INTERNATIONAL ONLY A whistle signal of one prolonged, one short, one prolonged and one short blast, is sounded by which vessel?

Correct Answer: Option A — A vessel being overtaken in a narrow channel

Rule 34(c)(ii) dictates that a vessel being overtaken in a narrow channel or fairway shall, if in agreement, sound the signal of one prolonged, one short, one prolonged, and one short blast. This confirms the overtaking vessel may safely pass the vessel being overtaken in the restricted channel.