Rules of the Road · Light Definitions & Visibility
What arc does a sternlight cover?
- A112.5 degrees centered on dead astern
- B225 degrees from dead astern
- C135 degrees centered on dead astern✓ Correct
- D180 degrees from dead astern
Explanation
Rule 21(c) defines the sternlight as showing a white light over an arc of 135 degrees (67.5 degrees on each side of dead astern). Together with the sidelights' 112.5-degree arcs each, these three lights collectively cover 360 degrees.
Authority: 72 COLREGS Rule 21(c)
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