Submarine, Nautical Terms and Glossary

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1MC The basic one-way communications system on a vessel. Reaches all spaces on a ship. Used for general announcements, and to transmit general alarm system signals. Control stations are located on the bridge, quarterdeck, and central station. Other transmitters may be installed at additional points. There are other MC and JV circuits used for communications within the ship. They are typically system-specific, i.e. weapons systems, navigation communication, engineering systems, firefighting, etc. See Announcing Systems.
0'dark thirty (or hundred) Pronounced "oh dark". Referring to some point really early in the morning. This term is typically used in mockery of Hollywood actors who pronounce military time with an "oh" rather than a "zero"--for example "oh-nine-hundred" as opposed to the correct military time: zero-nine-hundred (usually shortened to "zero-nine").
2JV Engineering sound-powered phone circuit. See sound powered phones.


Abaft  Aft of a given point on a ship; e.g. the bridge is abaft the bow.
Acey-Deucey  Backgammon, a board game traditionally played in off-duty hours.
Adrift Not secured; scattered about; not properly stowed, or out of place.
Aft To go towards the rear (stern) of a vessel. Used as a relationship term.
A-gang Auxiliaries Division of the Engineering Department. These personnel operate and maintain the ship's auxiliary equipment (air conditioning systems, distilling units, air compressors, etc.)
Alpha (1) First letter of the phonetic (sound) alphabet. Used when voicing the letter "A" to avoid confusion.

(2) A somewhat experimental class of Soviet submarine class of hunter/killer nuclear powered vessels. They were the fastest and deepest diving class of military submarines built. They were designed to meet the demanding requirements - sufficient speed to successfully pursue any ship; the ability to avoid anti-submarine weapons and to ensure success in underwater combat; low detectability, in particular to airborne MAD arrays, and also especially to active sonars; minimal displacement and minimal crew complement. A special titanium alloy hull would be used to create a small, low drag, 1,500 ton, six compartment vessel capable of very high speeds (in excess of 40 knots) and deep diving. The submarine would operate as an interceptor, staying in harbor or on patrol route and then racing out to reach an approaching fleet. A high-power liquid-metal-cooled nuclear plant was devised meaning extensive automation would also greatly reduce the needed crew numbers to just 16 highly trained men. The practical problems with the design quickly became apparent and in 1963 the design team was replaced and a less radical design was proposed, increasing all main dimensions and the vessel weight by 800 tons and almost tripling the crew.

(Soviet Alpha-class awaiting decommissioning.)

Alpha Particle In nuclear power, this is the heaviest sub-atomic particle -- and very ionizing -- but easily shielded by as little as a sheet of paper. Failed fuel cladding would be the primary source aboard ship and this would remain in the main coolant.
Acoustic Means "sound" as in acoustic (sound homing) torpedo.
After Battery Compartment (Diesel Submarine) Main section of the submarine behind the control room; houses battery cells and crew living and dining spaces. (see layout)

Alarms A submarine's alarm system is integrated into the 1MC System and consists of four signal generator modules, each one producing a specific sound.
  1. General Alarm - A gong sound, used for emergencies and battle stations. Duration: As long as necessary, about 6 seconds.
  2. Diving Alarm - A klaxon sound (See below for Diesel boats) - Used for diving and surfacing. Duration: Diving, sound two times then quit. Surfacing, sound three times then quit.
  3. Collision Alarm - A pulsing siren sound - Used for eminent collision warning. Duration: As long as necessary, about 7-10 seconds.
  4. Reactor or Power Plant Alarm - A pair of alternating high and low tones, similar to a European siren. Only on nuclear submarines. Duration: As long as necessary, about 7-10 seconds.

The Diesel submarines had electric, motor driven, klaxons dispersed throughout the boat. The modern signal is an approximate simulation. The general and collision alarms were generated by electronic modules.

For samples of the alarm sounds, click the words, below:

General Alarm

Diving Alarm (modern)

Surface Alarm (klaxon)

Collision Alarm

Reactor or Power Plant Alarm

AMR The Auxiliary Machinery Room. On some boats this space was also referred to as the AMS for Auxiliary Machinery Space. Fast attack submarines had one, FBM submarines had two, referred to as "Forward AMR(S)" and "Aft AMR(S)."
Announcing Systems

1MC — General Announcing - Used only as authorized by the Officer of the Deck.

Submarine General Announcing Groups:

1.     All - Ship wide

2.     Weather Deck Forward (Diesel boats)

3.     Weather Deck Aft (Diesel boats)

4.     Engine Rooms (Diesel boats)

5.     Upper & Main Deck Passages, Mess, Lounges, Galley (Diesel boats)

6.     Lower Deck Passageways, Shaft Alley, Steering Gear Room (Diesel boats)

2MC — Engineering Announcing - Propulsion Plant Engineering machinery spaces only

4MC — Damage Control 2-way Emergency Reporting Announcing used with the XJA system.

Various sound powered phone handsets throughout the ship have 4MC selectors.

When 4MC is selected the sound powered phone user can broadcast on the 4MC.

(see Intercom Systems)


Angles and Dangles (Submarine Service) Placing the boat in crazy angles and positions soon after leaving port, to see whether anything breaks loose. Similar-consequence noises while on patrol are not desired.
Angle of Attack The angle measured between the relative wind and the chord line of an airfoil. Essentially, the angle between the air movement (*not* the horizon!) and the aircraft’s wing. Has a tremendous import in the handling and behavior of the aircraft. Abbreviated AOA. Aka ‘Alpha’, from the engineering notation for AOA. Primarily an aviation term, although it is applicable to other fluid environments such as a ship’s propeller in water.

(Examples of the effect of changing angle of attack.)

Astern Something behind the stern (rear) of a vessel.
ASW Anti-Submarine Warfare.
AUX Pronounced ‘ox.’ Verbal shorthand for 'auxiliary', as when referring to a machinery space, 'Aux One'.
Auxiliaryman A member of the Auxiliary of “A” Gang. Typically they were non-nuclear trained Machinist Mates and Enginemen who maintained all of the non-nuclear mechanical systems on a nuke boat.
Aweigh (sometimes seen -- improperly -- as "away") When a ship raises (weighs) anchor, the anchor is said to be aweigh as soon as it is no longer in contact with the sea bottom. From the process of weighing anchor; the sequence of reports is usually as follows:

"Anchor’s at short stay" – The ship has been pulled up to the anchor, but the anchor is still lying on the bottom, undisturbed.

"Anchor’s up and down" – The anchor’s flukes have broken free of the bottom, and the shank is more or less vertical. The crown of the anchor is still resting on the bottom.

"Anchor’s aweigh" – The anchor has left the bottom. Legally, at this point the ship is under way, whether or not it is "making way" (moving through the water under its own power).

Aye, aye  "Yes (I heard the order, I understand the order, and I intend to obey the order)."




Baffles The cone-shaped area extending directly behind a submarine underway where sonar cannot detect any sounds due to the noise caused by the submarine’s own propeller.
Ballast Large tanks are filled with seawater, which acts as weight, causing the submarine to lose buoyancy and sink. To surface, compressed air is pumped into the tanks, forcing the seawater out and restoring positive buoyancy.
Batten Down Make fast, secure, or shut. Originally, deck hatches did not have hinged, attached covers. Hatch covers were separate pieces which were laid over the hatch opening, then made fast with battens (pieces of timber).
Belay (1) Stop. (2) Make fast. Derived from the practice of tying a line off (making it fast) using a belaying pin. (3) Disregard, as in "belay my last."
BCP The Ballast Control Panel. The watch station where everything pertaining to the trim of the boat can be monitored and controlled.
Beta Particle An electron of nuclear origin, its source is from the decay of fission products
Bilge "Bilge” is a nautical term which is used to refer to a several concepts. It dates from 1513, when “bilge” was first used to refer to the lowest compartment inside the hull of a ship, where the two sides meet at the bottom. However, the term is also used to discuss the matter which collects in the bilge: water drains from the decks of the ship into the bilge, dragging detritus from topside down below. The water that collects in the bilge is usually brackish and also has a foul odor, so bilge has also come to be a term which refers to anything foul or unpleasant. A bilge pump is a device which is used to remove water from the bilge.
Binnacle List Many novice sailors, confusing the words 'binnacle' and 'barnacle', have wondered what their illnesses had to do with crusty growths found on the hull of a ship. Their confusion is understandable. Binnacle is defined as the stand or housing for the ship's compass located on the bridge. The term binnacle list, in lieu of sick list, originated years ago when ship corpsmen used to place a list of sick on the binnacle health. After long practice, it came to be called binnacle list.
Bitter End Properly, the free or loose end of a line. Originally, the bitter end of a mooring line was taken to the bitts to secure it.
Black and Bitter, Blond..., Sweet.... The way a person takes their coffee. "Blond" indicates with cream, "sweet" indicates with sugar. Thus, a "blond and sweet" would be a coffee with cream and sugar while "black and bitter" would be without both.
Blivet  Traditionally, "Ten pounds of shit in a five-pound sack."
Blowdown A generic engineering term which can be used as noun or verb. A cleaning and/or venting process. Some specific applications: (1) A process for cleaning water-sides of a boiler. A top blow removes scum and floating contaminants, a bottom blow removes sludge. (2) To backflush and clean a SEACHEST. (3) The process of removing excess pressure from a system, or venting it completely.
Bluejacket's Manual The Bluejacket's Manual is the basic handbook for United States Navy personnel. First issued in 1902 to teach new recruits about naval procedures and life and offer a reference for active sailors, it has become the "bible" for Navy personnel, providing information about a wide range of Navy topics. The current version is the Centennial Edition, issued in 2002.




Bow The most forward part of a ship.
Boat Water craft small enough to be carried on a ship, unless a submarine, which is ALWAYS called a boat. A ship may be called a boat but ONLY by members of its crew, and only those who have actually completed a deployment.
Boomer Nuclear ballistic missile submarine. Primary mission is nuclear deterrence. Also used as a nickname for their crew members.
Bow Array That part of the sub’s sonar suite which is located in the bow.

(Diagram of the new Virginia-class area showing sonar bow array and mission-selectable missile tubes.)

Bridge On a submarine, the small observation area on top of the fairwater or sail.

(The bridge of a nuclear submarine.)

Bravo Second letter of the phonetic (sound) alphabet. Used when voicing the letter "B" to avoid confusion.
Bravo Zulu The term originates from the Allied Signals Book (ATP 1), which in the aggregate is for official use only. Signals are sent as letters and/or numbers, which have meanings by themselves sometimes or in certain combinations. A single table in ATP 1 is called "governing groups," that is, the entire signal that follows the governing group is to be performed according to the "governor." The letter "B" indicates this table, and the second letter (A through Z) gives more specific information. For example, "BA" might mean "You have permission to . . . (do whatever the rest of the flashing light, flag hoist or radio transmission says) "BZ" happens to be the last item in the governing groups table. It means "well done".
Brow The proper term for what is often called the ‘gangway,’ the temporary bridge connecting the ship’s quarterdeck to the pier.
Bubble The up or down angle of a submarine underway, measured in degrees from the horizontal. A “Zero Bubble” is an even keel.
Bug Juice A non-carbonated soft drink similar to Kool-Aid. This quickly becomes the "drink de jour" when fresh beverage supplies (i.e., milk) run out.
Bulkhead A wall or vertical partition.
Burner In a submarine, a system that burns carbon monoxide and hydrogen out of the air, converting H2 to water and CO to CO2. CO2 is then removed by the SCRUBBER.
Butt Kit Ashtray.




Captain's Mast Non-judicial disciplinary procedure, usually meted out by unit commanders.
Channel Fever Anxiety, usually registered while waiting to tie up to the pier after a long deployment.
Charlie Third letter of the phonetic (sound) alphabet. Used when voicing the letter "C" to avoid confusion.
Chicken Switches

Switches in the overhead above the Dive Officer's station that release 4,500 lb air into the main ballast tank, initiating the Emergency Main Ballast Tank blow (EMBT blow) causing the tanks to fill with air and the submarine to rise to the surface in a real hurry. Sometimes, engineering drills may cause the sub to go near test depth (depth the submarine has been tested to) if there is a delay in recovering the reactor (or many other reasons). So if the Dive Officer blows the tanks (actually, whoever has the Con will issue the order) they were afraid of sinking. Hence, Chicken Switches.

COB Only in submarines, this is the Chief of the Boat, the designated senior enlisted man aboard and serves as the senior enlisted advisor to the commanding officer and executive officer, and assists with matters regarding the good order and discipline of the crew. The Chief of the Boat is the equivalent of a Command Master Chief in shore and surface units. There is only one COB on a submarine and he is generally responsible for the day-to-day operations of the non-nuclear portion of the boat, and the morale and the training of the boat's enlisted personnel. The COB is typically the most senior enlisted man; however, the commanding officer is neither required to select the highest ranking sailor nor the most senior in grade or time aboard. Likewise, the COB is not necessarily replaced when a more senior sailor reports aboard.
Comb (the wakes)

A now obsolete defensive technique used by a surface ship when fired upon with multiple torpedoes. Think of the teeth of a comb. Each ‘tooth’ is a wake of a (dumb) torpedo. If you go between them, you hope you will not make contact with a torpedo. Hence, to avoid destruction, ‘comb the wakes’ (go between). That was the strategy for a surface ship such as a destroyer during WWII. Modern torpedoes leave little or no visible wakes and also "home" into a target.

Conformal Array A sonar array whose transducers are attached at various locations about the hull, rather than being concentrated on one location. See also BOW ARRAY.
Conn Originally short for Conning Tower from which the submarine was controlled, it now refers to the Control Room where this function is preformed on nuclear submarines. Also used as a verb as in, "to conn the boat."



(The helm/planes control and the periscope are part of the Control Room)

COW Chief Of (the) Watch. (submarine only) Responsible for coordinating shipboard evolutions such as housekeeping, watch standing, wake-ups, etc. Also controls the BCP (ballast control panel) while underway.
Crazy Ivan In submarines and demonstrated in the movie The Hunt for Red October. Russian submarines would quickly turn 180 degrees while underway to see whether any American submarines were following. Collisions occasionally resulted during the Cold War.
Crews Mess The eating area for a submarine enlisted crew. On a diesel submarine, this area was the forward part of the After Battery Compartment. On a nuclear submarine, it's the middle level of the Operations Compartment.

(Crews Mess on a nuclear sub.)

Critical The condition of a nuclear reactor were a steady-state, self-sustaining nuclear reaction is happening. Power level is neither increasing (super-critical) or decreasing (sub-critical.)
Crush Depth The designed depth at which the pressure hull of a submarine will collapse.




Delta Fourth letter of the phonetic (sound) alphabet. Used when voicing the letter "D" to avoid confusion.
Dink A non-qualified sailor on a submarine who is behind in his qualification process.
Dink List A list, maintained by the COB, of those sailors who are behind on the submarine qualifications.
Ditty bag Any mesh bag, but so named because usually used to contain soiled laundry.
Dive Planes The equivalent to aircraft elevators on a submarine; movable, horizontal surfaces used to control the dive (pitch) angles. Usually there are two pairs of planes, mounted on bow and stern, or on the fairwater (sail) and stern.
Diving trim The term diving trim designates that condition of a submarine when it is so compensated that completing the flooding of the main ballast, safety, and bow buoyancy tanks will cause the vessel to submerge with neutral buoyancy and zero fore-and-aft trim.
Dog To secure tightly, specifically to "dog a hatch" to prevent water from coming in preclude the spread of fire.
Dog watches The 1600-2000 evening watch is customarily split into two two-hour "dog" watches, so that the watch sections rotate rather than being stuck with the same schedule every day. Also permit everyone to get evening chow at a reasonable hour (although First Dog watch standers usually find the better chow is all gone).
Dolphins  Device or insignia indicating "Qualified in Submarines." Called dolphins because of the dolphin fish used in the design.


                              (Officers gold dolphins)                                                                                    (Enlisted silver dolphins)

Dungarees Until very recent times, these were the modern Sailor's work clothes. The term is not modern, however, but dates to the 18th century and comes from the Hindi word dungri, for a type of Indian cotton cloth.




Echo Fifth letter of the phonetic (sound) alphabet. Used when voicing the letter "E" to avoid confusion.
ECM Electronics Countermeasures. Equipment that monitors an enemy or other forces electronic signals to obtain intelligence or, in some cases, to jam it. On submarines, this monitoring equipment is often operated by “Spooks” on clandestine deployments.

(Mast extended on a new Virginia-class submarine.
The dome-topped masts are the main ECM but note
the ribbed masts at the forward end. These are the
 photonic masts that replace older technology periscopes.)

Eight Bells

Aboard Navy ships, bells are struck to designate the hours of being on watch. Each watch is four hours in length. One bell is struck after the first half-hour has passed, two bells after one hour has passed, three bells after an hour and a half, four bells after two hours, and so forth up to eight bells are struck at the completion of the four hours. Completing a watch with no incidents to report was "Eight bells and all is well."

The practice of using bells stems from the days of the sailing ships. Sailors couldn't afford to have their own time pieces and relied on the ship's bells to tell time. The ship's boy kept time by using a half-hour glass. Each time the sand ran out, he would turn the glass over and ring the appropriate number of bells.

Emergency Blow When a sub rapidly blows all of the ballast out of its tanks, resulting in a rapid ascent and an impressive display as the sub breaks the surface.

(USS Oklahoma City SSN-723 conducts an emergency blow)

EOOW Engineer Officer Of the Watch. Pronounced 'ee-ow'.
Eternal Patrol The last and still on-going patrol of a submarine lost at sea. The subs and the sailors are on eternal patrol.



Fairwater The more modern term for the conning tower of a submarine, also called the sail. the Fairwater Planes are diving planes located on a submarine’s fairwater.
Fast Attack Refers to submarines -- designated SSN --  whose primary missions are sea-lane control, anti-shipping operations, anti-submarine warfare, and intelligence operations.
FBM Fleet Ballistic Missile submarine; an earlier term for a Ballistic Missile Submarine, i.e. BOOMER.



A fathom is six feet. Fathom was originally a land measuring term derived from the Ango-Saxon word "faetm" meaning to embrace. In those days, most measurements were based on average size of parts of the body, such as the hand (horses are still measured this way) or the foot (that's why 12 inches are so named). A fathom is the average distance from fingertip to fingertip of the outstretched arms of a man — about six feet. Since a man stretches out his arms to embrace his sweetheart, Britain's Parliament declared that distance be called a "fathom" and it be a unit of measure.  The word was also used to describe taking the measure or "to fathom" something. Today, of course, when one is trying to figure something out, they are trying to "fathom" it.



The appropriate pronunciation for this word is "fo'ksul". The forecastle is the forward part of the main deck. It derives its name from the days of Viking galleys when wooden castles were built on the forward and after parts the main deck from which archers and other fighting men could shoot arrows and throw spears, rocks, etc.
Fouled anchor The fouled (rope- or chain-entwined) anchor so prevalent in our Navy's designs and insignia is a symbol at least 500 years old that has it origins in the British traditions adopted by our naval service.

The fouled anchor was adopted as the official seal of Lord High Admiral Charles Lord Howard of Effingham during the late 1500s. A variation of the seal had been in use by the Lord High Admiral of Scotland about a century earlier.

The anchor (both with and without the entwined rope) is a traditional heraldic device used in ancient British coats of arms. As a heraldic device, it is a stylized representation used merely for its decorative effect.

(A fouled anchor used in a piece of jewlery.)

Foxtrot (1) Sixth letter of the phonetic (sound) alphabet. Used when voicing the letter "F" to avoid confusion.

(2) A class of Soviet diesel-electric submarine. The Foxtrot class was comparable in performance and armament to most contemporary designs. However, its three screws made it noisier than most Western designs.

(A Soviet  Foxtrot submarine at sea.)






The galley is the kitchen of the ship. The best explanation as to its origin is that it is a corruption of "gallery". Ancient sailors cooked their meals on a brick or stone gallery laid amidships.
Gedunk Candy, or a place that sells candy in a short form of Gedunk bar. Also "ice cream."
GDU Garbage Disposal Unit-- A device used to send weighted bags of trash overboard while submerged.

(The GDU unit aboard the USS Albuquerque SSN-706)

GITMO Guantanamo Bay Naval Station on Cuba. A 1934 treaty reaffirming the lease granted Cuba and her trading partners free access through the bay, modified the lease payment from $2,000 in U.S. gold coins per year, to the 1934 equivalent value of $4,085 in U.S. dollars, and made the lease permanent unless both governments agreed to break it or the U.S. abandoned the base property.

(Location of "GITMO" on Cuba.)

Goat Locker The Chief's quarters.
Golf (1) Seventh letter of the phonetic (sound) alphabet. Used when voicing the letter "G" to avoid confusion.

(2) Golf-class diesel-electric ballistic submarine. The submarine was originally designed to carry three R-11 FM ballistic missiles with a range of around 150 km. These were carried in three silos fitted in the rear of the large sail behind the bridge. They could only be fired on the surface but the submarine could be underway at the time. Only the first three boats were equipped with these—the remaining ones were equipped with the longer range R-13 missiles.

(A Soviet Golf-class submarine.)



Hanging Garden Berths suspended from the overhead in a torpedo room in diesel-electric and older nuke subs.
Hatch A vertical opening in a deck sometimes (but incorrectly) also used for any door.
Head The ubiquitous Navy term for all restrooms. It takes its name from the location on sailing ships that sailors would go to relieve themselves (ropes hanging from the bow to the bowsprit over the FIGUREHEAD of the ship.)
Hot, Straight, and Normal A report from the sonar operator that torpedoes just fired are running hot (proper ignition of the engine has occurred), straight (not malfunctioning and steering in a circular run), and normal (no unusual noise are being emitted). Originally used to report performance of steam torpedoes, ca. WWII.
Hotel (1) Eighth letter of the phonetic (sound) alphabet. Used when voicing the letter "H" to avoid confusion.

(2) A class of Soviet nuclear submarine designed to carry the D-2 launch system and R-13 missiles. The Hotel design was based on the Project 627 November class, the first Soviet nuclear submarines, modified by adding the missile compartment from the Golf class submarines. Additionally, the Hotels had small horizontal hydroplanes for better maneuverability, and more reliable electro-hydraulic command control surfaces for high-speed underwater operations with reduced noise. The D-2 launch system on the Hotels placed three R-13 missiles in vertical containers directly behind the sail. The submarine had to be surfaced to launch, but all three missiles could be fired within 12 minutes of surfacing. The infamous K-19 was a Hotel-class.

(This is the infamous K-19, a Hotel-class Soviet submarine)

Hotel Services Power, water, and steam used for cooking, heating, laundry, or other non-engineering or non-propulsion purposes.



India (1) Ninth letter of the phonetic (sound) alphabet. Used when voicing the letter "I" to avoid confusion.

(2) A two-ship class of Soviet submarines, the India class of boats were designed for high surface speeds, and had tracks on their hulls so they could operate on the ocean floor. The submarines of this class were designed to function as a base for two Poseidon DSRV's (Deep Submergence Rescue Vehicles), which could rescue the crew of sunken submarines. While the India class boats have been seen going to the aid of Russian Submarines involved in accidents, they have also been observed working in support of Russian Spetsnaz special operations. The boats had decompression chambers and medical facilities on board. Two vessels of this class were built for the Soviet navy. Both were scrapped in the 1990s.

(An artist conception of the use of India-class submarines.)

Intercom Systems

7MC — General Announcing 2-way - Ship Control or Maneuvering Announcing

21MC — Captain's Command  2-way - Bridge, Conn & other stations

22MC — Radio Room / Electronic Control 2-way

27MC — Sonar Control 2-way - Sonar Supervisor

31MC — Escape Hatch Announcing 2-way

47 MC — Weapons - Fire Control & Torpedo Room

On Diesel boats:

The general announcing system is comprised of two voice communications circuits, one-way (1MC) and two-way (7MC). The same amplifier equipment is used for both circuits. Generally, one channel is used for the 1MC and one for the 7MC, but in an emergency both circuits may be operated through either of the two individual amplifier channels.

(see Announcing Systems)


Irish Pennant Loose thread on uniform.



Jacking Gear The machinery used to jack a shaft. May also be used to lock the shaft.
Jin-Class Submarine

The Type 094 (NATO reporting name: Jin-class) is a class of nuclear powered ballistic missile submarine developed by the Chinese People's Liberation Army's Navy and capable of carrying 12 of the more modern JL-2s missiles with a range of approximately 4,300 nautical miles. The first-of-class was launched in July 2004. Four submarines are believed to have been constructed and are believed to incorporate a great deal of Russian technology.

Juliet Tenth letter of the phonetic (sound) alphabet. Used when voicing the letter "J" to avoid confusion.



Kilo (1) Eleventh letter of the phonetic (sound) alphabet. Used when voicing the letter "K" to avoid confusion.

(2) Also, the NATO reporting name for a Russian military Type 636 diesel-electric submarine that first entered service in the early 1980s. This submarine is designed for anti-submarine warfare (ASW) and anti-surface-ship warfare (ASuW) and also for general reconnaissance and patrol missions. The Type 636 submarine is considered to be to be one of the quietest diesel submarines in the world. The Kilo will be succeeded by the Lada class submarine, which began sea trials in 2005. Maximum depth is 300m (984 feet). Speed is 11kt when surfaced and 20kt when submerged. Range is 7,500 miles when snorkeling at 7kt and 400 miles when submerged at 3kt.
The submarine is equipped with six 533mm (21 inch) forward torpedo tubes carries 18 torpedoes with six in the torpedo tubes and 12 stored on the racks. Alternatively the torpedo tubes can deploy 24 mines.

(A Kilo-class submarine -- this one operated by the Iranian Navy -- cruises on the surface.)



Ladder Stairs aboard ship. Found in a "ladder well" (stairwell).
Lifer A name given to both officers and enlisted men who love the navy and make it clear they want to be in for 20 or more years. Lifers will try to convince others to re-enlist. Also lifers say things like "there is nothing a sailor needs that is not in his sea-bag" this usually is a comment implying a sailor does not need to see his spouse or children.
Lima Twelfth letter of the phonetic (sound) alphabet. Used when voicing the letter "L" to avoid confusion.
Lucky Bag The lucky bag is defined as a where loose items from a ship are stored until being returned to the owner. According to the 1940 edition of the Blue Jackets' Manual (a handbook for U.S. Navy enlisted personnel), "The lucky bag is a place where the police petty officers stow for safe-keeping effects that are found adrift about the ship. All clothes, etc., found about the decks are placed in the lucky bag. When clothes are piped down, the police petty officer attends and takes care of all clothes not called for and places these in the lucky bag. All effects in this bag belong to the person who lost them. At frequent intervals the lucky bag is opened and the effects distributed to the owners. Where persons have been guilty of carelessness in leaving their effects adrift, they are placed on the report."



Main ballast tanks Tanks that are provided primarily to furnish buoyancy when the vessel is in surface condition and that are habitually carried completely filled when the vessel is submerged.
Maneuvering Room The area or compartment where speed and other engineering functions are performed in response to orders from the bridge or operations.

On diesel submarines, the engines drove electric generators. Maneuvering was primarily an electric console that allocated power to/from batteries and generators to the main propulsion motors.

On nuclear powered boats, maneuvering is supervised by the engineering officer of the watch with one petty officer manning each of these three consoles to monitor and control the submarine's entire nuclear power plant. The console on the left controls the steam turbines. The center console is the nuclear reactor control panel, while the right-hand console controls the electrical system.

Mark-48 The Mark 48 and its improved ADCAP (Advanced Capability) variant are heavyweight submarine-launched torpedoes. They were designed to sink fast, deep-diving nuclear-powered submarines and high-performance surface ships. This is the primary U.S. submarine torpedo in use today. Mk-48 and Mk-48 ADCAP torpedoes can be guided from a submarine by wires attached to the torpedo. They can also use their own active or passive sensors to execute programmed target searches, acquisition and attack procedures. The torpedoes are designed to detonate under the keel of a surface ship, breaking the ship's back and destroying its structural integrity. In the event of a miss, it can circle back for another attempt.

(A Mark 48 torpedo being loaded on a fast attack nuclear submarine.)

Mast Preceded by Captain's or Admiral's, but these are generally not spoken. A form of non-judicial punishment in which a sailor finds himself standing tall in front of the old man when he really screws the pooch. Green felt is usually abundant.
Mid Rats: (Midnight Rations) Meal served around midnight for those crewmembers going on or off watch.
Mike Thirteenth letter of the phonetic (sound) alphabet. Used when voicing the letter "M" to avoid confusion.
Main Coolant Part of the nuclear propulsion system, this system circulates nearly-pure water through the reactor where it picks up heat and transfers it to the secondary, or steam system, were the energy is used to turn turbines and, ultimately, the ships propeller. This coolant system is pressurized to prevent boiling. See PWR.
Momsen Lung

The Momsen lung was a primitive underwater rebreather used before and during World War II by American submariners as emergency escape gear. The Momsen lung was invented by Charles B. Momsen (nicknamed "Swede"). Submariners would train in a 100-foot (30-meter) deep escape training tower using this apparatus. It was first introduced as standard equipment on P- and Salmon-class boats. The device recycled the breathing gas by using a counter-lung containing soda lime to scrub carbon dioxide. The lung was initially filled with oxygen and connected to a mouthpiece via twin hoses containing one-way valves: one for breathing in and the other for breathing out.

(Submarine trainees using the Momsen Lung)

Mooring Line Lines used to tie the ship to the pier or to another ship. Mooring lines are numbered from forward aft; the direction they tend (lead) is also sometimes given. ‘Number one mooring line’ typically is made fast at the bow, and tends straight across to the pier or other ship. Spring lines tend forward or aft of their attachment point.
Mustang (USN) An officer who has 'come up through the ranks', i.e. started out as an enlisted man and earned a commission.



Negative tank The Negative Tank is a variable ballast tank providing negative buoyancy and initial down-angle. Submarines normally will operate submerged in neutral buoyancy and without trim when the negative tank is nearly empty. It is used to reduce the time required in submerging from surface condition, to reduce the time required to increase depth while operating submerged, and to prevent broaching when decreasing depth. It may be blown or pumped.
November  Fourteenth letter of the phonetic (sound) alphabet. Used when voicing the letter "N" to avoid confusion.
Nose-coner A somewhat derogatory title, used by nuclear trained submarine personnel, for all non-nuclear or "forward of the reactor compartment" (the nose cone of the submarine) working crew. 
Nuke (1) A ship propelled by nuclear power

(2) A person who has been specially trained and qualified as a nuclear operator in the ship's engineering department. Also the opposite of a "nose-coner."

Nuke Striker Pejorative term used by nukes to describe a nose-coner that asks endless questions about the operations of the nuclear power plant. Strikers are sailors that enlist without a guaranteed rate (job), with the intention of floating around until they find a department where they fit in. However, you can't strike for Nuclear Field.



Oscar (1) Fifteenth letter of the phonetic (sound) alphabet. Used when voicing the letter "O" to avoid confusion.

(2) Oscar-class were Soviet nuclear-powered cruise missile submarines. They were the largest cruise missile submarines in service until the new (rebuilt) Ohio class SSGN cruise missile submarine on October 15, 2007, and the third largest submarines as submarines in terms of displacement and length. Only the Typhoon class Soviet/Russian submarines and the American Ohio class submarines are larger.

(Oscar-class submarine underway.)

Ohio-Class The Ohio class is a class of nuclear-powered submarines used by the United States Navy. The United States has 18 Ohio class submarines: 14 are nuclear-powered SSBNs (ballistic missile submarines), each armed with 24 Trident II SLBMs; they are also known as "Trident" submarines, and provide the sea-based leg of the nuclear triad of the United States strategic nuclear weapons arsenal. Four are nuclear-powered SSGNs (cruise missile submarines), each capable of carrying 154 Tomahawk cruise missiles with conventional warheads.


(Ballistic missile version.)                                                                                                                                                   (SSGN fires Tomahawk.)

Overhead What a civilian would call the ceiling. Essentially, the underside of the deck above.



Papa Sixteenth letter of the phonetic (sound) alphabet. Used when voicing the letter "P" to avoid confusion.
Passageway  A hallway aboard ship.

Pea Coat

Sailors who have to endure pea-soup weather often don their pea coats but the coat's name isn't derived from the weather. The heavy topcoat worn in cold, miserable weather by seafaring men was once tailored from pilot cloth — a heavy, course, stout kind of twilled blue cloth with the nap on one side. The cloth was sometimes called P-cloth for the initial letter of "pilot" and the garment made from it was called a p-jacket — later, a pea coat. The term has been used since 1723 to denote coats made from that cloth.

Ping (1) To transmit on active sonar, or the sound or signal made by same.

(2) (RM) To recognize someone or something.

(3) To bounce or wander around aimlessly.

Plank Owner  A member of the original commissioning crew of a ship. Traditionally, when a plank owner leaves, he is presented with a piece of the wooden decking. Since the advent of all-metal warships, however, a common plank owner memento is a plaque bearing a brass or bronze escutcheon constructed from the machining scraps of the propellers.
Plimsoll Mark A mark on the side of a ship’s hull which indicates a certain level of loading and, therefore, draft.

(Plimsoll marks on a ship's hull.)

Poopie Suit Blue coveralls worn by sub crews (and, recently, surface ships) underway.
Port The left side. (see Starboard)
Pressure Hull The watertight, pressure-bearing structure that makes up the living and working area of a submarine.
PQS Personnel Qualification System. A method of formalizing and tracking the qualification progress of personnel toward watchstation certification. Often abbreviated as 'Qual System'. Used by all warfare specialties, but has reached its ultimate in the submarine service.
PWR Pressurized Water Reactor. A type of nuclear plant used on all U.S. Navy ships that uses pure water as a moderator/coolant and enriched uranium as the fuel. All U.S. nuclear submarines have one reactor and aircraft carriers have two (with the exception of the U.S.S. Enterprise, which has eight, older style ones.) Modern reactors are designed to last the life of the ship without a nuclear re-fueling.

(Typical functional diagram of a PWR.)



Qual Card A listing of necessary PQS qualification points. Each completed goal is acknowledged by the signature of the appropriate duty Chief or other authorized signer. May be a single piece of paper or a bound book.
Quebec Seventeenth letter of the phonetic (sound) alphabet. Pronounced "Kay-bec" and used when voicing the letter "Q" to avoid confusion.



Rag-hat Junior sailor, E-6 (First Class Petty Officer) and below. Refers to the sailor’s white hat.
RCH An extremely small unit of measurement, normally used by nuclear trained submariners particularly Reactor Operators as in, "turn that adjustment just two RCHs." The actual meaning of the acronym is beyond the scope of this glossary.
Rigged for dive A submarine is rigged for dive by so compensating the vessel and preparing the hull openings and machinery that the vessel can be quickly and safely submerged and controlled by flooding the main ballast tanks, using the diving planes, and, on diesel powered boats, operating on battery-powered main motors.
Romeo (1) Eighteenth letter of the phonetic (sound) alphabet. Used when voicing the letter "R" to avoid confusion.

(2) Romeo is a class of Soviet diesel-electric submarine, built in 1950s. The origin of the Romeo class can be traced to the World War II German Type XXI Elektroboot U-boat. At the end of World War II, the Soviets obtained several Type XXIs, from which they were able to obtain certain key technologies. These technologies assisted in the design of the Zulu- and Whiskey-class. Further improvements on the design led to the Romeo class. Only 20 of the Soviet Union's originally intended 560 were completed between October 1957 and the end of December 1961 because of the introduction of the nuclear submarine into the Soviet Navy. By today's standards, the Romeo class submarine is considered obsolete, but still has some value as training and surveillance vessels.



Sail The portion of a submarine above the round hull. Often, and mistakenly, called the conning tower from the old diesel-boat days when this structure did indeed hold a compartment called the "conning tower. The sail houses retractable masts and provides roll stability and a ships bridge above the water when surfaced. 
Sail Planes Wing-like fins off the side of the sail. Used, with stern planes, for depth control and change. The latest submarines have these replaced with planes mounted on the hull at the bow.
Safety tank The Safety Tank is a heavily reinforced main ballast tank arranged to permit pumping as well as quick blowing to regain positive buoyancy. Under normal submerged conditions, the blowing or pumping of this tank will bring the conning tower above the surface.
Scram Emergency shutdown of a nuclear reactor. The origin of the term has various possibilities but they all date from the dawn of nuclear power.



A scuttlebutt is a drinking fountain. The origin of the word "scuttlebutt," which is nautical parlance for a rumor, comes from a combination of "scuttle" — to make a hole in the ship's hull and thereby causing her to sink —- and "butt" — a cask or hogshead used in the days of wooden ships to hold drinking water. The cask from which the ship's crew took their drinking water — like a water fountain — was the "scuttlebutt". But, since the crew used to congregate around the "scuttlebutt", that is where the rumors about the ship or voyage would begin. Thus, then and now, rumors are talk from the "scuttlebutt" or just "scuttlebutt".
Scrubber (USN Submarines) On a submarine, removes or "scrubs" CO2 out of the air.

SEIE (Submarine Escape and Immersion Equipment)


The MK-10 Submarine Escape Immersion Equipment, a combined whole-body suit and one-man life raft, is designed to provide submariners protection against hypothermia. It is rapidly replacing the Steinke Hood rescue device. This system increases the capability for safe escape from a depth of 350 feet to 600 feet, while reducing the overall risk of injury to escapers from disabled submarines at all depths.
The SEIE MK-10, is a British-designed suit. In 2000 the USS TOLEDO became the first US submarine to have the fully operational and certified British escape system. The reconfiguration of escape trunks and training of the crews are requirements prior to installing the new system.

(Mk10, SEIE)

Shaft Alley Engineering space aft of engine rooms, where propeller shafts pierce the hull. Location of shaft seals, etc.
Shift Colors When a ship moors, the national colors are broken out on the stern, the Jack is broken out on the bow, and the national colors ("steaming colors") are hauled down at the masthead, all at the instant the first line goes over. When the ship gets underway, as soon as the last line is cast off the dock, the Jack and colors are struck at bow and stern while the steaming colors are broken at the masthead.
Shipshape Also seen as "Shipshape and Bristol fashion." The desired condition of any ship or unit; the maintenance of seamanlike appearance. Every piece of gear stowed neatly, "a place for everything, and everything in its place."
Sierra Nineteenth letter of the phonetic (sound) alphabet. Used when voicing the letter "S" to avoid confusion.
Skimmers Any sailor who serves on a surface ship (i.e., non-submariner.) Comes from the fact that these sailors only "skim" the surface of the ocean rather than use all of it.
Smoking lamp The exact date and origin of the smoking lamp has been lost. However, it probably came into use during the 16th Century when seamen began smoking on board vessels. The smoking lamp was a safety measure. It was devised mainly to keep the fire hazard away from highly combustible woodwork and gunpowder. Most navies established regulations restricting smoking to certain areas. Usually, the lamp was located in the forecastle or the area directly surrounding the galley indicting that smoking was permitted in this area. Even after the invention of matches in the 1830s, the lamp was an item of convenience to the smoker. When particularly hazardous operations or work required that smoking be curtailed, the unlighted lamp relayed the message. "The smoking lamp is lighted" or "the smoking lamp is out' were the expressions indicating that smoking was permitted or forbidden.
The smoking lamp has survived only as a figure of speech. When the officer of the deck says "the smoking lamp is out" before drills, refueling or taking ammunition, that is the Navy's way of saying "cease smoking."
SONAR An acronym for SOund Navigation And Ranging, and is the eyes and ears of a submarine. Somewhat similar to radar but uses sound waves rather than electromagnetic radiation. Submarines rarely use active sonar (pinging) since this will give a way a ships position.

(The sonar room or "shack" aboard a nuclear submarine.)

SOSUS SOund SUrveillance System. A land-based system of seabed hydrophones and sophisticated analysis equipment, used to monitor worldwide movements of ships and submarines.
Sound Powered Phones A sound-powered telephone is a communication device that allows users to talk to each other with the use of a handset, similar to a conventional telephone, but without the use of external power. This technology has been used for at least six decades for both routine and emergency communication on ships to allow communication between key locations on a vessel even if power, including batteries, is no longer available. A sound-powered phone circuit can have two or more stations on the same circuit. The circuit is always live, thus a user simply begins speaking rather than dialing another station. Sound-powered telephones are not normally connected to a telephone exchange. The system is divided into two circuits, the XJA (handset) used for routine ship's service communication, and the JA (headset) circuits used on all battle control and other functional stations and uses.
Spooks "Sailors" who were specialist in electronic intelligence. They were not part of the regular ships company and would report on board just before the submarine would leave on patrol.


The Vikings called the side of their ship its board, and they placed the steering oar, the "star" on the right side of the ship, thus that side became known as the "star board." It's been that way ever since. And, because the oar was in the right side, the ship was tied to the dock at the left side. This was known as the loading side or "larboard". Later, it was decided that "larboard" and "starboard" were too similar, especially when trying to be heard over the roar of a heavy sea, so the phrase became the "side at which you tied up to in port" or the "port" side.
Steinke Hood A Steinke hood is a device designed to aid escape from a sunken submarine, essentially an inflatable life jacket with a hood that completely encloses the wearer's head, trapping a bubble of breathing air. An advancement over its predecessor, the Momsen lung, it was standard equipment in all submarines of the United States Navy throughout the Cold War period. The U.S. Navy has replaced Steinke hoods on U.S. submarines with escape suits called Submarine Escape Immersion Equipment.

(The standard Steinke Hood.)



Tango Twentieth letter of the phonetic (sound) alphabet. Used when voicing the letter "T" to avoid confusion.
Target In submarine parlance, this is any this is any surface vessel that floats around in two dimensions.

The Tomahawk® Land Attack Missile (TLAM) is an all-weather, long range, subsonic cruise missile used for land attack warfare, launched from U. S. Navy surface ships and U.S. Navy submarines from either vertical launch tubes or conventional torpedo tubes.

Tomahawk carries a nuclear or conventional payload. The conventional, land-attack, unitary variant carries a 1,000-pound-class warhead (TLAM-C) while the sub-munitions dispenser variant carries 166 combined-effects bomblets (TLAM-D).

These cruise missiles are designed to fly at extremely low altitudes at high subsonic speeds, and are piloted over an evasive route by several mission tailored guidance systems.


Torpedo The primary weapon of submarines, these are self-propelled devices that are launched from torpedo tubes -- located amidship lower level on fast attacks and in the bow on FBMs. Various methods of propulsion and guidance are used. See Mark 48.

Torpedo Room That part of a submarine that contains the tubes used to launch torpedoes or, in modern nuclear subs, Tomahawk cruise missiles. On the old diesel boats, there was originally both a forward (bow) and aft (stern) torpedo rooms. Nominally, the forward room had six (6) tubes and the aft had four (4) tubes. Modern fast attack submarines have four tubes mounted amidships, angled out port and starboard.


  (Forward torpedo room on a diesel boat)                                               (One of the tubes on the USS Albuquerque [SSN-706], a nuclear fast attack.)

Trident (Trident II)

The Trident missile is a submarine-launched ballistic missile (SLBM) designed by Lockheed Martin Space Systems in the United States with multiple independently-targetable reentry vehicle (MIRV) capability. It is armed with nuclear warheads and is launched from nuclear-powered ballistic missile submarines (SSBNs.)

The first eight Ohio-class subs were built with the Trident I missiles. Trident were also retrofitted onto 12 SSBNs of the James Madison and Benjamin Franklin classes, replacing Poseidon missiles.

The second — and current — variant of the Trident is more sophisticated and can carry a heavier payload. It is accurate enough to be a first strike, counterforce, or second strike weapon. All three stages of the Trident II are made of graphite epoxy, making the missile much lighter. The Trident II was the original missile on Ohio SSBNs from USS Tennessee (SSBN-734) on. The D5 missile is currently carried by fourteen Ohio class SSBNs. Lockheed Martin has carried out 130 consecutive successful test launches of the D5 missile since 1989, according to a company press release.


(A Trident D5 missile is launched from an Ohio-class submarine.)

Trim A mechanism or system of a submarine which compensates for imbalances fore and aft or port and starboard, so as to maintain level attitude. Can be a noun (for the system or static tendency) or a verb, to use the system to change longitudinal (fore and aft) or lateral (side to side) balance.



Uniform Twenty-first letter of the phonetic (sound) alphabet. Used when voicing the letter "U" to avoid confusion.
UQC The underwater telephone also known as UQC , or "Gertrude" was developed by the U.S. Navy after World War I, the UQC underwater telephone is used on all manned submersibles in operation. Voices communicated through the UQC are heterodyned to a high pitch for acoustic transmission through water.



Variable ballast tanks Ballast tanks that are not habitually carried completely filled when submerged and whose contents may be varied to provide weight compensation are known as variable ballast tanks. These ballast tanks are constructed to withstand full sea pressure.
Vertical Launch Tubes Vertical tubes, located in the forward part of the outer hull of 688i-class (final flight of the USS Los Angeles class) and later submarines that are used to house Tomahawk and other missiles. These can be fired underwater.

(Vertical launch tube doors are shown open in this 688i-class submarine.)

Victor (1) Twenty-second letter of the phonetic (sound) alphabet. Used when voicing the letter "V" to avoid confusion.

(2) A class of Soviet nuclear-powered submarine that was originally put into service by the Soviet Union around 1967. Victor-class subs featured a teardrop shape, which allowed them to travel at high speed. These vessels were primarily designed to protect Soviet surface fleets and to attack American ballistic missile subs, should the need ever arise.

(A Soviet Victor III-class submarine.)



"Wailing Wall" The area next to the periscopes where all the alarms were located. (Sturgeon-class submarines)
"Waltzing the One-Eyed Window"  The action of the Watch officer as he was swinging the periscope 360 degrees as the scope broke the surface to find any surface contacts. (submarines with single eyepiece periscopes)

The standing of duty shifts. The practice varies, but in the US Navy, the watch rotation is as follows:

0000-0400 – Midwatch

0400-0800 – Morning Watch

0800-1200 – Forenoon Watch

1200-1600 – Afternoon Watch

1600-1800 – First Dogwatch

1800-2000 – Second Dogwatch

2000-2400 – Evening Watch (aka First Watch)

The purpose of the dogwatches is to permit the watch standers to eat the evening meal. These watches are said to be "dogged."

Whiskey Twenty-third letter of the phonetic (sound) alphabet. Used when voicing the letter "W" to avoid confusion.



X-Ray Twenty-fourth letter of the phonetic (sound) alphabet. Used when voicing the letter "X" to avoid confusion.



Yankee (1) Twenty-fifth letter of the phonetic (sound) alphabet. Used when voicing the letter "Y" to avoid confusion.

(2) The Yankees were the first class of Soviet subs to have comparable ballistic missile firepower to their American counterparts. Yankee subs were quieter than their Hotel-class predecessors (but still louder than NATO submarines) and had smoother lines that improved their submerged performance. The ships were armed with 16 ballistic missiles during the Cold War, and served in the Soviet front lines: in the 1970s up to three Yankees were continually stationed in a "patrol box" east of Bermuda and off the US Pacific coast.

(Soviet Yankee-class submarine on the surface.)



Zulu (1) Twenty-sixth letter of the phonetic (sound) alphabet. Used when voicing the letter "Z" to avoid confusion.

(2) The Soviet Navy's Project 611, also known by their NATO reporting name of Zulu-class, were designed as attack submarines, but six were converted in 1956 to become the world's first ballistic missile submarines, one armed with a single F-11FM Scud missile and five others with two Scuds each. The missiles were too long to be contained in the boat's hull, and extended into the enlarged sail. Soviet submarine B-67 successfully launched a missile on 16 September 1955. The design was influenced by the German Type XXI U-boat of the World War II era.