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 (EL
ECTRONICS 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 s
atellite 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.
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