BOTH INTERNATIONAL & INLAND You are underway in fog and hear one short, one prolonged, and one short blast in succession. What is the meaning of this signal?

Correct Answer: Option D — A vessel is at anchor, warning of her position.

Rule 35(g) authorizes a vessel at anchor to sound a whistle signal consisting of one short, one prolonged, and one short blast to give warning of her position to an approaching vessel. This helps prevent collision by alerting the approaching vessel to the stationary target's exact location.