Active Sonar — The determination of a contact’s bearing and range by pinging a sound pulse into the ocean and listening for the reflection of the ping from the target. The time interval between transmission and reception gives target range using the speed of sound in water. The direction of the return pulse indicates the target bearing. Generally not used by submarines since it gives away the ship’s position.
Anechoic Coating — A thick foam coating attached to the outside of the hulls of some submarines. It absorbs incoming active sonar pulses without reflecting them back, while damping out internal noises before they can get outside the ship. Analogous to stealth radar absorptive material on a stealth aircraft.
Angle On The Bow — The angle between an observer’s line-of-sight to a target ship and the target’s heading. A ship coming dead on has an angle on the bow of zero degrees. If the contact is going on a course at a right angle to his bearing from the oh server, the angle on the bow is port (or starboard) 90 degrees.
ASH (Anti-Self Homing) — A torpedo interlock that measures the distance from the firing ship. If the torpedo comes back toward the firing ship, at 80 % of the return trip, the ASH interlock will shut down the unit, and it floods and sinks.
ASW — (1) Antisubmarine warfare. (2) Auxiliary seawater system.
ASWSOW — Antisubmarine warfare standoff weapon. A supersonic solid rocket fueled missile launched from a submarine at either a surfaced or submerged target. Also called “Ow-sow.”
Baffles — A “cone of silence” astern of most submarines where sonar reception is hindered by engines, turbines, screws, and other mechanical equipment located in the aft end of a submarine.
Ballast Tank — Tank that is used solely to hold seawater ballast, weight that allows a ship to sink, or, when blown, allows a ship to be light enough to surface.
Battleshort — A condition in which the nuclear reactor’s safety interlocks are removed. Used only in a severe emergency or in battle, when an accidental reactor shutdown is more dangerous to the ship due to loss of propulsion than the potential risk of a reactor meltdown. Only the captain can order Battleshort.
Bearing — Direction to a contact, expressed in degrees. A contact to the north is at a bearing of 000. A contact to the east is at 090, etc.
Bigmouth Antenna — Slang name for the AN BRA-34 multi frequency antenna. A radio antenna suitable for transmission or reception of several frequencies including HF, VHF, and UHF. Shaped like a telephone pole, it protrudes from the sail about 25 feet.
Bridge — Small space at the top of a submarine’s sail used for the Officer of the Deck to control the movement of the ship when on the surface. The height allows a better view of the surroundings of the ship.
Bridge Access Trunk — Tunnel from the interior of the submarine to the bridge.
Broadband — Noise containing all frequencies; white noise, such as heard in radio static, rainfall, or a waterfall. Broadband detection range is high for surface ships, which are noisy. Broadband detection range is low for submarines, usually less than five miles, due to quiet submarine designs.
Bubblehead — Derogatory slang for submariner, used by aviators (Airdales) and surface sailors (skimmers).
Check Fire — Order to abort a pending weapon launch.
CINCPAC — Commander-in-Chief Pacific. Admiral in command, U.S. Pacific Forces.
Clamshells — The steel or fiberglass hinged plates that cover the top of the bridge cockpit when rigged for dive and are opened when rigged for surface. When shut, the top of the sail is completely smooth.
Clear Datum — Tactical euphemism meaning run away.
C.O. (Commanding Officer) — Official title of the captain of a ship.
COMMSAT — Communications satellite in a geosynchronous orbit that sends and relays Navy radio traffic.
Contact — Another ship, detected by visual means, sonar, or radar. A contact can be hostile or friendly.
Course — The direction a ship is going measured in true compass degrees. North is 000. East is 090. South is 180, etc.
Critical — The point that a nuclear reactor’s fission rate is constant without an external source of neutrons. The chain reaction keeps fissions continuing using neutrons from fissions.
Deck — (1) Floor of the submarine. Each compartment is either two or three decks high. (2) Responsibility for the physical operation of the ship. The officer who has the Deck makes decisions about equipment lineups, how to run and operate ship systems, etc.” while the conning officer concerns himself with ship navigation, course, speed, and relationship to the target. Usually the OOD has both the Deck and the Conn.
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.
Dogs — Banana-shaped pieces of metal that act as clasps to keep a hatch shut.
Dolphins — Pin worn above left pocket of submariner’s uniform, indicating the person is qualified in submarines. Qualification typically takes one gruelling year. Enlisted men wear silver dolphins; officers wear gold. Dolphins, when not worn on the pocket, are a general symbol of the Submarine Force.
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.
EMBT Blow — Emergency main ballast tank blow.
Emergency Blow — Blowing the water out of the main ballast tanks using ultra-high-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 Propulsion Motor (EPM) — A large DC motor aft in the engine room capable of turning the shaft to achieve 3 knots using battery power alone. An electricity hog.
EO (Electrical Operator) — Enlisted nuclear-qualified watch stander 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 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.
ESGN — Ship’s inertial navigation system using a small metal ball that spins at about 10,000 RPM to gyroscopically maintain a constant reference (north).
ESM (Electronics Surveillance Measures) — The gathering of intelligence through the analysis of enemy signals, including radars and radio transmitters.
EWS (Engineering Watch Supervisor) — A Chief who is a roving supervisory watch stander in the engineering spaces. Reports to the EOOW.