Submarine: A Guided Tour Inside a Nuclear Warship

Glossary

1MC Main shipwide announcing circuit on U.S. submarines.

ADCAP ADvanced CAPability. Newest version of the Mark 48 torpedo on board U.S. submarines.

AFFF Aqueous Fire Fighting Foam.

Akula SSN A third-generation Russian design competing with the Sierra I and II classes, the Akula appears to be the overall winner. This boat is very quiet, equivalent to a U.S. Flight I 688, and is equipped with acoustic and nonacoustic sensors. Largest SSN class in production. How large the class size will be is unknown, but at present there are seven Akulas in the Russian inventory.

AN/BPS-15A Navigation radar on many U.S. SSNs.

AN/BQQ-5 (A-E) Integrated sonar suite on most U.S. SSNs. The different variants include improvements in signal process and/or different sonar arrays.

AN/BSY-1 Integrated sonar and fire control system on Improved Los Angeles-class SSNs.

AN/WLR-8(V)2 Radar warning receiver on 688I-class SSNs.

AN/WLR-9 Acoustic intercept receiver found on U.S. Navy submarines.

AN/WLR-10 Radar warning receiver with recording capability on 688-class SSNs.

Anechoic coating Rubber coating applied to the exterior hull surfaces of a submarine to absorb active sonar pulses. Reduces the detectability by active sonars. Some coatings also reduce the amount of noise a submarine puts into the water; these are called decoupling coatings.

Angles and dangles Test conducted by a submarine to ensure that everything is stowed properly before beginning its mission. The procedure calls for making large up-and-down movements with the submarine as well as using large rudder angles at moderate speeds.

ASDIC Allied Submarine Detection Investigation Committee. Formed during World War I (1914-18) to conduct research and experiments on submarine detection.

ASW AntiSubmarine Warfare.

AUTEC Atlantic Undersea Test and Evaluation Center. An acoustic test range located off Andros Island in the Bahamas.

Bastions Highly defended SSBN patrol areas. Established by the former Soviet Union, now used by Russia to protect their SSBNs from attack by Western SSNs.

Blue/gold crew The policy of having two alternating crews aboard strategic missile submarines.

BOL (Bearing Only Launch) Launch mode for Harpoon and Tomahawk antiship missiles that doesn't require range information. Essentially the missile seeker is activated once cruising altitude is reached.

Bomb shop Royal Navy term for the torpedo room on submarines.

Bombers Royal Navy nickname for strategic missile submarines.

Boomers U.S. Navy nickname for strategic missile submarines.

Bottom bounce Term used to describe the route taken by sound waves as they bounce off the ocean bottom traveling from the noise source to the sonar receiver. For example, the noise source could be an active sonar pulse that bounces off the bottom and hits the target ship; then the echo bounces off the bottom again and is received by the sonar.

Breech door Inner door of a torpedo tube.

Bridge Small observation area on top of the fairwater. The OOD stands his watch here when the submarine is on the surface.

Buttercup U.S. Navy term for the "wet" or flooding trainer.

Cavitation The formation of tiny vapor (air) bubbles on the surface of a propeller when the propeller moves through the water rapidly. Cavitation is a source of very loud noise.

CENTCOM U.S. CENTral COMmand.

CH 084 Multifunction attack periscope on Royal Navy SSNs.

Choke point Geographical restriction that limits the maneuverability of a ship or submarine.

CIS Commonwealth of Independent States (formerly the Soviet Union).

CK 034 Multifunction search periscope on Royal Navy SSNs.

Clyde U.S. Navy nickname for the auxiliary diesel engine.

CO Commanding Officer. Title given to an officer in command of a ship. Often called "Captain" or "Skipper."

COB Chief of the Boat. Senior enlisted man in the submarine's crew. Usually a senior or master chief petty officer. Interfaces directly with the XO on issues that affect the enlisted personnel. The Royal Navy equivalent is the coxswain.

COMINT COMmunications INTelligence.

COMSUBLANT COMmander, SUBmarine Force AtLANTic.

COMSUBPAC COMmander, SUBmarine Force PACific.

Conform Name of a Navsea-designed SSN in competition with Admiral Rickover's 688 design.

Control room Area on a U.S. Navy submarine where the submarine's ship control, fire control, and periscopes are located. All major submarine functions are controlled from this location. The OOD stands his watch here when the submarine is submerged. In communications the area is referred to as the conn.

Convergence Zone (CZ) Phenomenon whereby, if the water is deep enough, water pressure turns sound waves up toward the surface. This occurs at intervals of roughly 30 nautical miles. Multiple CZ contacts are possible when the sound bounces off the surface and heads back down, eventually to be turned back upward again by the pressure.

COW Chief of the Watch. Leading enlisted man in control during a watch. Operates the ballast control panel to dive and surface the submarine and makes trim corrections when directed by the diving officer.

CVBG Aircraft Carrier Battle Group.

Delta I to IV SSBNs The Russian Delta series of SSBNs is an ongoing variant of the basic Yankee-class SSBN design. Almost all variations are determined by the type of SLBM being carried. The latest variant, the Delta IV, also incorporates quieting and sensor enhancements. A total of forty-three Deltas have been built.

Direct path Term used to describe the route that sound waves take from noise source to sonar system without interacting with the surface or the ocean floor. Roughly speaking, it is considered to be the straight-line distance between the two vessels.

DNR Director, Naval Reactors

Dolphins Symbol of the submarine force in just about every nation. Also, the badge or pin that designates a sailor as qualified in submarines.

Dreadnought (S-98) First Royal Navy SSN. Essentially a U.S. Skipjack-class back end mated to a Royal Navy front end.

DSMAC Digital Scene-Matching Area Correlation. A second Tomahawk land attack missile navigation system used to improve the accuracy of the conventional variants. Uses a cameralike system to make detailed digital pictures of the terrain and compares them with stored images in the guidance computer.

DSRV Deep-Submergence Rescue Vehicle. A small rescue submersible designed to dock with a sunken submarine and retrieve the crew.

EAB Emergency Air Breathing system. A low-pressure air system that crewmen can plug in to and obtain breathable-although dry-air. This system is to provide a source of air while a submarine ventilates to get rid of the smoke from a fire.

Echo SSN A first-generation Soviet nuclear-powered submarine, it originally was designed as an SSGN (Echo I class), but the tubes were removed and the units converted to SSNs. These submarines were noisy and had extremely unsafe radiation problems. All have been retired because of their poor safety record. A total of six units were built.

Electric Boat Company The company started by John Holland to produce submarines for the U.S. Navy. Presently owned by General Dynamics Corporation.

ELF Extremely Low Frequency radio band.

Emergency blow Process by which high-pressure air is rapidly introduced directly into the submarine's main ballast tanks. An emergency blow makes the submarine positively buoyant, and it will rise to the surface quite quickly. This system was instituted as part of the Subsafe program following the loss of the USS Thresher.

Enigma World War II German communication cipher (encryption) system.

EOOW Engineering Officer of the Watch. Officer in charge of the team that is monitoring and manipulating the submarine's reactor and propulsion system. Key responsibility is to maintain propulsion in a safe manner.

ESM Electronic Support Measures. A passive receiver system designed to detect radar emissions from aircraft and surface ships.

Ethan Allen (SSBN 608) First U.S. Navy SSBN class designed to carry Polaris missiles. Larger than the George Washington class, the Ethan Allen class has more quieting measures to improve stealth. A total of five units were built.

Exocet Antiship cruise missile made by the French firm Aerospatiale. Slightly smaller than a Harpoon but just as deadly.

Fairwater U.S. Navy term for the sail on a submarine. The Royal Navy uses the term Fin.

Familygrams Short (forty to fifty words) messages that U.S. Navy submariners receive from family members about once a week while on patrol.

FBM Fleet Ballistic Missile submarine.

First lieutenant The Royal Navy equivalent of a U.S. Navy executive officer. Often referred to as "Number One."

"Flaming datum" A ship that has been hit by a torpedo fired from a submarine. It is the place to begin searching for a submarine, because one is known to be in the area.

George Washington (SSBN-598) First U.S. Navy SSBN class. Essentially Skipjack-class SSNs with a hull insert containing sixteen missile tubes for Polaris missiles. A total of five units were built.

Gertrude Old WW II phrase used to describe any equipment whose function is underwater communications.

Glenard P. Lipscomb (SSN-685) One-of-a-kind experimental U.S. submarine, basically a Sturgeon-class hull with a second-generation turboelectric drive. Fully combat capable.

Goat locker U.S. Navy term for the chief's quarters on a submarine.

GPS Global Positioning System. A constellation of Navstar satellites that can very accurately determine the submarine's location.

Halibut (SSN-587) Originally designed as an SSGN carrying Regulus land attack missiles, she was reconfigured as an SSN when the Polaris program proved to be successful.

Harpoon (UGM-84) U.S. Navy antiship missile, fired from an SSN's torpedo tube.

HE High Explosive.

Head U.S. Navy term for a washroom and toilet.

HF High Frequency.

HMS Dolphin Royal Navy Submarine School.

Holland (SS-1) First U.S. Navy submarine, designed and built by John Holland.

Hot bunking Rotation system whereby two men share a single bunk. While one man is on watch the other is sleeping. When it is time for watch rotation the man coming off watch climbs into a bunk that was just recently vacated and is usually still warm.

Hotel II & III SSBN First-generation Soviet SSBN. These submarines were noisy and extremely unsafe from a radiological standpoint. All have been retired because of their poor safety record and to meet SALT SSBN tube limitations. The Hotel III SSBN was a trial submarine for the SS-N-8 Sawfly SLBM. Approximately nine units were built.

Hunley A Confederate Navy vessel that made history by being the first submarine to sink a surface ship in battle (USS Housatonic). Unfortunately, the Hunley herself also sank in the attack.

HY-80 High-Yield steel, with a yield strength of 80,000 pounds per square inch.

HY-100 High-Yield steel, with a yield strength of 100,000 pounds per square inch.

Kilo SS Latest Russian diesel-electric submarine. The Kilo is a medium-range coastal defense submarine that is being offered on the export market. Using state-of-the-art Russian sensors and torpedoes, the Kilo class compares favorably against older Western designs. Russia has twenty Kilos in their naval order of battle, and approximately fourteen have been sold to various countries.

Lafayette (SSBN-616) Third generation of U.S. Navy SSBNs. Larger and quieter than the Ethan Allen class, the Lafayette class carries the Poseidon C-3 missile. However, twelve units of the Lafayette class were backfitted with the Trident I C-4 system during the 1980s. A total of thirty-one units were built.

LF Low Frequency.

LOFAR LOw-Frequency Analyzing and Recording. Term used to describe the process by which narrowband "tonals" are displayed on a modern sonar system.

Los Angeles (SSN-688) Admiral Rickover's high-speed submarine design. Most numerous submarine class in the world with a total of sixty-two units to be built. There are three flights with various improvements:* Flight 1: SSNs 688–718. Basic Los Angeles class.* Flight 2: SSNs 719–750. VLS, more powerful reactor core.* Flight 3: SSNs 751–773. AN/BSY-1, bow planes, improved quieting, under-ice capability.

Maneuvering The reactor and propulsion control area located in the engine room. The EOOW stands his watch here.

MEO Marine Engineering Officer. Royal Navy equivalent of the chief engineer; however, an MEO is not eligible for command.

MF Medium Frequency.

MGU Midcourse Guidance Unit. The inertial navigation system used to guide Harpoon and Tomahawk antiship missiles to their targets.

MIDAS MIne Detection and Avoidance Sonar. New mine-hunting sonar on Improved Los Angeles-class SSNs.

Mk 8 (Mark 8) WW II-era straight-running (nonhoming) torpedo used by the Royal Navy up until about the mid-1980s. Two Mk 8s were responsible for the sinking of the Argentinean light cruiser General Belgrano.

Mk 48 (Mods 1–4) Designation of the active homing torpedo used by U.S. SSNs. The various modifications have improvements in wire-guidance capability and allow for deeper depths.

Mk 57 U.S. Navy moored influence mine.

Mk 6 °Captor EnCAPsulated TORpedo mine. A deep-water moored acoustic influence mine containing a Mark 46 lightweight torpedo as the payload.

Mk 67 SLMM Submarine-Launched Mobile Mine. An obsolete Mk 37 electric torpedo that has been converted into a mobile bottom influence mine.

Narwhal (SSN-671) Basic Sturgeon-class hull with a natural circulation reactor. One-of-a-kind experimental submarine. Fully combat capable.

NATO North Atlantic Treaty Organization

Nautilus (SSN-571) First nuclear-powered submarine in the world. Commissioned September 30, 1954.

Navsea Naval Sea Systems Command.

NIFTI Navy InFrared Thermal Imager.

November SSN First-generation Soviet SSN. Fast, noisy, and extremely unsafe because of radiation. These SSNs have all been retired because of their poor safety record. A total of fourteen were built. One was lost off Cape Finisterre in April 1970.

OBA Oxygen Breathing Apparatus. A portable system that chemically generates oxygen for about 30 minutes. Used by damage control teams to fight fires.

Ohio (SSBN-726) Fourth generation of U.S. Navy SSBNs. Largest submarines in the fleet; each carries twenty-four Trident I C-4 or Trident II D-5 missiles. Extremely quiet submarines. Essentially 688s with twenty-four missile tubes. A total of twenty were to be built, but because of START and the collapse of the USSR only eighteen units will be completed.

OOD Officer Of the Deck. U.S. Navy officer in charge of directing the submarine's movement and ensuring that essential actions are conducted. Primary responsibility is to keep the submarine out of dangerous situations and to keep the captain informed.

OPNAV Office of the Chief of NAVal OPerations.

ORSE Operational Reactor Safeguards Examination.

Oscar I & II SSGN Third-generation Soviet SSGN, the Oscar is the largest attack submarine ever built. Fast, quiet, and extremely well armed, the Oscar I & II classes are a threat to any surface ship. To date nine units have been built, and production appears to be continuing.

Otto Fuel The monopropellant (oxidizer and fuel combined) used in Mk 48 and Spearfish torpedoes.

Perisher Royal Navy Submarine Command Course.

Permit (SSN-594) First U.S. Navy production SSN with a primary ASW function. Class was renamed following the loss of USS Thresher in April 1963. Fourteen units of this class were eventually built.

Plank owners The original crew of a boat at the time of its commissioning.

Polaris (A1-A3) First generation of U.S. Navy submarine-launched ballistic missiles. The different variants each have improvements in range. The Royal Navy uses Polaris A-3 missiles in their Resolution-class SSBNs.

"Polishing the cannonball" An attempt to generate a near-perfect fire control solution that may be totally unnecessary. Polishing the cannonball takes too much time, and the submarine may lose its initiative to the intended target.

Poseidon (C-3) Second-generation U.S. Navy submarine-launched ballistic missile.

PSA Post Shakedown Availability. Maintenance period after a new submarine's initial sea trials are completed.

PWR-1 Pressurized Water Reactor-1. The type of reactor found on all current Royal Navy nuclear-powered submarines except the Vanguard-class SSBNs. PWR-1 is essentially the U.S. S5W reactor design, which was sold to the Royal Navy in 1958.

PWR-2 Pressurized Water Reactor-2. An indigenous reactor design for future Royal Navy nuclear-powered submarines. Presently being installed in the new Vanguard-class SSBNs.

Radar RAdio Detection And Ranging.

Raft A large metal frame that supports various rotating parts of machinery such as main engines or turbine generators. Through inertial damping it reduces machinery vibrations that could reach the hull.

In other words, it's heavy, and the vibrations are absorbed as they try to move the raft.

RAM Radar-Absorbing Material. A coating designed to absorb radar energy and reduce a target's ability to be detected.

RBL–L Range Bearing Launch-Large. A launch mode of Harpoon and Tomahawk antiship missiles that uses both bearing and range information. The "Large" refers to the size of the area where the missile is to conduct its search.

RBL-S Range Bearing Launch-Small. A launch mode of Harpoon and Tomahawk antiship missiles that uses both bearing and range information. The "Small" refers to the size of the area where the missile is to conduct its search.

Resolution (S-22) First Royal Navy SSBN. Very similar to the U.S. Lafayette-class SSBN, the Resolution class carries sixteen U.S. Polaris A-3 missiles armed with British reentry vehicles. A total of four units were built.

RNSH Royal Navy Sub Harpoon.

RORSAT Russian Radar Ocean Reconnaissance SATellite.

S6G The designation of the pressurized water reactor installed in 688-class SSNs.

SAM Surface-to-Air Missile.

SBS Special Boat Service. The Royal Navy equivalent of the U.S. Navy SEALs.

Scorpion (SSN-589) Second U.S. Navy SSN (Skipjack class) to be lost at sea, sometime in May 1968. Most likely cause appears to be an explosion.

SCRAM Safety Control Reactor Axe Man. Term given to the man at the University of Chicago, where the first nuclear core was tested, who was responsible for cutting the rope holding the control rods should something go wrong. The method of inserting control rods has changed considerably, but the term has been retained. With a rapid insertion of control rods the reactor will be made subcritical and will no longer support a sustained nuclear fission reaction.

SEAL SEa-Air-Land. U.S. Navy special forces/commando units.

Seawolf Second U.S. Navy SSN (SSN 575). It is also the class name for the new SSN 21 submarine presently under construction at Electric Boat Company in Groton, Connecticut.

SHF Super High Frequency.

SHP Shaft HorsePower.

Shutter door The outer door of a torpedo tube.

Sierra I & II SSN Third generation of Soviet SSNs. The Sierras are quiet, deep-diving submarines. The pressure hull is made of titanium, which makes Sierra expensive to build. This is reflected in the fact that only four have been built to date. The shipyard that produces Sierras is reportedly going out of the submarine construction business, so four units may be the total class size.

Signal ejector A small (usually 3-inch) torpedo tube-like system for launching flares, noisemakers, and torpedo decoys.

SINS Ship's Inertial Navigation System. A set of gyroscopes that monitor the submarine's position from an established reference point in space.

Skate (SSN-578) First U.S. Navy production SSN class; four units total.

Skipjack (SSN-585) First U.S. Navy SSN class to use the teardrop hull shape. Fastest SSN in the fleet until the Los Angeles class. Total of six units built.

SLBM Submarine-Launched Ballistic Missile.

SLOT Submarine-Launched One-Way Transmitter.

SNAPS Smith Navigation And Plotting System. The navigation and plotting tables used on Royal Navy ships and submarines.

Snapshot Term used to describe the procedure for launching a torpedo in an emergency situation. In a snapshot the submarine crew doesn't have time to conduct TMA but simply shoots a torpedo down the bearing of an incoming weapon or a close contact. Rapid reaction is the basis of the snapshot mode.

SOAC U.S. Navy Submarine Officers Advanced Course.

SOBC U.S. Navy Submarine Officers Basic Course.

Sonar SOund Navigation And Ranging.

SOSUS SOund SUrveillance System. A series of fixed passive sonar arrays used by NATO to provide early warning of deployments into the open ocean of former Soviet submarines.

Sound isolation mount Springlike mount that absorbs machinery vibration by being stretched and relaxed. The vibration energy needed to move the mount doesn't reach the hull and therefore can't be transmitted into the ocean. These mounts are usually made of metal and rubber, although the Royal Navy prefers a polymer-type spring mount.

Spearfish Royal Navy's torpedo equivalent to the Mk 48 ADCAP. Although noisier than the Tigerfish, the Spearfish is faster, with greater endurance and improved homing logic.

SRA Short Range Attack. A mode of firing the Mk 48 torpedo to accommodate a target that is very close to the attacking ship.

SS Diesel-electric attack submarine.

SSBN Strategic ballistic missile submarine, nuclear powered.

SSGN Nuclear-guided (cruise) missile submarine.

SSM Surface-to-Surface Missile. Also used in reference to antiship cruise missiles.

SSN Attack submarine, nuclear powered.

SSK Diesel-electric submarine, hunter-killer.

SS-N-9 Siren Antiship cruise missile on Russian Charlie II-class SSGNs. Range is about 60 nautical miles.

SS-N-14 Silex Russian ASW missile that deploys a torpedo or nuclear depth bomb. Its range is about 30 nautical miles.

SS-N-18 Stingray Submarine-launched ballistic missile on Russian Delta III SSBNs.

SS-N-19 Shipwreck Antiship cruise missile on Russian Oscar-class SSGNs. Range is about 300 nautical miles.

SS-N-20 Sturgeon Submarine-launched ballistic missile on Russian Typhoon SSBNs.

SS-N-23 Skiff Submarine-launched ballistic missile on Russian Delta IV SSBNs.

START STrategic Arms Reduction Treaty.

Steinke hood Combination breathing device and life preserver used during free ascents from a sunken U.S. submarine.

Sturgeon (SSN-637) Follow-on to the U.S. Permit class. The Sturgeon class is a little larger and incorporates additional quieting measures. A total of thirty-seven units built.

SUBGRU SUBmarine GRoUp.

SUBROC SUBmarine ROCket. A submarine-launched ballistic rocket with a nuclear depth bomb payload.

SUBRON U.S. SUBmarine SquadRON.

Subsafe Procedural and system changes instituted to increase the safety of U.S. submarines following the loss of the USS Thresher (SSN- 593) in April 1963.

SURTASS SURveillance Towed Array Sensor System (AN/UQQ-2). Essentially a mobile SOSUS array towed by small Ocean Surveillance Ships (T-AGOS).

Swiftsure (S-104) Third generation of Royal Navy SSNs. Improved quieting and sensors over the Valiant class. In the redesigned location of the main conformal array the Swiftsures lost a torpedo tube (five instead of six). A total of six units were built.

TASO Torpedo and Anti-Submarine warfare Officer. Royal Navy term for the junior seaman officer in charge of the submarine's torpedo launching system.

TB-16 (A-D) Standard U.S. Navy SSN "fat line" towed array. The various modifications (mods) allow the submarine to search at higher speeds without degrading performance. The array is stored in a sheath that runs along the hull.

TB-23 First U.S. Navy "thin line" array found on SSNs equipped with AN/BSY-1 and AN/BQQ-5E. This array is about four times longer than the TB-16 series and is stored entirely on a reel located in the aft ballast tank area.

TDU Trash Disposal Unit. A tube that ejects weighted trash cylinders from the bottom of a U.S. submarine.

Tea kettle Royal Navy term for the reactor on nuclear-powered submarines.

TERCOM TERrain-COntour Matching. A navigation system on Tomahawk land attack missiles. The system uses the Tomahawk's radar altimeter to make terrain profiles at preselected points along the missile's route. These profiles are compared to a radar reference map to determine if flight corrections are needed.

TEZ Total Exclusion Zone.

Thresher (SSN-593) Lost April 4, 1963, during deep-diving trials following an overhaul period. The loss caused the U.S. Navy to institute the Subsafe program.

Tigerfish (Mk 24, Mods 0–3) A quiet, electric-powered dual-purpose torpedo in service with the Royal Navy.

TMA Target Motion Analysis. The process by which computers or men determine a target's course, speed, and range so that a torpedo or missile can be fired accurately.

TMPS Theater Mission Planning System. U.S. TMPS centers plan Tomahawk land attack mission routes to various targets around the globe using maps and navigation information provided by the Defense Mapping Agency.

Tomahawk (UGM-109) Family of cruise missiles that are launched from standard torpedo tubes or special vertical launch tubes on SSNs. The different variants are:* Tomahawk antiship missile (TASM)* Tomahawk land attack missile-nuclear (TLAM-N)* Tomahawk land attack missile-conventional, HE warhead (TLAM-C)* Tomahawk land attack missile-conventional, bomblets (TLAM-D)

Torpedo The self-propelled torpedo was invented by Robert White-head, an Englishman, in 1866. Since then, the torpedo has undergone significant improvements in speed, range, and depth. Present-day torpedoes are all homing weapons using either active/passive acoustics or wake sensors.

Towed array String of passive hydrophones towed at some distance behind the ship. By separating the hydrophones from the ship, the array was no longer limited by platform noise, thereby increasing detection range. The towed array can also be made as long as necessary to detect sounds with long wavelengths (very low frequency).

Trafalgar (S-107) Fourth-generation Royal Navy SSN. Basically a slightly larger Swiftsure to accommodate additional quieting measures. Production has just ended, with a total of seven units being built. A modified Trafalgar design, called Trafalgar Batch II, is being worked on with the cancellation of the SSN 20 ("W" class).

Trident I (C-4) Third generation of U.S. Navy submarine-launched ballistic missiles.

Trident II (D-5) Fourth generation of U.S. Navy submarine-launched ballistic missiles.

Triton (SSN-586) Only U.S. Navy SSN built with two nuclear reactors. Originally designed as a radar picket submarine, Triton made a submerged round-the-world cruise in 1960.

TSO Tactical Systems Officer. Royal Navy term for the junior seaman officer in charge of the submarine's fire control system.

Tullibee (SSN-597) First U.S. Navy SSN with torpedo tubes placed amidships to make room for the large 15-foot spherical sonar array. This design is the basis for all later U.S. SSN designs. Tullibee was also fitted with a troublesome turboelectric drive, which earned her the reputation of being a hangar queen, and she was often referred to as "Building 597."

Turtle A semisubmersible craft designed and built by David Bushnell during the American Revolutionary War. It was the first submarine to conduct an attack, albeit unsuccessful, against a hostile surface ship (HMS Eagle).

Type 18 A multifunction search periscope found on U.S. SSNs.

Type 2 An optics-only attack scope, reminiscent of WW II periscopes, on U.S. submarines.

Type 2019 Acoustic intercept receiver on Royal Navy submarines.

Type 2020 Active/passive conformal array on Royal Navy SSNs.

Type 2027 A computer processor hooked to the Type 2020 to determine range based on multiple arrival paths of a target's noise. Multipath ranging.

Type 2046 Royal Navy towed array for submarines. This clip-on array is attached to one of the stern planes.

Type 2072 A new flank array for Royal Navy SSNs, to replace the older Type 2007.

Typhoon SSBN The size of a small WW II battle cruiser, the Typhoon is the largest submarine ever built. Very quiet, and equipped with modern sensors. A total of six units have been built.

U-boat Unterseeboot. The German name for submarines.

UAP ESM system on Royal Navy SSNs.

UHF Ultra High Frequency.

Ultra Allied special intelligence during World War II, obtained by the interception and decryption of German Enigma communications.

Upholder (S-40) Latest diesel-electric submarine in the Royal Navy. Intended to replace the aging Oberon class SS, the Upholders have been experiencing a number of teething pains including problems with their torpedo tubes. With the collapse of the Soviet Union, only four out of a projected class run of twelve units are to be built.

Valiant (S-102) Second-generation Royal Navy SSN. Based on the Dreadnought, the entire submarine was produced in the United Kingdom. A total of five units built.

Vanguard Second-generation Royal Navy SSBN. Twice as large as the Resolution class, the Vanguard class will carry sixteen U.S. Trident II (D-5) missiles. Described as being very quiet submarines. A total of four units are expected to be built.

VHF Very High Frequency.

Victor I & II SSNs Second-generation Soviet SSNs. Larger, quieter, and better equipped than November class. Victor IIs differ from Victor Is in that the Victor IIs have four 650mm torpedo tubes and are about 16 feet longer. A total of twenty-two units were built.

Victor III SSN A further modification of a second-generation design. The Victor III class is the first Soviet SSN that came close to Western standards in terms of quieting and sensors. The teardrop-shaped pod on the rudder is the housing for a towed sonar array. The Victor III is the most numerous class of SSN in the Russian inventory, with twenty-six units built.

VLF Very Low Frequency.

VLS Vertical Launch System. A set of twelve external tubes located in the number two main ballast tank on SSN 719 and on the Los Angeles-class SSN.

VSEL Vickers Shipbuilding Enterprises, Limited. The U.K. equivalent of Electric Boat Company.

Waterfall display Phrase used to describe the appearance that a modern passive sonar display makes while showing bearing versus time information. A contact will look like a bright line on a CRT against a speckled background of other noise sources.

WEO Weapon Engineering Officer. Royal Navy equivalent of the weapons officer; however, the WEO is not eligible for command.

XO Executive Officer. U.S. Navy term for the second in command of a ship.