Simrad AP26 and AP27 Autopilots
9 GLOSSARY
Apparent wind – The speed and direction from which the wind appears to blow with reference to the bow when the boat is moving (also called relative wind).
Arrival alarm – An alarm signal issued by a GPS/chartplotter that indicates arrival at or at a predetermined distance from a waypoint. (see arrival circle).
Arrival circle – An artificial boundary placed around the destination waypoint of the present navigation leg, the entering of which will signal an arrival alarm.
Bearing – The horizontal direction of one terrestrial point from another, expressed as the angular distance from a reference direction, usually measured from 000° at the reference direction clockwise through 359°.
BPW – Bearing to a specified waypoint from present position.
BWW – Bearing waypoint to waypoint - Bearing angle of the line between the “TO” and the “FROM” waypoint, calculated at the “FROM” waypoint for any two arbitrary waypoints.
COG - Course Over Ground - The actual direction of progress of a vessel, between two points, with respect to the surface of the earth, The vessel’s heading may differ from the course over ground due to the effects of wind, tide, currents.
GPS - Global Positioning System - This system is based on satellites in fixed orbits, circling the earth at an altitude of approximately 20,200 km. The system will provide the user with 24 hour a day all weather position coverage, with an accuracy of 5 to 30 meters.
Magnetic bearing – Bearing relative to magnetic north; compass bearing corrected for deviation.
Magnetic deviation – A local magnetic field onboard a vessel. Can interfere with the earth’s magnetic field and create compass readings that may deviate from the actual magnetic heading. The deviation will vary with the actual heading.
Magnetic heading – heading relative to magnetic north.
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