Marine Electronics Glossery  

we thought may be helpful to you in choosing the right marine electronic equipment for your needs.



ANTENNA ARRAY A combination of antennas with suitable spacing and with all elements excited to make the radiated fields from the individual elements add in the desired direction, i.e., to obtain directional characteristics.

AUTOPILOT A device used to steer a boat automatically, usually electrical, hydraulic or mechanical in nature. A similar mechanism called a self-steering gear may also be used on a sailing vessel.

CHART Maps for boaters are known as charts. Charts are usually issued by government agencies and include information on channels, navigational aids, water depth and hazards.

DEPTH FINDER, DEPTH SOUNDER An instrument used to determine water depth by measuring the time interval for sound waves to go from a source of sound near the surface to the bottom and back again. Also called DEPTH FINDER, ACOUSTIC DEPTH FINDER.

EPIRB Emergency Position Indicating Radio Beacon. An emergency device that uses a radio signal to alert satellites or passing airplanes to a vessel's position.


(Global Maritime Distress
and Safety System)
A system devised by the IMO to improve marine communications, particularly in distress situations. It is designed to automate the process of establishing communication with shore stations such as the Coastguard and with other vessels.

GPS Global Positioning System. A system of satellites that allows one's position to be calculated with great accuracy by the use of an electronic receiver.

HULL SPEED The theoretical speed a boat can travel without planing, based on the shape of its hull. This speed is about 1.34 times the square root of the length of a boat at its waterline. Since most monohull sailboats cannot exceed their hull speed, longer boats are faster.

INSTRUMENTS, INSTRUMENTATION Any type of guage, mechanical or digital, that typically depicts heading, speed, and temperature.

LORAN An electronic instrument using radio waves from various stations to find one's position. The LORAN system is being replaced by the GPS system and will be obsolete in a few years. Many LORAN stations have already stopped providing service.

MONITOR The video display portion of a computer or Electronic Navigation System.

Navigation systems that allow Multiple functions to be displayed on a single screen, i.e. radar displayed with windspeed and direction in separate windows of the display.

NMEA National Marine Electronics Association, an organization that offers Publications and Standards that pertain to the Marine electronics industry.
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OVERLAY A printing or drawing on a transparent or translucent medium at the same scale as a map, chart, etc., to show details not appearing on the original.

PLOT A drawing consisting of lines and points representing certain conditions graphically, as the progress of a craft. See also NAVIGATIONAL PLOT. v.t. To draw lines and points to represent certain conditions graphically, as the various lines and points on a chart or plotting sheet representing the progress of a vessel, a curve of magnetic azimuths vs. time or of altitude vs. time, or a graphical solution of a problem, such as a relative motion solution.

PLOTTER An instrument used for plotting straight lines and measuring angles on a chart or plotting sheet.

RADAR (from radio detection and ranging) A radio system which measures distance and usually direction by a comparison of reference signals with the radio signals reflected or retransmitted from the target whose position is to be determined. Pulse-modulated radar is used for shipboard navigational applications. In this type of radar the distance to the target is determined by measuring the time required for an extremely short burst or pulse of radio-frequency energy to travel to the target and return to its source as a reflected echo. Directional antennas allow determination of the direction of the target echo from the source. 2. As defined by the International Telecommunication Union (ITU) a adiodetermination system based on the comparison of reference signals with radio signals reflected, or re-transmitted, from the position to be determined.

RADOME A dome-shaped structure used to enclose radar apparatus.

An instrument that uses electromagnetic waves to communicate with other vessels. SSB (single sideband) radios have longer ranges than VHF Radios, which are more commonly used.

Video monitors designed to be viewable in even in direct sunlight

TRANSDUCER A device that converts one type of energy to another, such as the part of a depth sounder that changes electrical energy into acoustical energy.

VHF RADIO An instrument that uses electromagnetic waves to communicate with other vessels. VHF (very high frequency) radios are common for marine use, but are limited in range.

WAAS Wide Area Augmentation System, a GPS-based navigation system that offers differential correction which occur from "receiver clock drift" and signal delays by refraction.