BOTH INTERNATIONAL & INLAND Two power-driven vessels are crossing as shown in illustration D042RR below. Vessel "A" sounds three short blasts on the whistle. What is the meaning of this signal?

Correct Answer: Option D — vessel "A" is backing engines

Under COLREGS Rule 34(a), when power-driven vessels are in sight of one another and meeting or crossing, three short blasts sounded on the whistle specifically indicate that the vessel is operating astern propulsion.