INTERNATIONAL ONLY You are on a power driven vessel, maneuvering as authorized, and are in sight of another vessel. You put your engines full speed astern, which statement concerning whistle signals is TRUE?

Correct Answer: Option A — You must sound three short blasts on the whistle.

Under COLREGS Rule 34(a), a power-driven vessel underway in sight of another shall indicate maneuver with whistle signals. When operating astern propulsion, three short blasts must be sounded regardless of whether maneuvering was previously authorized.