BOTH INTERNATIONAL & INLAND You are at anchor in fog on a 120 meter power-driven vessel. You hear the fog signal of a vessel approaching off your port bow. Which signal may you sound to warn of your position?

Correct Answer: Option A — One short, one prolonged, and one short blast

COLREGS Rule 35(h) allows a vessel at anchor to sound a signal of one short, one prolonged, and one short blast to give warning of her position and the possibility of collision to an approaching vessel. This is an optional but highly effective safety measure in fog.