GLOSSARY
Acoustic intercept: a passive (listening only) sonar specifically designed to give warning when the submarine is “pinged” by an enemy active sonar. The latest version is the WLY-1.
Active out-of-phase emissions: a way to weaken the echo that an enemy sonar receives from a submarine’s hull by actively emitting sound waves of the same frequency as the ping but exactly out of phase. The out-of-phase sound waves mix with and cancel those of the echoing ping.
ADCAP: Mark 48 Advanced Capability torpedo. A heavyweight, wire-guided, long-range torpedo used by American nuclear submarines. The Improved ADCAP has an even longer range, and an enhanced (and extremely capable) target homing sonar and software logic package.
AIP: Air Independent Propulsion. Refers to modern diesel submarines that have an additional power source besides the standard diesel engines and electric storage batteries. The AIP system allows quiet and long-endurance submerged cruising, without the need to snorkel for air because oxygen and fuel are carried aboard the vessel in special tanks. For example, the German Class 212 design uses fuel cells (see below) for air independent propulsion. Some other systems burn high-test hydrogen peroxide, which has its own oxygen built in chemically.
Alumina casing: an extremely strong hull material that is less dense than steel, declassified by the U.S. Navy after the Cold War. A multilayered composite foam matrix made from ceramic and metallic ingredients.
Ambient sonar: a form of active sonar that uses, instead of a submarine’s pinging, the ambient noise of the surrounding ocean to catch reflections off a target. Noise sources can include surface wave- action sounds, the propulsion plants of other vessels (such as passing neutral merchant shipping), or biologics (sea life). Ambient sonar gives the advantages of actively pinging but without betraying a submarine’s own presence. Advanced signal-processing algorithms and powerful on-board computers are needed to exploit ambient sonar effectively.
ARCI: Acoustic Rapid COTS Insertion; COTS stands for commercial-off-the-shelf. The latest software system designed for
ASDS: Advanced SEAL Delivery System. A new battery-powered mini-submarine for the transport of SEALs (see below) from a parent nuclear submarine to the forward operational area and back, within a warm and dry shirtsleeves environment. This permits the SEALs to go into action well rested and free from hypothermia — real problems when the SEALs must swim great distances, or ride while using scuba gear on older free-flooding SEAL Delivery Vehicle underwater “scooters.”
ASW: Antisubmarine warfare. The complex task of detecting, localizing, identifying, and tracking enemy submarines, in order to observe and protect against them in peacetime, and to avoid or destroy them in wartime.
Auxiliary maneuvering units: small propulsors at the bow and stern of a nuclear submarine, used to greatly enhance the vessel’s maneuverability. First ordered for the USS
Bipolar sonar: a form of active sonar in which one vessel emits the ping while one or more other vessels listen for target echoes. This helps disguise the total number and location of friendly vessels present.
CACC: Command and Control Center. The modern name for a submarine’s control room.
CAPTOR: a type of naval mine, placed on or moored to the seabed. Contains an encapsulated torpedo, which is released to home on the target.
CCD: Charge-Coupled Device. The electronic “eyes” used by low-light-level television, night-vision goggles, etc.
COB: Chief of the Boat (pronounced “cob”). The most senior enlisted man on a submarine, usually a master chief. Responsible for crew discipline, and for proper control of ship buoyancy and trim at battle stations, among many other duties.
Deep scattering layer: a diffuse layer of biologics (marine life) present in many parts of the world’s oceans, which causes scattering and absorption of sound. This can have tactical significance to undersea warfare forces by obscuring passive sonar contacts and causing false active sonar target returns. The layer’s local depth, thickness, and scattering strength are known to vary by many factors, including one’s location on the globe, the sound frequency being observed, the season of the year, and the hour of the day. The deep scattering layer is typically several hundred feet thick, and lies somewhere between one thousand and two thousand feet of depth during daylight, migrating shallower at night.
Deep sound channel: a thick layer within the deep ocean in which sound travels great distances with little signal loss. The core (axis) of this layer is formed where seawater stops getting colder with increasing depth (the bottom of the thermocline, see below) and water temperature then remains at a constant just above freezing (the bottom isothermal zone, see below). Because of the way sound waves diffract (bend) in response to temperature and pressure, noises in the deep sound channel are concentrated and propagate for many miles without loss to surface scattering or seafloor absorption. Typically the deep sound channel is strongest between depths of about three thousand and seven thousand feet.
ELF: Extremely Low Frequency. A form of radio that is capable of penetrating seawater, used to communicate (one way only) from a huge shore transmitter installation to submerged submarines. A disadvantage of ELF is that its data rate is extremely slow, only a few bits per minute.
EMBT blow: Emergency Main Ballast Tank blow. A procedure to quickly introduce large amounts of compressed air (or fumes from burning hydrazine) into the ballast tanks in order to bring a submerged submarine to the surface as rapidly as possible. If the submarine still has propulsion power, it will also try to drive up to the surface using its control planes (called planing up).
EMCON: Emissions Control. Radio silence; also applies to radar, sonar, laser, or other emissions that could give away a vessel’s presence.
EMP: Electromagnetic Pulse. A sudden, strong electrical current induced by a nuclear explosion. This will destroy un-shielded electrical and electronic equipment and ruin radio reception. There are two
