Relative bearings: points and degrees
1The lesson in plain words
A relative bearing gives an object’s direction from your own bow. Give it in points (11¼° each) or in degrees on the port or starboard bow.
Relative, not compass
A relative bearing is the direction of an object measured from your ship’s head, the direction the bow points. A compass bearing uses north as zero; a relative bearing uses your bow, so you can estimate it by eye. The OOW turns it into a compass bearing or finds the target on radar. STCW lets you report in points or in degrees.
Points
The old compass card has 32 points, so one point is 11¼°. Straight ahead is right ahead; just off it is fine on the bow. Four points (45°) is broad on the bow, eight points (90°) on the beam, twelve points (135°) broad on the quarter, and sixteen points right astern. Count in between: two points on the starboard bow is about 22°; two points abaft (behind) the port beam is about 112° on the port side.
Degrees
You can also give degrees from right ahead, to port or starboard: ‘forty degrees on the starboard bow’. Some ships use the 360° notation, clockwise from the bow: 040 relative is 40° on the starboard bow, and 320 relative is 40° on the port bow. Use the style your ship uses. For three-figure bearings, say each digit: ‘zero four zero’.
Watch the bearing
Watch a light against a fixed part of your ship, such as a window frame. If it moves towards your bow (draws ahead) or stern (draws aft), report the change. If its relative bearing stays the same while your heading is steady, tell the OOW at once: it may indicate collision risk. The OOW assesses the risk under Rule 7.
2Key data
- 1 point
- 11¼° (32 points round the horizon)
- Broad on the bow
- 4 points = 45° from right ahead
- On the beam
- 8 points = 90° from right ahead
- Broad on the quarter
- 12 points = 135° from right ahead
- 360° notation
- 040 relative = 40° on the starboard bow; 320 = 40° on the port bow
- Worked: 3 points on the starboard bow
- 3 × 11¼° = 33¾°, about 34° on the starboard bow
3Key points
- 1
A relative bearing is measured from your own bow, not from north.
- 2
One point is 11¼°: 4 points broad on the bow, 8 on the beam, 12 broad on the quarter.
- 3
In 360° notation: 000° ahead, 090° starboard beam, 180° astern, 270° port beam.
- 4
A relative bearing that does not change while your course is steady: report at once.
4Frequent mistakes
Wrong: ‘Broad on the quarter’ is 45° from right ahead.
Right: Broad on the bow is 45° from right ahead. Broad on the quarter is 45° abaft the beam: 135° from right ahead.
Wrong: A relative bearing is the same as a compass bearing.
Right: It is measured from the bow. When your ship turns, the relative bearing of a fixed object changes; the OOW converts it.
Wrong: A steady relative bearing always means a collision course.
Right: Even with your heading steady, a steady relative bearing does not prove a collision course. Report it promptly; the OOW checks whether the target is closing and assesses the risk.
5Practice case & exam keys
Your ship holds a steady course. You reported a ship’s green light three points on the port bow. Ten minutes later it is still at the same place against the window frame and much brighter. What do you report?
Show the answer
Report at once: ‘Green light, still three points on the port bow, bearing steady, appearing brighter.’ A steady bearing may indicate collision risk, but brightness alone does not prove the target is closing. The OOW checks the range and decides what to do.
Exam keys
- 1 point = 11¼°; broad on the bow 45°, on the beam 90°, broad on the quarter 135°.
- Relative bearings are measured from the ship’s head: to port or starboard, or 000–359 relative.
- Steady relative bearing on a steady course: report at once (possible risk of collision).
Finish this unit
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