In nautical navigation the relative bearing of an object is the
clockwise angle from the heading of the vessel to a straight line
drawn from the observation station on the vessel to the object.
The relative bearing is measured with a pelorus or other optical and
electronic aids to navigation such as a periscope, sonar system, and
radar systems. Since World War II, relative bearings of such diverse
point sources have been and are calibrated carefully to one another.
United States Navy
Example: The navigator on a ship observes a lighthouse when its relative bearing is 45° and again when it is 90°. He now knows that the distance from the ship to the lighthouse is equal to the distance travelled by the vessel between both observations.
Absolute bearing Bearing
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