BOTH INTERNATIONAL & INLAND In reduced visibility, you hear two prolonged blasts of a whistle. This signal is sounded by which vessel?

Correct Answer: Option B — A power-driven vessel dead in the water

COLREGS Rule 35(b) requires a power-driven vessel underway but stopped and making no way through the water to sound two prolonged blasts at intervals of not more than two minutes. This distinguishes a vessel that is dead in the water from one that is actively making way.