User Guide

APPENDIX B: GLOSSARY OF
TERMS
Angle on the Bow (AOB) Aspect of ship referenced to a line between bow own ship and the contact,
measured 0 to 180 degrees port or starboard.
Bow Front of the ship.
Broadband Acoustic signal consisting of a broad range of frequencies.
Cavitation Bubbles created and collapsed at a propeller due to pressure changes;
causes a large amount of noise.
Coordinate Position of a point,often measured in latitude and longitude.
Countermeasure Device used to interfere with a torpedo detecting its target or with a sonar
that is tracking a contact.
Course Direction of travel, measured 0 to 360 degrees from north.
Covert Unknown to others; not openly shown.
Datum Last known position.
Dead reckon (DR) Approximation of ship position calculated using measured speed and
heading.
Engine order telegraph (EOT) Device used to send throttle (speed) orders to the engine room.
Fairwater Structure on top of submarine used to protect masts and antennas.
Fathom (fm) Measure of depth of water; 1fm = 6 ft = 1.8 m.
Fathometer Active sonar device used to measure water depth.
Fix Location of ship determined using external reference.
Flank Maximum attainable speed.
Heading Direction of travel, measured 0 to 360 degrees from north.
Helmsman Operator responsible for steering and relaying speed orders.
Hydrophone Electronic acoustic device used to receive sound.
Knots (kt) Measure of speed in water; 1 kt = 1 nautical mile/hr = 1.14 miles/hr =
1.82 kilometers/hr.
Launch basket The area from which to conduct an attack.
Leg Period of time on a given course and speed.
Mark Term describing the sending of bearings and/or range to a contact from a
sensor to the TMA function.
Narrowband Acoustic signal separated into narrow frequency windows.
Nautical mile (nm) Measure of distance equal to 1 minute of latitude; 1nm = 2000 yards =
1.14 miles = 1.82 kilometers.
Planesman Operator responsible for controlling the bow and stern planes of the
submarine.
Port Left side of ship as seen facing forward.
Signal-to-noise ratio (SNR) Logarithmic ratio of signal to interfering noise used to measure acoustic
noise interference.
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