BOTH INTERNATIONAL & INLAND At night you observe a vessel ahead exhibiting three flashes of a white light. What does this signal indicate?

Correct Answer: Option C — The vessel is operating astern propulsion

Rule 34(a) states that a vessel operating astern propulsion shall sound three short blasts. This signal may be supplemented by a light signal of three flashes, which corresponds to the whistle signal, to provide a visual indication of the vessel's maneuver to other vessels in the vicinity at night.