BOTH INTERNATIONAL & INLAND The stern light shall be positioned such that it will show from dead astern to how many degrees on each side of the stern of the vessel?

Correct Answer: Option B — 67.5°

Rule 21(c) defines the stern light as a white light placed as nearly as practicable at the stern, showing an unbroken light over an arc of 135 degrees. This arc is centered on the stern, extending 67.5 degrees to port and 67.5 degrees to starboard, totaling 135 degrees.