Knowledge Base
galley
The kitchen area of a boat.

gangway
The area of a ship’s side where people board and disembark.

gear
A general term for ropes, blocks, tackle and other equipment.

geoid
A surface along which the gravity potential is everywhere equal (equipotential surface) and to which the direction of gravity is always perpendicular.

geometric dilution of precision
(GDOP)A value representing all geometric factors that degrade the accuracy of a position fix which has been derived GDOP

give-way vessel
A term used to describe the vessel that must yield in meeting, crossing, or overtaking situations.

Global Navigation Satellite System
(GNSS) Any single or combined satellite navigation system. Currently the options are: GPS, GLONASS, and combined GPS/GLONASS.

Global Positioning System
GPS is defined as the constellation of satellites, the navigation payloads which produce the GPS signals, ground Global positioning system (GPS)

GNSS
Global Navigation Satellite System. Any single or combined satellite navigation system. Currently the options are: GPS, GLONASS, and combined GPS/GLONASS.

GPS
Global Positioning System is defined as the constellation of satellites, the navigation payloads which produce the GPS signals, ground GLONASS

grab rails
Hand-hold fittings mounted on cabin tops and sides for personal safety when moving around the boat.

great circle
The intersection of the surface of a sphere and a plane through its center.

great circle chart
A chart on which a great circle appears approximately as a straight line.

great circle direction
Horizontal direction of a great circle, expressed as angular distance from a reference direction.

GRI
Group Repetition Interval. Of a particular Loran-C chain, the specified time interval for all stations of the chain to transmit their pulse groups. For each chain a minimum group repetition interval is selected of sufficient duration to provide time for each station to transmit its pulse group and additional time between each pulse group so that signals from the two or more stations cannot overlap in time anywhere within the coverage area.

ground tackle
A collective term for the anchor and its associated gear.

group repetition interval
(GRI) Of a particular Loran-C chain, the specified time interval for all stations of the chain to transmit their pulse groups. For each chain a minimum group repetition interval is selected of sufficient duration to provide time for each station to transmit its pulse group and additional time between each pulse group so that signals from the two or more stations cannot overlap in time anywhere within the coverage area.

gunwale
The upper edge of a boat’s sides.

gyrocompass
A compass having one or more gyroscopes as the directive element, and which is north-seeking. Its operation depends upon four natural phenomena: gyroscopic inertia, gyroscopic precession, the earth’s rotation, and gravity.

gyropilot
An automatic device for steering a vessel by means of control signals received from a gyrocompass (see Autopilot).

gyroscope
A rapidly rotating mass free to move about one or both axes perpendicular to the axis of rotation and to each other.

 
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