petty officer aboard, who is administratively responsible for the enlisted men on the submarine.

CINCLANTFLEET Commander-in-Chief, U.S. Atlantic Fleet. Admiral in command of the fleet, who has COMAIRLANT, COMSUBLANT, and COMSURFLANT reporting to him. Little known fact: as a CINC, the admiral has nuclear weapon release authority separate from that of the President. He will out of courtesy not release nuclear weapons without Presidential orders, but is authorized to use his own judgment during an emergency. CINCLANTFLEET also is the name for the organization supporting the admiral’s command.

CIRCLE PATTERN Mark 49 and Mark 50 torpedo search pattern in which the torpedo swims in a circle until it finds the target.

CLAMSHELLS The steel or fiberglass hinged plates that cover the top of the bridge cockpit when rigged for dive and are opened when rigged for surface. When shut, the top of the sail is completely smooth.

CLEAR BAFFLES A maneuver to turn the ship around so that the sonar system can examine the conical slice of ocean previously astern of the ship, the blind spot called the baffles.

CLEAR DATUM Tactical euphemism meaning run away.

CLEARANCE Permission from COMSUBLANT for a submarine to submerge and go to a certain place for a certain mission. Also called a SUBNOTE, the clearance specifies the travel of the box and the PLAIN through the ocean.

CLICK A kilometer per hour.

CLUTCH A device aft of the reduction gear that allows uncoupling the ship’s drive train (main engines and reduction gear) from the shaft, allowing the EPM (emergency propulsion motor) to turn the shaft, and hence the screw, without having to turn the massive main engines. Very similar to the clutch on an automobile.

CO BURNER/CARBON MONOXIDE BURNER A device that combusts carbon monoxide to produce carbon dioxide. CO is able to knock a crew unconscious with low concentrations, so the burners are vital pieces of the atmosphere control equipment.

C0₂ SCRUBBER Atmospheric control equipment that rids the ship of carbon dioxide (from breathing, the diesel, and the CO burner) by blowing it over an amine bed.

COCKPIT The small space at the top of the sail. The bridge.

COMAIRLANT Admiral in command of Naval Aviation in the Atlantic Fleet.

COMMINT Intelligence gained from intercepted enemy communications.

COMMODORE Commander of a squadron of submarines. Usually a Navy captain. For a few years, the old rank of commodore was recommissioned, and commodore was essentially a one star admiral. The admirals complained, wanting to be called admirals. In recent years the rank of commodore has been replaced with the rank rear admiral (lower half).

COMPARTMENT A section of a submarine with hardened bulkheads and the pressure hull as its envelope. Able to withstand almost full crush depth pressure. Separating a submarine into several compartments makes the ship more survivable.

COMSUBLANT Commander Submarines U.S. Atlantic Fleet, the admiral in command of the Atlantic’s submarine force. Also the name of the organization that supports the admiral, including intelligence, liaison, supply, communications, and procurement.

COMSUBRON 7 Commander of Submarine Squadron Seven. Also the name of the organization that supports the commodore.

SUBRON’s physical command includes pier 7 at Norfolk Naval Base and the submarine tender ship Hercules. The Squadron staff and the commodore occupy several 0-level decks of the Hercules.

COMSURFLANT Commander Surface Force U.S. Atlantic Fleet, the admiral in command of the Atlantic’s surface fleet. Also the name of the organization that supports the admiral.

CONDENSER A piece of equipment that converts low pressure steam to water by passing the steam over tubes with cold seawater flowing inside them. The main seawater system exists to pump the seawater through the truck-sized main condensers. The condensate water is pumped back into the steam generators (boilers) to be boiled to steam for use in the turbines for power production and propulsion.

CONN (1) The act of directing the motion and mission of a submarine. Done by the Officer of the Deck, the Junior Officer of the Deck, or the captain. Whoever has the Conn is the conning officer. (2) The elevated periscope stand in the control room where the Officer of the Deck usually conns the submarine.

CONN OPEN MICROPHONE RECORDER (COMR) A black box in the overhead of the control room that records conversations during sensitive operations for use of reconstruction. Submitted with patrol reports after an OP. Monitored in the radio room and sometimes in sonar.

CONNING TOWER The fin on top of a submarine’s hull allowing the ship to be conned safely on the surface. Called the sail in the U.S. Navy.

CONTACT Another ship, detected by visual means, sonar, or radar. A contact can be hostile or friendly.

CONTINGENCY 12 A section in the CINCLANTFLEET SIOP WARPLAN outlining options for a submarine captain when he suspects the United States has been the victim of a decapitation nuclear assault. Boomers and Javelin cruise missile submarines are given the option of launching nuclear weapons at the enemy without orders from Washington, NMCC, or CINCLANTFLEET. Fast attack submarines without land attack weapons are given the option of attacking enemy surface ships and submarines without further orders.

CONTROL COMPARTMENT Bubbleshaped compartment above the main pressure hull of some Russian submarines, where all control activities are centered.

CONTROL ROOM Nerve center of a submarine, where the depth, speed, and combat actions of a submarine are directed.

CONTROLLING ROD GROUP The group of nuclear control rods that are raised and lowered to control reactor temperature or dropped to the bottom of the core during a partial (group) scram.

COOLANT DISCHARGE Discarding reactor coolant (water) overboard. Done during the heatup of a fast recovery startup, when the raising of water temperature from 300 degrees to 500 degrees makes it expand dramatically.

COOLANT LOOP One of two piping loops going from the reactor vessel to the loop’s steam generator (boiler) and then to the loop’s reactor main coolant pumps and back to the reactor vessel. The piping is called the primary coolant system and is highly radioactive, CORE The inside of the reactor’s pressure vessel. The core contains fuel elements including enriched (bomb grade) uranium sheathed in zirconium metal; a moderator to slow down the fission neutrons so they can be absorbed by uranium nuclei to cause more fissions (water is the moderator in a Navy core); and control rods that absorb neutrons so that the reactions and power level can be controlled.

COSMOS Russian communications satellite.

COUNTER ROTATING SCREWS Propulsion method using a screw that turns clockwise with another coaxial screw that turns counterclockwise. Efficiency increased since the first screw’s exit vortex energy is used by the second screw to create more thrust. Disadvantages include complexity of design.

COUNTERDETECTION When submarine A sneaks up on submarine B, the detection by submarine B of submarine A is a counterdetection.

COUNTERFIRE When submarine A fires on submarine B, a counterfire is the launching of a weapon by submarine B at submarine A. COUNTERMEASURES A small object launched by a signal ejector or a torpedo tube designed to decoy an incoming torpedo. Some low-tech countermeasures are bubble generators designed to fool active sonars. More sophisticated countermeasures for use against passive sonar torpedoes are torpedosized noisemakers programmed with the firing ship’s own sound signature, broadcast louder than the firing ship.

COW (CHIEF OF THE WATCH) Member of the ship control team manning the Ballast Control Panel.

CPA (CLOSEST POINT OF APPROACH) The closest range a tracked contact will come to own ship. Prior to CPA the contact is closing. After CPA the contact is opening.

CPO (CHIEF PETTY OFFICER) Enlisted rank somewhat equivalent to sergeant in the Army. Possesses infinite knowledge and wisdom regarding submarines.

CRAZY IVAN A Russian submarine’s maneuver to clear baffles. Due to the Russian submarines frequently being trailed by U.S. subs, the Russians clear baffles suddenly and come back on the reciprocal course. An intimidation tactic designed to deter American boats from trailing too close. The cause of several undersea collisions.

CREEP Property of some metals at elevated temperatures to stretch when failing instead of rupturing or fracturing. Titanium has the property of exhibiting creep at low temperatures.

CREEP DEPTH A titanium submarine’s depth at which the hull begins to fail in creep.

CRITICAL The point that a nuclear reactor’s fission rate is constant without an external source of neutrons. The chain reaction keeps fissions going on using neutrons from fissions.

CRUSH DEPTH The depth that a pressure hull ruptures from seawater pressure.

CSLINST COMSUBLANT Instruction. An administrative document with administrative orders from COMSUBLANT.

CURVE A curve is obtained when a fire-control solution is reached. Derives from the days of manual plots when bearing to a target was plotted against time. After two or three legs, the Z-shaped curve defined a solution to the target.

CUTBACK An automatic reactor protection circuitry action to lower reactor power by driving the controlling control rod group into the core. The cutback allows propulsion to continue while saving the reactor from an overpower meltdown accident. A Navy engineering compromise action between a scram (which eliminates propulsion) and continued criticality, which could lead to a nuclear accident.

CUTBACK OVERRIDE Action to stop a cutback by taking the mode selector switch to the cutback override position, stopping control rod motion inward. Used when a cutback is caused by an instrument failure rather than an actual hazard.

C.O. (COMMANDING OFFICER) Official title of the captain of a ship.

DANCING WITH THE FAT LADY Periscope watch. When rotating the number two periscope (type 18 scope), the observer’s pelvis is pressed up against the hot optical control module of the unit. Physically exhausting when done for hours at a time.

DEBALLASTING SYSTEM Russian alternative to an emergency blow system. Explosive charges are placed in the ballast tanks to blow water out and replace the water with hot gases. Cheaper system than an emergency blow system, but rumored to have worsened Russian emergencies by rupturing the hull instead of blowing out ballast tank water.

DECADES PER MINUTE Measure of speed of increase of reactor power during a startup. A decade increase means that there are ten times as many fission neutrons in the core as before. There maybe several dozen decades between the startup range and the power range. Normal startup rate is one decade per minute (about two to ten times faster than a civilian reactor startup rate). Fast recovery startup rate is 5 decades per minute. Absolute emergency rate is 9 dpm, since the maximum visible on the meter is 10 dpm.

DECK OFFICER Russian equivalent to the American Officer of the Deck.

DELOUSING When a submarine temporarily trails another friendly submarine; done to ensure the first sub is not being trailed by an enemy sub.

DEPLOYMENT Extended submarine OP to a distant OPAREA.

DEPTH CONTROL Ability to control a ship’s depth within a narrow control band. Done either manually, with a computer, or with the hovering system (when stopped). Particularly vital at periscope depth because failure to maintain depth control can cause the sail to become exposed (broach), giving away the ship’s position.

DEPTH RATE Speed of change of depth in feet per second. Vertical speed.

DEPTH SOUNDER Fathometer. Measures distance from the bottom of the ship (keel) to the ocean bottom.

DETECT (Noun) When a torpedo is in search mode, a detect is a positive confirmation that a target is where the solution theoretically shows him to be. When a submarine is discovering a target, a detect is the initial sonar bearing to the broadband noise or the initial sonar frequency of the tonal.

DEUTERIUM Heavy water. Used in nuclear fusion reactors or fusion (hydrogen) bombs.

DIALEX Phone system used on submarines for administrative and unofficial communication.

DISK CRASH The failure of the disk module of the fire-control computer. Memory access and operating system actions are done using the tape module, which is infinitely slower than the disk system. Severe failure, but still allows limited fire-control and weapon launch functions.

DISTRIBUTED CONTROL SYSTEM (DCS) Computer system that controls a complicated process such as a nuclear propulsion plant.

DIVE POINT The point a submarine plans to submerge. Traditionally where keel depth is greater than 600 fathoms.

DIVING OFFICER Officer or Chief who sits aft of the sternplanesman and helmsman. Responsible for depth control.

DOGS Banana shaped pieces of metal that act as clasps to keep a hatch shut.

DOPPLER EFFECT Effect responsible for train whistles sounding shrill when the train approaches and low pitched when the train is past. When a moving platform emits sound waves, the waves are compressed ahead and rarefacted (spread apart) behind the source. The compression of the waves raises their frequency, making a higher note.

DOPPLER FILTER A sonar receiver that blanks out reception of the frequency of transmission of a sonar pulse. The receiver listens only for higher or lower frequency returns, thus screening out stationary contacts and only detecting moving contacts. Used in police radars and torpedo underice active sonars.

DOT STACK Same as a bearing dot stack.

DOUBLE HULL Construction of the pressure hull inside an outer hull. The space between the outer and inner hull is used for equipment and ballast water. Creates a very survivable platform at the cost of weight and expense.

DRAIN PUMP Main component of the drain system. Pumps out bilges of flooding spaces and discharges the water overboard.

DUTY OFFICER Essentially the Officer of the Deck when the ship is tied up at the pier or in drydock.

D/E (DEFLECTION/ELEVATION) The spherical array of the BAT-EARS sonar suite has hydrophone sonar receivers placed over most of its surface. A sound received on the upper surface (high D/E angle) means the contact is above the submarine or its noise is bouncing off the ocean above. A sound received at low D/E is either reflected from the ocean bottom or directly transmitted from beneath the submarine.

ELECTRIC PLANT CONTROL PANEL (EPCP) A console in the maneuvering room that controls the electrical distribution of the ship including the turbine generators and the battery.

ELF (EXTREMELY LOW FREQUENCY) Long wave radio waves capable of penetrating deeply into the ground and underwater. Requires large high power land based antennae and has very low data rates (taking several minutes to transmit one letter or number). Usually used to call a submarine up to periscope depth to receive a burst of communication from the satellite.

EMBRITTLEMENT A reactor’s pressure vessel is impacted by trillions of neutrons, altering the physical structure of the metal. The steel vessel becomes brittle and fractures easily when subjected to sudden temperature changes, like a frozen coffee mug shatters when hot coffee is poured in.

EBMT BLOW Emergency main ballast tank blow.

EMERGENCY BLOW Blowing the water out of the main ballast tanks using ultrahigh-pressure air. Empties ballast tanks in seconds, lightening the ship, allowing the ship to get to the surface in an emergency such as flooding.

EMERGENCY COOLING (XC) A system that uses a seawater heat exchanger to cool the nuclear reactor when flow through the core is lost. Uses natural convection flow, which is flow motivated by the tendency of hot water to rise and cold to sink.

EMERGENCY DEEP An emergency procedure used at periscope depth to avoid collision with a surface ship. Involves cavitating, flooding a depth control tank, and putting a diving angle on the ship to get deep in mere seconds. Designed to avoid hull rupture from collision with a surface ship that cannot see the sub at PD. Era of super tankers makes this a vital procedure because super tankers have so much oil volume forward of their engines that they are quiet as a sailboat and are often undetected by sonar.

EMERGENCY HEATUP RATE Emergency procedure used on startup when heating a nuclear reactor after a scram. Instead of a nice slow warmup at a half degree per minute or one degree per minute, the plant is heated up at up to several hundred degrees per minute to save the ship, ignoring the risk of a possible vessel rupture from thermal stress.

EMERGENCY PROPULSION MOTOR (EPM) A large DC motor aft in the engineroom, capable of turning the shaft to achieve 3 knots using battery power alone. An electricity hog.

EMERGENCY SSTG WARMUP Emergency procedure to get a turbine generator to make power within seconds from its cold condition after a reactor scram. Done to achieve power quickly, ignoring the risk of turbine destruction, case rupture, and major steam leak.

ENGINEROOM Largest and furthest aft compartment on a U.S. submarine. Holds the maneuvering room, propulsion and electrical turbines, main condensers, numerous pumps, evaporator, air conditioners, reduction gear, clutch, EPM, and shaft seals.

ENSIGN Lowest officer rank. Also a flag flown aft when the ship is tied up.

EO (ELECTRICAL OPERATOR) Enlisted nuclear qualified watchstander who mans the Electric Plant Control Panel and reports to the EOOW.

EOOW (ENGINEERING OFFICER OF THE WATCH) Nuclear qualified officer who runs the nuclear power plant. Responsible to the OOD for propulsion and propulsion plant damage control.

ESCAPE POD Device used on Russian submarines to escape a sinking ship.

ESCAPE TRUNK A spherical airlock used on American nuclear submarines. The device can be used to make emergency exits from a sub sunk in shallow water. Principally used for divers to lock in or lock out.

ESM MAST An antenna that is raised to allow detailed analysis of enemy radar or radio signals. Supplements the equipment installed on the periscope.

ESM (ELECTRONICS SURVEILLANCE MEASURES) The gathering of intelligence through the analysis of enemy signals, including radars and radio transmitters.

EVAPORATOR Device that evaporates seawater using steam heat. The vapors are condensed and used as potable (drinking) water or steam plant/reactor plant makeup water. The plant comes first.

EWS (ENGINEERING WATCH SUPERVISOR) A Chief who is a roving supervisory watchstander in the engineering spaces. Reports to EOOW.

EXPLOSIVE BOLTS A hollow fastener with an explosive charge inside for quick disconnection. Used in rocket motor stages and escape pod latches.

EXTERNAL–COMBUSTION ENGINE Engine in which the fuel and oxygen bum in a chamber remote from where the work is done. Examples include jet engines and oil-burning steam plants. As opposed to internal combustion engines where the fuel is burned where the mechanical work takes place, as in an automobile engine.

FAIRWATER PLANES Winglike surfaces protruding from the sail of a submarine, used for depth control. Can be rotated to a vertical position for breaking through polar ice.

FAMILYGRAM Short three line personal radio message from a crewmember’s family, transmitted by COMSUBLANT when a ship is on a deployment. Family typically gets one message every six weeks.

FAST ATTACK SUBMARINE An SSN, a submarine designed to be small, light, quiet, fast, and lethal. Carries torpedoes to sink surface ships and other submarines. Carries cruise missiles for anti-ship warfare and for land attack. Used also as a coven intelligence gathering platform. Can put covert troops ashore using the escape trunks. Capable of months of submerged, undetected operations.

FAST LEAK A rather nasty leak from the primary coolant system of a nuclear reactor. If not isolated, will empty the water from the core and lead to a meltdown, and possibly to a prompt critical rapid disassembly.

FAST NEUTRONS Neutrons emitted by uranium nuclei undergoing fission. Mostly useless for causing another fission reaction since they want to leak from the core. Water (moderator) slows the fast neutrons down through collisions with water molecules. The slow (thermal) neutrons can then be accepted by a uranium nucleus to cause another fission. Under some conditions, uranium can be critical on fast neutrons. One example is a bomb undergoing a nuclear explosion. A second is a core in a reactivity accident such as a control rod jump, where the core becomes prompt crit’cal, critical on the fast neutrons that are emitted “promptly” by the fission reaction.

FAST RECOVERY STARTUP Emergency procedure to recover from a reactor scram at sea, using a 5 decade per minute startup rate and abbreviated turbine warmups. One of the compromises between ship safety (requiring the reactor be up for propulsion) and reactor safety (requiring a scram if there is the slightest reactor fault).

FATHOM Unit of depth equal to six feet.

FATHOMETER Bottom sounding sonar that directs an active sonar pulse down to the ocean bottom and measures the time for the pulse to reflect back and hence the distance to the bottom. New units transmit a secure pulse, using a short duration random high frequency pulse.

FBM Fleet ballistic missile submarine. Official name of a boomer.

FINAL BEARING AND SHOOT Order of the captain to shoot a torpedo after he takes one last periscope observation of a surface target.

FIRE-CONTROL SOLUTION A contact’s range, course, and speed. A great mystery when using passive sonar. Determining the solution requires maneuvering own ship and doing calculations on the target’s bearing rate. Can be obtained manually or with the fire-control computer.

FIRE-CONTROL SYSTEM A computer system that accepts input from the periscope, sonar, and radar (when on the surface) to determine the fire-control solution. The system also programs, fires, steers, and monitors torpedoes. If a ship is cruise missile equipped, the system will program and fire the missile.

FIRE-CONTROL TEAM A collection of people whose task is to put a weapon on a target. Includes the sonar operators, OOD, JOOD, Captain, XO, fire-control operators on Pos Two, Pos Three, the firing panel, and the manual plotters (geographic, time-bearing time-range, and time-frequency).

FIRING PANEL A console section between Pos Two and Pos Three. The vertical section is a tube/weapon status panel. The horizontal section has the trigger, a lever used to fire a torpedo or cruise missile.

FIRING POINT PROCEDURES An order by the captain to the fire-control team to tell them to prepare to fire the weapon, done during a deliberate approach when the solution is refined, as opposed to a Snapshot. The solution is locked into the weapon and the ship is put into a firing attitude.

FIRSTIE A first class midshipman at Annapolis. A senior.

FISSION A nuclear reaction during which a uranium or plutonium nucleus is split apart after the absorption of a neutron. Releases two to three neutrons, two nuclear fragments, and 200 megaelectron volts of energy.

FIX A ship’s position. Determined by visual triangulation or radar when close to land on the surface, or by NAVSAT or BE sonar when at sea.

FIX ERROR CIRCLE The circle that the ship could be in as a result of time since the last fix, steering errors, speed errors, etc.

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.

FLOATING WIRE ANTENNA A buoyant wire trailed from a submarine’s sail used to stay in passive radio communication when the ship is deep. Tends to snag fishing boats. Seagulls love to ride on them. Not generally used by SSN’s.

FLOODABLE VOLUME The amount of a compartment that can flood before it causes the ship to sink.

FORWARD GROUP The main ballast tanks forward of the operations compartment. During an emergency blow, all six of these ballast tanks are blown dry simultaneously.

FRAME Hoops of steel or titanium that serve as the skeleton for the pressure hull.

FRAME 57 The frame between the operations compartment and the reactor compartment on a Piranha class submarine. The start of the engineering spaces. Anything beyond Frame 57 is called “back aft.”

FREQUENCY GATE A narrow range of frequency that the sonar is tuned to listen to.

FUEL ELEMENT An assembly of uranium with zirconium cladding in a nuclear core. The uranium heats the water, making steam in the steam generators, allowing power production in the turbines.

FULL POWER LINEUP Electric plant lineup when the reactor is critical and self-sustaining. Both turbine generators are at 3600 RPM and are supplying power to the ship’s loads. The battery is not discharging.

FULL RUDDER When the rudder is turned 30 degrees.

FULL SCRAM When all control rods (not just the controlling group) are pushed to the bottom of the core. It takes much longer to recover from a full scram than a group scram.

FULL SPEED Maximum speed of a U.S. submarine with slow speed reactor main coolant pumps running the reactor at 50 % power. A Piranha class does about 25 knots at full.

FUSION A nuclear reaction in which several light nuclei come together and release tremendous quantities of energy. Usually requires initial temperatures of several thousand degrees.

G A measure of acceleration. The acceleration due to gravity is one g. Two g’s is twice, etc.

GAMMA RADIATION Electromagnetic radiation released in a nuclear reaction. Generally similar to X-rays.

GEOGRAPHIC PLOT (1) A manual plot saved from World War II submarine days using the plot table to deduce a fire-control 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 firecontro) 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.

GEOSYNCHRONOUS SATELLITE A satellite orbiting at an altitude of about 33,000 miles. The orbital velocity matches the earth’s rotational speed, making the satellite stationary with respect to the earth’s surface. Ideal for communication satellites.

GI-UK GAP (GREENLAND-ICELAND-UNITED KINGDOM GAP) The northern entrance to the Atlantic, choked by Greenland and Iceland to the northwest and Great Britain to the east. Any sortie of Russian Northern Fleet units would need to pass north of Norway, then south through the GI-UK gapGMT (GREENWICH MEAN TIME) A worldwide time standard using the time at longitude zero at Greenwich, England. Also called Zulu time.

GO CODE Slang for a nuclear release message to units ordered to fire nuclear weapons.

GPS (GLOBAL POSITIONING SYSTEM) A series of satellites and shipbome receivers enabling extremely precise navigation fixes. Also called the NAVSAT.

GRASS/RADAR GRASS A region within about 50 to 100 feet of the ground that surface search and air search radars are unable to penetrate due to ground clutter. An aircraft or missile flying in the grass can sneak up to its target without radar detection.

GREEN BAND Normal limits for T-AVE during critical reactor operation. Between 480 and 500 degrees IF.

GROUP ONE One of three control rod groups in a Naval S5W/S3G Core 3 core. During about half of core life these control rods control reactor temperature and power level.

GROUP SCRAM A reactor scram using only the few control rods in the controlling rod group. Enough negative reactivity to shut down the reactor for several hours, but not so much that recovery is difficult.

GUIDANCE WIRE A neutrally buoyant wire streamed from the rear of a Mark 49 or 50 torpedo allowing communication between the weapon and the fire-control system. Used to pass steer commands from ship to torpedo and information about the target from torpedo to ship, GYRO/GYROSCOPE Electrical compass using a rapidly spinning gyroscope.

HAFNIUM Element used in Navy control rods. Acts as a black hole for neutrons. Without neutrons, fission reactions stop, and a core is shutdown.

HALF POWER LINEUP Electric plant lineup when the reactor is critical and self-sustaining. One turbine generator is at 3600 RPM and supplying power to the ship’s loads. The battery is not discharging.

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 reduction 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.

PATTERN CHARLIE The point in space and time when a CINC’s airborne command post is a safe distance from its base, so that it is no longer vulnerable to nuclear destruction. The CINC can then take over from an operational commander in a bunker.

PCO WALTZ A melee situation where two submarines are aware of each other in a combat situation. fire-control 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. Term originates from Prospective Commanding Officer School at Groton, Conn., where many subvs-sub exercises are done.

PD (PERISCOPE DEPTH) An operation when the ship comes shallow enough to see with the periscope. Certain operations can only be done at periscope depth by decree of the Submarine Standard Operating Procedures manual. Such items include steam generator blowdown, shooting trash from the TDU, and blowing sanitary. Some things can only be done at PD, including radio reception of satellite broadcasts, reception of a NAVSAT pass, and ESM activities. Slows the ship down since high speeds can rip off the periscope. Dangerous operation since quiet surface ships can get close without being detected by sonar. See Emergency Deep.

PHOTOINT Photographic intelligence, such as the interpretation of satellite photos.

PILOT A person who has detailed knowledge and experience of a port and approach waterways. Taken on prior to entering or exiting port to serve as an advisor to the captain.

PLAIN (POINT OF INTENDED MOTION) The center of the box. The moving point in the ocean that a transiting submarine stays within a predefined range of at all times. See Box.

PING An active sonar pulse.

PIRANHA CLASS The SSN-637 class of submarines, headed by the lead ship of the class, the USS Piranha. Press release from the program at the launch of the USS Piranha reads: “Piranha is a streamlined, highly advanced, and maneuverable antisubmarine warfare platform which uses the most advanced technology to accomplish her mission… Super quiet, deep diving, and swift. Piranha is one of the most capable warships of the United States Fleet.”

PLEBE A first year man at the U.S. Naval Academy at Annapolis.

PLOT TABLE A glass topped boxlike table that has a mechanism that moves in scale to the ship’s motion in the sea. Table accepts input from the ship’s gyro and speed indicator to do this. When tracing paper or charts are taped to the table top, the ship’s motion can be plotted and recorded against time. Used for the geographic manual plot to determine contact solution. Also used to map polynyas. Ancient low-tech method of doing all these things, it has the advantage of not relying on computers, and is thus “bulletproof.”

POLYMER A chemical formed of long chainlike molecules.

POLYMER INJECTION The injection of a polymer into the boundary layer of a submarine at the nosecone. The slippery liquid reduces the skin friction of the ship, reducing the drag. The result is the ability to dramatically increase ship’s top speed for short periods of time. Ideal for torpedo evasion.

POLYNYA Thin spot in the polar icecap where a submarine can surface by breaking through the ice.

POOPY SUIT Underway uniform worn by American submariners. Usually cotton coveralls. Origin unknown.

PORK CHOP Nickname of the Supply Officer.

POSITION ONE (POS ONE) Furthest forward console of the Mark I fire-control system. Usually set up with the captain’s and XO’s guess solution to the contact or displays the geographic display for a God’s-eye view of the sea.

POSITION THREE (POS THREE) Furthest aft console of the Mark I fire-control system. Usually set up to program torpedo tubes and weapons.

POSITION TWO (POS TWO) Mark I fire-control console between Pos One and the Firing Panel. Usually set up on the Line-of-Sight mode so that the Pos Two officer can come up with his own independent fire-control solution under the XO’s supervision.

POSITIVE DISPLACEMENT PUMP A pump that uses pistons, diaphragms, or moving rotors to force liquid from a low pressure area to a high pressure area.

POWER RANGE Nuclear power level above the intermediate range. In the power range, steam can be produced by the reactor for propulsion.

PRECIPITATOR A device that removes particles and oil droplets from the air by passing the air over a highly charged set of plates or wires.

PRESSURE HULL Hardened steel section of a submarine able to take sea pressure at depth. The “people tank.”

PRESSURIZED WATER REACTOR A PWR produces power using water at high temperature and pressure as both a moderator and coolant. Also uses a primary water coolant loop that keeps the radioactivity confined. A secondary system, the steam system, takes energy from the primary coolant and uses it for propulsion — the secondary system is not radioactive. As opposed to a BWR, boiling water reactor, that acts as a reactor and boiler, in which the reactor’s coolant is used in the turbines, making the drive train’s internals radioactive.

PRESSURIZER Tank in the primary coolant system that keeps the water in liquid form even up to 500 degrees by using heaters and raising the water in the pressurizer to even higher temperatures and pressures.

PRESSURIZER LEVEL The level of the pressurizer tank is the main indication of the amount of primary coolant in the primary coolant system. Large changes in core temperature can raise or lower the level due to thermal expansion or contraction of the water. A loss-of-coolant accident is detected by a falling pressurizer level.

PREUNDERWAY CHECKLIST Set of checklists used to get a submarine under way, including valve lineups and switch position checks. Considered of equal complexity and scope to a Space Shuttle countdown checklist.

PRIMARY COOLANT SYSTEM The piping system that circulates primary coolant from the reactor core to the steam generators (boilers) using reactor main coolant pumps. As opposed to the “secondary” coolant, the steam going from the boilers to the turbines for propulsion.

PRIORITY A level of urgency of a radio message below IMMEDIATE and above ROUTINE. Reception guaranteed on the same day.

PROMPT CRITICAL Under some conditions, uranium can be critical on fast neutrons instead of thermal neutrons. One example is a bomb undergoing a nuclear explosion. A second is a core in a reactivity accident such as a control rod jump, where the core becomes prompt critical, critical on the fast neutrons that are emitted “promptly” by the fission reaction. A core that is prompt critical is milliseconds from either a steam explosion or a prompt critical rapid disassembly.

PROMPT CRITICAL RAPID DISASSEMBLY Polite term for the unlikely event of a core undergoing a nuclear explosion.

PROPULSOR Sophisticated screw that uses ducting and multistage water turbine blades for propulsion instead of a conventional screw. Similar to a water jet. Extremely quiet and nearly impossible to cavitate. Disadvantage includes slow response and acceleration due to relatively low thrust compared to conventional screws.

P.A. CIRCUIT ONE Ship wide Public Address announcing system.

P.A. CIRCUIT SEVEN Speaker announcing system used between the Conn, Maneuvering, the bridge, and the torpedo room.

P.A. CIRCUIT TWO Similar to P.A. Circuit One, except that it only announces in the engineering spaces (aft of frame 57).

RANGE Distance to a contact.

RANGE GATING The action of an emitter of active sonar pulses. The ship being tracked can tell how close the pinging platform is by the time between pulses, assuming the transmitter does not ping the second pulse until it receives a return ping from the first pulse. The closer the pinging object gets to own ship, the shorter the interval between pings.

REACTOR Nuclear core. An assembly of fuel elements containing U-235, control rods, shielding, and inlet and discharge of primary coolant. Heat source that allows steam to be generated in the steam generators to produce propulsion and electricity.

REACTOR COMPARTMENT Compartment housing the reactor, pressurizer, steam generators, and reactor main coolant pumps. Access fore and aft is through a shielded tunnel, since anyone inside the compartment when the reactor is critical would be dead within a minute from the intense radiation.

REACTOR MAIN COOLANT PUMPS Massive pumps, each consuming between 100 and 400 horsepower, that force main coolant water through the reactor and then to the steam generators. Three are in each main coolant loop. Special design allows zero leakage.

REACTOR PLANT CONTROL PANEL (RPCP) Control panel in the maneuvering room where the Reactor Operator controls the reactor.

REACTOR PROTECTION Circuitry containing safety interlocks and control functions preventing reactor damage in an accident.

REACTOR VESSEL Heavy steel shell housing the reactor core.

REAR GUARD SONAR New Russian passive and active sonar that looks astern into the baffles. Mounted in the aft section of the pod atop the rudder of the Project 985 (Kaliningrad or OMEGA) class Russian submarines. Eliminates need to do baffle clearing maneuvers.

RECONSTRUCTION Six-hour period following a watch when an enemy submarine is trailed. The offwatch fire-control team meets in the officer’s wardroom and compares data from charts, geo plots, computer readbacks, and logs, in an effort to “get the story straight” for the patrol report. Conflicting information is resolved during reconstruction.

REDUCTION GEAR The mechanism that converts the high RPMS of the two main engines (propulsion turbines) to the slow RPM of the screw. Solves the problem of how to get two turbines to drive a single screw. Also solves the problem of how to let the main engines rotate at high RPM where they are efficient while letting the screw rotate at the low RPM where it is efficient. Unfortunately, the reduction gear is one of the noisiest pieces of equipment aboard.

RELAY Electrical device that acts as a smart switch.

RELIEF VALVE A spring loaded valve that will open and relieve the pressure on a tank or vessel instead of allowing the tank to rupture or fail.

REM Roentgen Equivalent Man. A unit of radiation dosage that takes into account tissue damage due to neutron radiation. Convenient since it allows gamma, alpha, and neutron radiation to be measured with the same units. 1000 rem will kill. 500 rem may kill. Yearly dose for submarine personnel is restricted to less than 25 to 100 millirem.

RIG FOR BLACK Submarine term meaning “turn off the lights in the control room.”

RIG FOR COLLISION A ship wide lineup consisting of shutting hatches in bulkheads and shutting hardened ventilation dampers in bulkheads to minimize possible risk to the ship during a collision. Generally same as rig for flooding.

RIG FOR DIVE A detailed valve and switch lineup done in preparation to dive. Initially done by a dolphin-wearing enlisted man and checked by a dolphin-wearing officer.

RIG FOR FLOODING Similar to rig for collision. Bulkhead hatches and ventilation dampers are shut to isolate each compartment from the neighboring compartment. Ship is buttoned up to ensure maximum survivability.

RIG FOR 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.

RIG FOR WHITE Submarine term meaning “turn on the lights in the control room.”

TO (REACTOR OPERATOR) Nuclear trained enlisted man who mans the Reactor Plant Control Panel and reports to the EOOW.

ROUTINE A message priority below PRIORITY. Delivery assurance in weeks or months.

RULES OF ENGAGEMENT A formal manual detailing what actions a U.S. vessel may take in response to enemy actions, such as an intentional collision by an enemy vessel in peacetime. In general, the rules require that no weapon may be shot unless the enemy ship has already launched a weapon.

RUN-TO-ENABLE Initial torpedo run taking it away from own ship. During the run-to-enable, the warhead is not armed and the sonar is not operational. When the run-to-enable is complete, the weapon activates the active or passive sonar and swims the search pattern. The warhead is not armed until it has a detect on the target.

R-114 AIR CONDITIONER Two air-conditioning units that control the high temperatures and humidity caused by the steam plants. Ship is air-conditioned to allow electronic equipment to function, not for creature comfort.

SAFETY LANES Special routes for submarine transit in time of war. Submarines detected by U.S. forces inside these lanes are assumed to be friendly.

SAIL Conning tower. Named because, unlike the conning towers of World War II diesel boats, which were misshapen and asymmetrical, modern nuclear submarine conning towers are smooth fins with square profiles when viewed from the side. Someone called it a sail in the distant past and the term became official.

SCI (SPECIAL COMPARTMENTED INFORMATION) A classification of information separate from the Confidential/Secret/Top Secret system. SCI information is compartmented or sectioned, so that no one person has the full story. Capture or compromise of one compartment of the information will be damaging but not catastrophic. SCI information is usually so sensitive that it is generally considered a higher classification than Top Secret. SCI is also information that compromises intelligence methods and sources.

SCRAM An emergency shutdown of a nuclear reactor, done by driving control rods to the bottom of the core using springs.

A term left over from the 1940s when primitive lab reactors had a single control rod suspended by a rope. An emergency shutdown would be done by cutting the rope and letting the rod drop by gravity. The safety man was called the Safety Control Rod Ax Man — hence SCRAM.

SCRAM BREAKER A circuit breaker that interrupts power to the latching electromagnets of the control rod drive mechanisms. When the breaker opens, electrical power to the electromagnets is shut off, the magnets lose their magnetism, and the latches of the rods open, allowing springs to drop the rods to the bottom of the core.

SCRAM SETPOINTS The power level that will result in the protective circuits scramming the reactor. There are also setpoints for amount of flow through the core and core pressure.

SCRAMBLED EGGS The gold branches of leaves sewn onto the brim of a senior officer’s cap.

SCRUBBER C0₂ scrubber. Atmospheric control equipment that rids the ship of carbon dioxide (from breathing, the diesel, and the CO burner) by blowing it over an amine bed.

SEA TRIALS Post construction shakedown cruise of a ship. Done to ensure the equipment lives up to the specifications and that the ship is ready to perform its mission.

SEARCH CONE A cone of ocean extending forward from the nosecone transducer of a torpedo. Anything inside the cone can be detected and homed on.

SEAWOLF CLASS Newest class of American fast attack submarines, the successor to the Los Angeles class.

SECTION TRACKING TEAM A fire-control team stationed to man the plots and fire-control system when tracking a hostile contact for extended periods of time. Modified battle stations. So named because each watchsection (similar to a shift) has its own tracking team.

SECURE PULSE FATHOMETER A fathometer (bottom sounder or bottom contour sonar) that bounces a downward focused secure pulse off the ocean bottom to determine depth below the keel. Pulse is secure because it is short duration and high frequency. High frequencies are quickly attenuated by the ocean.

SELF-OXYDIZING FUEL Fuel such as hydrogen peroxide that contains its own oxygen. Needs only a spark to react and explode violently. Capable of burning underwater. This fuel is frequently used in torpedoes. Its use makes a fire in the torpedo room that much more hazardous.

SELF-SUSTAINING (1) When a jet engine’s turbine has enough power produced to turn the compressor shaft and sustain engine operation. (2) When a nuclear reactor’s steam plant is producing enough electrical power to power its own reactor coolant pumps and electrical circuitry (taking about 10 % power). The ship can then divorce from shorepower.

SES (SONAR EQUIPMENT SPACE) A room in the operations compartment taken up by large electrical cabinets containing power and signal circuits used by the BAT-EARS sonar suite.

SEWER PIPER Another derogatory term for submariner, used by aviators and surface sailors.

SHAFT SEALS The mechanism used to allow the screw’s shaft to penetrate the aft bulkhead of the engineroom without seawater leaking in. Furthest aft point inside the ship.

SHAPED CHARGE An explosive charge that is designed to focus the energy of explosion in a particular direction. Used to break through tank armor and double submarine hulls.

SHARKTOOTH SONAR Slang name for the AN/BQS-8 underice sonar. The transducers are in the forward edge of the sail. Sonar is active, transmitting a high frequency police siren sound, able to transmit and receive simultaneously to chart ice obstacles ahead of a submarine under ice. Also includes a network of topsounders on the sail and hull to look up to find distance to overhead ice and ice thickness. Named SHARKTOOTH because the emitted frequency, when plotted against time, resembles a series of ramps, like shark teeth.

SHIP CONTROL OFFICER Russian equivalent to a helmsman, except the watchstander is an officer directing a highly automated distributed control system that controls the motion of the ship. Reports to the Deck Officer.

SHIP CONTROL PANEL (SCP) The console from which the ship’s depth, course, and speed are controlled. On American submarines, this console resembles a 747 cockpit, with the Sternplanesman on one side, the Helmsman on the other, and the Diving Officer behind and between them. On Russian submarines, the console is the control station for the automated distributed control system that directs the motion of the ship.

SHIP CONTROL TEAM The watchstanders manning the Ship Control Panel, including the Sternplanesman, the Helmsman, and the Diving Officer. Sometimes includes the Chief of the Watch, off to the port side at the Ballast Control Panel.

SHIPS INERTIAL NAVIGATION SYSTEM (SINS) A multimillion-dollar complex navigation system using a sophisticated gyroscope and support electronics to estimate the ship’s position accurately at any time.

SHOCK WAVE An instantaneous change in fluid properties (a disturbance) that travels outward at the speed of sound in the fluid (sonic velocity). Examples include a sonic boom and the shock wave from a nuclear blast.

SHOOT ON GENERATED BEARING Captain’s order to shoot a torpedo based on the fire-control solution’s estimate of where a target should be, not on the last actual bearing from sonar (See Match Bearings and Shoot). Generally considered best way to shoot with the Mark I fire-control system. When ordered, the fire-control team locks in the fire-control solution to the target, and when the torpedo reports back, the captain is given one last chance to say either “Shoot” or “Check fire.”

SIDESCAN SONAR Sonar used to examine objects on the ocean bottom. Used to find the Titanic and wreck of the USS Stingray.

SIGINT Signal intelligence. After intercepting an enemy radar, the emitting platform can be identified.

SIGNAL EJECTOR A small torpedo tube used to eject Hares (for signalling surface ships), communication buoys (which can transmit hours after the ship has cleared datum; also used for SUBSUNK buoys), and countermeasures (torpedo decoys).

SIGNAL-TO-NOISE RATIO (SNL) How loud a contact is relative to the surrounding ocean noise. Measured in decibels.

SIOP WARPLAN The Top Secret plan for waging a major sea war, including the use of nuclear weapons. SIOP stands for Single Integrated OP-Plan.

SKIMMER Derogatory term for a surface ship or sailor of a surface ship. Surface ships only skim the surface.

SKIPJACK CLASS Early fast attack submarine class that was the first to feature a streamlined cylindrical hull.

SLBM Submarine launched ballistic missile.

SNAKE PATTERN A torpedo search pattern in which the torpedo wiggles, tracing a snake shaped pattern. Enables narrow search beam to cover more ocean by forcing the torpedo to look on either side of its heading.

SNAPSHOT A quick reaction torpedo shot, usually only done when fired on first.

SNCP (SPECIAL NAVY CONTROL PROGRAM) Top Secret series of coven submarine operations.

SNORKEL A mast designed to bring air into the submarine so that the air-breathing diesel generator can use it for combustion when the reactor is scrammed.

SOLENOID An electrical device that causes motion by the action of an electromagnet. Used in remotely actuated valves.

SOLUTION A contact’s range, course, and speed. A great mystery when using passive sonar. Determining the solution requires maneuvering own ship and doing calculations on the target’s bearing rate. Can be obtained manually or with the fire-control computer.

SONAR SYSTEM A system of hydrophone/transducer arrays, computers, and displays enabling a submarine to determine what is in the water surrounding it, including other ships.

SONIC VELOCITY The speed of sound waves.

SONOBUOYS Small objects dropped from, ASW aircraft that float on the surface and listen to the ocean below, then transmit that information up to the aircraft. A method of giving an aircraft sonar capability.

SOPA Senior Officer Present Afloat or Senior Officer Present Ashore.

SORTIE An exodus of a group of ships from a port or anchorage.

SOSUS Sound Surveillance System. A network of underwater passive hydrophones and data relay cables buried in secret locations in the Atlantic to track enemy submarines. Triangulation gives enemy submarine positions accurate enough to know their approximate location but not accurate enough to fire on them, even with nuclear weapons.

SOUND SIGNATURE The collection of characteristic sounds, both broadband and narrowband tonals, that uniquely identify a class of ship, and sometimes, the exact ship itself.

SOUNDING The depth beneath the keel as measured by the fathometer.

SOURCE RANGE CHANNEL SELECTOR SWITCH A rotary switch on the Reactor Plant Control Panel that energizes or deenergizes certain nuclear instruments and turns on or off some reactor protection circuits.

SPEED OF ADVANCE (SOA) The speed the ship plans to go during transit. Also the speed of the PLAIN or box.

SPHERICAL ARRAY A sphere in the nosecone of a submarine fitted with transducers over most of its surface to be able to hear in all directions (except the baffles). Useful since it not only tells the bearing to an incoming noise, but also its D/E (deflection/elevation). The D/E can give clues that the sound is relayed via bottom bounce or surface bounce, or even that a close contact is deeper or shallower than own ship.

SPIN UP Start the gyro and computer system of a weapon in preparation for launch.

SPL (SOUND PRESSURE LEVEL) A detailed recording of an enemy submarine’s sound signature obtained by covertly driving an attack submarine in circles around it with a special tape recorder energized. Very dangerous operation requiring approaches to within 10 feet of the enemy hull. Risk of collision is great, but intelligence gained is considered worth the risk.

SQUADRON An organization of about a dozen submarines of the same class under the command of the Commodore. The Squadron usually owns the piers, the tender ship, and a torpedo recovery salvage ship. Squadron commander (Commodore) has only administrative control over the submarines — operational control at sea is done by COMSUBLANT.

SQUIGGLE (SGWLC) Steam generator water level control system.

SSBN A boomer. Literally stands for Submersible Ship, Ballistic missile. Nuclear.

SSN A fast attack submarine. Literally stands for Submersible Ship Nuclear.

SSTG’S (SHIP SERVICE TURBINE GENERATORS) The two turbines aft that turn the ship’s electrical generators and provide electrical power.

STANDARD SPEED Speed between All Ahead Two Thirds and All Ahead Full. Gives about 18 knots.

STAND-DOWN Rest and relaxation period for an attack boat crew after an extended 4, 5, or 6 month deployment.

STARTUP RANGE Lowest reactor power level, in which neutrons are generated by radioactive decay and occasional spontaneous fissions.

STARTUP RATE The speed, in decades per minute, that reactor power level is changing. Positive startup rate means power level is increasing. Negative means the power level is decreasing. See Decades Per Minute.

STARTUP RATE SCRAM A scram caused by a high startup rate. Setpoint is about 9 decades per minute.

STATION NUMBER ONE Position off the Russian northern coast used by either a submarine waiting in ambush in wartime or a coven intelligence gathering ship in peacetime. Location coordinates are in the SIOP WARPLAN.

STATUS BOARD A white board in the control room used to indicate the status of miscellaneous things of interest to the OOD such as torpedo tubes (empty, flooded, door open, or warshot loaded), time of sunrise, etc.

STEADY A report from the helmsman that the ship is on the ordered course and is not turning.

STEAM EXPLOSION One possible result of a reactor overpower accident, in which too much heat is added to the coolant in a short time. The water expands into steam, and the pressure rises dramatically, finally breaching the reactor vessel, causing it to physically explode.

STEAM GENERATOR A large heat exchanger with superhot primary coolant flowing inside tubes, with cold water from the condensers pumped in the bottom. Primary coolant boils the water to steam for use in turbines. Also called a boiler.

STEAM LEAK, MAJOR When one of the large steam pipes ruptures in the engineroom or AMR 2. Result is rapid cooking of engineering crew unless the leak is isolated using MS1 or -2 valves. Steam leaks are also dangerous because they will overpower the reactor.

STEAM PLANT CONTROL PANEL (SPCP) Console in the maneuvering room that monitors the steam plant. Has the large throttle wheel in front that controls the speed of the main engines. Manned by the throttleman.

STERNPLANES Horizontal control surfaces at the tail of a submarine. Similar to the elevator tail surfaces of an aircraft, the sternplanes cause the ship to rise or dive.

STERNPLANESMAN Enlisted watchstander in the Ship Control Party who controls the sternplanes at the Ship Control Panel.

STRAIGHT BOARD Indications on the Ballast Control Panel showing green bars, indicating that all hatches and vents are shut — final announcement indicating ship is ready for dive.

SUBEX Submarine exercise.

SUBMERSIBLE Small deep-diving submarine designed for short trips to the ocean bottom to gather data. May be manned or a robot.

SUBROC Submarine launched rocket with a nuclear depth charge. Obsolete and eliminated since analysis indicated it would severely damage the firing ship due to the nuclear blast.

SUBSUNK An emergeicy transmitter that releases from a submarine hull autom; i.cally at a certain depth that calls a distress signal to the satellite that a submarine is sinking. System taken out of service for fear of it going off mistakenly, giving away the ship’s position.

SUCKER An emergency air breathing mask for use during toxic gas emergencies or radioactive contamination release to the submarine’s atmosphere.

SUPERCRITICAL A condition of a nuclear reactor when power level is increasing and each fission neutron generation’s population is exceeded by the next generation’s.

SURFACED-AT-ICE Ship rigged to stay for a long period of time surfaced at a polynya. Ballast tanks are partially filled with air and monitored.

SUSTAINER ENGINE The jet engine of a cruise missile. It sustains continued flight.

SYNCH A radioman’s term meaning the ship’s radio equipment is tuned and receiving radio signals from the transmitter.

TAPE MODE A fire-control casualty condition in which the tape module is used as the operating system instead of the disk module. Reduces speed and capability of the Mark I fire-control system.

TARGET ONE The designation of a sonar, radar, ESM, or visual contact as a target to be fired upon or tracked.

TARGET ZIG A term used to describe a target’s maneuver, either a turn, speed change, or both. Requires the ship to do more TMA to get a new solution.

TDU (TRASH DISPOSAL UNIT) A vertical torpedo tube used to jettison garbage overboard. Garbage is first bagged and weighed down with lead bricks to ensure it does not float to the surface and give away the ship’s position.

TERMINAL VELOCITY A falling or accelerating object in a fluid (air or water) eventually stops speeding up when fluid drag balances accelerating force. The velocity that is reached is called terminal velocity.

TEST DEPTH A depth about 2/3 of crush depth. Maximum allowed depth a submarine is allowed to go in peacetime.

TG’S (TURBINE GENERATORS) The two turbines aft that turn the ship’s electrical generators and provide electrical power.

THERMAL LAYER A layer of warm water near the surface of the ocean. The water is warm because of agitation by waves and sunlight. Further down, the wave motion is nil and there is no sunlight, leaving the seawater near freezing at all times. Sound waves originating below the layer bounce off it and come back down, making it difficult for surface ships to detect deep submarines, and the reason surface ships use dipping sonars or deep towed arrays. Sound waves originating above the layer will bounce off the layer and come back up, making surface ships difficult for submarines to hear when approaching the surface to come to periscope depth. Sometimes the layer confines surface noise into sound channels, enabling a submarine to hear a contact above the layer hundreds of miles away. Layer depth is typically 150 to 200 feet deep.

THERMAL NEUTRONS Neutrons slowed by water moderator in a reactor core, enabling them to be absorbed by another uranium nucleus to cause fission.

THERMAL STRESS Stress in metal caused by one side being hot and the other being cold. The hot part wants to expand, the cold part wants to contract, and the result is the metal trying to tear itself apart. An example is a rapid heatup of the massive metal of a reactor pressure vessel when raising plant water temperature after a scram. The inside surface of the vessel can be 500 degrees, while the outside and the “meat” of the thick metal is still at 300 degrees. The vessel can rupture, causing a loss-of-coolant accident. Neutron embrittlement of the vessel makes thermal stress effects even worse.

THERMOLUMINESCENT DOSIMETER (TLD) A small piece of plastic worn on a crewmember’s belt to measure that person’s radiation dose.

THREE-WAY VALVE A valve, usually a ball valve, that can direct inlet flow one of two ways.

THROTTLE The valves at the inlet of a steam turbine that determine how much steam flow the turbine will receive, and thus, the amount of power the turbine will produce (and its speed). Done at the Steam Plant Control Panel.

THROTTLEMAN Nuclear trained enlisted watchstander who monitors the steam plant at the Steam Plant Control Panel and positions the throttle based on the speed orders of the control room (which are transmitted by the engine order telegraph).

TIME-BEARING PLOT A large graphical plot of target bearing versus time. Plot can be used to calculate contact range based on knowledge of own ship’s speed across the line-of-sight. Also used to call or verify a target zig when target bearing rate diverges from expected bearing rate.

TIME-FREQUENCY PLOT A large graphical plot of target tonal frequency versus time. Useful in zig detection, when a down shifted frequency shows the target moving away and an upshift shows the target turning toward own ship.

TITANIUM A special metal with high strength that is useful in submarine hulls due to its creep properties. Very expensive and almost impossible to weld.

TMA (TARGET MOTION ANALYSIS) Means of establishing a target solution using passive sonar. Own ship does maneuvers to generate speed first on one side of the line-of-sight, then on the other. Several maneuvers or legs can quickly find the target solution. Stealthy method of determining what the target is doing. The system is weak when the target is himself doing TMA. Result is a melee or PCO Waltz, where both submarines are maneuvering and neither knows what the other is doing. In worst case, submarines may need to shift to active sonar to determine range or clear datum until the target can be ambushed stealthily.

TONAL A steady sound frequency emitted by a target submarine. Usually very narrow bandwidth. Very much like the pure tone put out by a tuning fork. Caused by rotating machinery such as turbine generators.

TONAL SEARCH GATE A filter set up on a narrowband passive sonar that only listens to a small range of sound frequencies in anticipation of finding a particular tonal.

TOP SECRET Classification of information, the disclosure of which could “cause grave damage to the national security of the United States.” Detailed information regarding U.S. warplans and some U.S. OPS. Old submarine saying: confidential on the table, secret on the bed, top secret under the pillow.

TOP SECRET — THUNDERBOLT When the classification of top secret is followed by a codeword, it indicates the SCI classification, making the information classification essentially higher than top secret. Usually the very name of the classification is at least secret.

TOPSOUNDER A sonar transducer designed to transmit an active sonar beam upward to gauge the thickness of the ice cover overhead.

TORPEDO IN THE WATER Announcement that a hostile submarine has launched a weapon at own ship, requiring immediate evasive action and a counterfire.

TOWED ARRAY A passive sonar hydrophone array towed astern of a submarine on a cable up to several miles long. The array itself may be a thousand feet long. The array is used to detect narrowband tonals at extreme ranges.

TRACK To keep tabs on a contact’s solution over time. Merchant surface vessels are tracked to avoid collision. A casual maintenance of a fire-control solution to a contact.

TRAIL The serious prosecution of a target intended to maintain weapons ready to fire at the target at all times while remaining undetected. The constant maintenance of an accurate fire-control solution to an enemy submarine. Trail ranges vary from 10,000 yards to 20 yards. The trick is to keep from being counterdetected, which can be embarrassing. U.S. attack submarines will keep Russian boomers in trail as much as possible to ensure they can be sunk if they get ready to fire ballistic missiles. Second priority for trailing is a Russian attack sub. Third priority is another U.S. unit, to see if they can be trailed without their knowledge. Trailing a U.S. unit is extremely difficult unless they are making transient noises or have broken equipment.

TRANSCEIVER Refers to radio equipment or sonar equipment that can both receive and transmit.

TRANSDUCER A sonar hydrophone that can ping active sonar pulses and listen and analyze the returning pulses.

TRANSIENT A noise that is made by an enemy sub due to a temporary condition. Examples include dropped wrenches, boots clomping on deckplates, slamming hatches, boiler blowdowns, rattling check valves, etc.

TRIM The balance of a submarine. The first step is to pump or flood variable ballast to achieve neutral buoyancy. The second is to pump from tank to tank to balance the ship fore and aft and port to starboard.

TRIM PUMP A large pump that can pump variable ballast from tank to tank or from a tank to the sea to achieve a good trim. Can be connected to the drain system for use as a backup for the drain pump.

TRIM SYSTEM The piping network, tanks, and trim pump used to establish a good trim. Can be cross-connected to the drain system as a backup for the drain pump.

TRIP The actuation of an interlock, such as a reactor scram.

TURBINE A mechanical rotating device with blades that converts the pressure energy, velocity energy, and internal (temperature) energy of a fluid stream (steam or combustion gases) into mechanical power.

TWO THIRDS SPEED An engine order between All Ahead One Third and All Ahead Standard. Gives approximately 10 knots.

TWO-MAN CONTROL Term referring to the handling of authenticators for nuclear release message validation. No one man is ever alone with an authenticator. The authenticators are locked in double safes, and no one man has the combination to both.

TYPE 18 PERISCOPE Modem periscope able to act as a means of seeing outside the ship at PD, but also is able to receive radio messages from the satellite and allow reception and analysis of incoming radar signals. Contains video camera and low-light capability as well as a still photograph camera.

T-AVE (AVERAGE REACTOR COOLANT TEMPERATURE) An estimate of in-core water temperature by electrically averaging the outlet high temperature water (T-Hot) and the inlet low temperature water (T-Cold).

T-HOT Hot leg temperature, the temperature of water leaving the reactor core. Usually about 520 to 560 degrees IF.

T-HOT CUTBACK A cutback inserted when T-HOT gets above a trip setpoint.

T.O.T. (TIME-ON-TARGET) A land attack assault in which weapons are launched at carefully planned moments to cause all weapons to detonate on target at the same instant in time.

More remote launching platforms must fire before closer units.

ULTRAQUIET Ship systems lineup done in a tactical situation such as a close trailing OP or in wartime. Only the quietest equipment is running. Offwatch personnel are required to be in bed. The galley, showers, laundry, movies, and maintenance of equipment are all prohibited to minimize noise. Hard-soled shoes are prohibited. Lights are shifted to red to remind the crew of the need for silence.

UNDERHULL An operation in which a submarine sneaks up to a target when the target is in a surface transit or is running shallow. The submarine doing the underhull raises the periscope, starts the video recorder, and drives around the target taking video pictures of the ship’s hull. Especially valuable when done on a new ship, since the pictures are better than if a cameraman were sent into the ship’s drydock. Extremely dangerous operation.

UNIFORM WHISKEY MIKE Code for “your weapon missed me.”

UNIT A torpedo launched by own ship. As opposed to a torpedo (after sonar calls “torpedo in the water”), which is launched by a hostile submarine.

UWT (UNDERWATER TELEPHONE) A sonar system using voice transmissions instead of tones or pulses, used for communication between two submarines that are fairly close.

VACAPES OPAREA Virginia Capes Operation Area. A region off the continental shelf east of Norfolk where submarines of the Norfolk base practice tactics.

VALVE-OP WATER FLASKS (VOWF) Tanks of pure water used for hydraulically operating nuclear system valves. Can also be used to charge to the primary coolant system by air loading with high pressure air.

VARIABLE BALLAST TANKS Tanks used to hold seawater for added weight, or conversely, seawater tanks that can be pumped out or blown out to lighten the ship.

VARIABLE YIELD Yield is a nuclear warhead’s explosive power in kilotons or megatons. A warhead with variable yield can dial in the desired explosive power by changing the shape or size of the implosion charges or by altering the geometry or concentration of the fissionable (or fusion) material.

VECTOR Any quantity that has both magnitude and direction. Example: a velocity vector is speed (number of miles per hour) and direction (north).

VENT To release trapped air from a system.

VERTICAL SURFACE When a hovering submarine blows water from a variable ballast tank to establish a vertical velocity and then rises vertically from the water. Generally only used to surface through the ice.

VICTOR A class of Russian attack submarines built to counter the threat from the Piranha class of submarines.

VICTOR III A class of Russian attack submarines that are much more refined, quieter, and faster than the VICTOR class (only a few VICTOR II’s were built, and may be considered experimental models of the VICTOR Ill’s). Built to counter the Los Angeles class submarines. Precursors to the AKULA class attack submarines.

VITAL BUS A group of electrical loads supplied off the same motor generator breaker, able to be fed either from a turbine generator or the battery. These few loads are vital to the survival of the ship. Examples include primary ship control circuits, slow speed reactor main coolant pumps, reactor protection circuitry, and the wardroom coffee maker.

VLF LOOP An antenna capable of receiving VLF transmissions at depths down to several hundred feet.

VLF (VERY LOW FREQUENCY) Radio transmissions on a longer wavelength than LF but not as long as ELF.

VLS (VERTICAL LAUNCH SYSTEM) New missile launch system on later Los Angeles class attack submarines, in which space in the forward group of ballast tanks has vertical torpedo tubes for launching Javelin cruise missiles. Allows torpedo room space to hold more torpedoes.

WARDROOM (1) Officers’ messroom. Used also as a conference room, briefing room, reconstruction room, junior officers’ office, movie screening room, and place to converse. (2) The group of officers assigned to a ship.

WARSHOT A weapon that is used to sink an enemy ship or inflict damage on a target. As opposed to an exercise shot.

WATCH/WATCHSTATION A watch is an 8-hour shift during which a group of men at specific stations run the submarine. A watchstation is a person’s station or assignment during the watch.

WATCHSECTION A collection of watchstanders who run the submarine for an 8-hour shift called a watch.

WATER SLUG Shooting a torpedo tube when it is only full of water. A “slug” of water is ejected from the tube.

WATERFALL A display of broadband sonar with bearing on the horizontal and time on the vertical. Broadband noise traces fall down the screen, looking like a waterfall.

WIGGLE RANGE TMA range obtained by the wiggling of an advanced sonar system’s towed array hydrophones due to the tow cable moving in the water flowstream. Each hydrophone has accelerometers and instrumentation to determine its position and motion with respect to the contact and own ship.

WIRE GUIDE CONTINUITY A low electrical resistance in the wire guide to a torpedo, indicating the wire is still intact. Loss of wire guide continuity means the weapon got fouled in the wire and cut it, or that the weapon has exploded.

XO (EXECUTIVE OFFICER) Officer who is second in command of a nuclear submarine, responsible to the captain for the administrative functioning of the ship. At battle stations, the XO coordinates the fire-control team and makes recommendations to the captain.

ZIG A term used to describe a target’s maneuver, either a turn, speed change, or both.

ZIRCONIUM A metal used as cladding on uranium fuel elements because of its corrosion resistance and low neutron absorption characteristics.

ZULU Same as Greenwich Mean Time.