BOTH INTERNATIONAL & INLAND In a dense fog, you hear a whistle signal of one prolonged blast followed by three short blasts. Which vessel is required to sound this signal?

Correct Answer: Option A — Manned vessel being towed

Rule 35(c) specifies that a vessel being towed, or if more than one vessel is towed, the last vessel of the tow if manned, shall sound one prolonged and three short blasts. This signal identifies the presence of a towed unit to other vessels operating in restricted visibility conditions.