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 Pa
nel 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 tra
iled 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).
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