In maritime navigation, the precise measurement of angles between the observer, objects, and reference points is crucial for safe and effective maneuvering. This blog post explains the key concepts of bearings and their applications in navigation.
What is a Bearing?
The term ‘bearing of an object’ refers to the angle formed between the direction of the north and the imaginary line connecting the observer to the object. Bearings are fundamental in determining the relative positions of objects in navigation.
Relative Bearing
The term ‘relative bearing’ defines the angle formed between the direction of a vessel’s bow and the imaginary line connecting the observer to the object. This measurement is critical for understanding the relative positioning of surrounding objects from the perspective of the vessel.
Types of Bearings
Based on the reference point used for measurement, bearings are categorized into three types:
- True Bearing
- Magnetic Bearing
- Compass Bearing
True Bearings
True bearings are measured in degrees clockwise (holocyclic) from 000° (true north) to 360°. This system provides a standardized reference for all navigational calculations.
Magnetic Bearings
Magnetic bearings use the magnetic north as the reference point. The angle is measured similarly to true bearings but is affected by the magnetic variation between true north and magnetic north.
Compass Bearings
Compass bearings are derived from the ship’s compass and include corrections for both magnetic variation and compass error (deviation).
Measuring Relative Bearings
Relative bearings are measured in degrees from 000° to 360°, either to the right or to the left of the bow. These are further characterized as:
- Right (Green): Bearings measured clockwise from the bow.
- Left (Red): Bearings measured counterclockwise from the bow.
This distinction aids mariners in quickly identifying the relative position of objects concerning the vessel’s heading.