Relative bearing
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In nautical navigation the relative bearing of an object is the angle formed by the heading of the vessel and a straight line drawn from the observer on the vessel to the object.
The relative bearing is measured with a pelorus.
The measurement of relative bearings of fixed landmarks and other navigation aids is useful for the navigator because this information can be used on the nautical chart together with simple geometrical techniques to aid in determining the position of the vessel and/or its speed, course, etc.
The measurement of relative bearings of other vessels and objects in movement is useful to the navigator in avoiding the danger of collision.
- Example: The navigator on a ship observes a lighthouse when its relative bearing is 45º and again when it is 90º. he now knows that the distance from the ship to the lighthouse is equal to the distance trvelled by the vessel between both observations.
