BOTH INTERNATIONAL & INLAND The arc of visibility for sidelights is from right ahead to what degree?

Correct Answer: Option D — 22.5° abaft the beam

Rule 21(b) defines the arc of visibility for sidelights as 112.5 degrees. This arc extends from right ahead to 22.5 degrees abaft the beam on either side of the vessel. This specific geometry ensures that a vessel's aspect is clearly communicated to other mariners during night navigation.