Question 946 Rules of the Road

The correct answer is D) A pilot vessel engaged on pilotage duty. This signal of one prolonged blast followed by four short blasts is the fog signal prescribed in the International Regulations for Preventing Collisions at Sea (COLREGS) for a pilot vessel engaged on pilotage duty. This distinct signal helps alert other vessels in the vicinity of the presence of the pilot vessel, which may be maneuvering or stationary while providing pilotage services. The other options are incorrect because they do not match the specific fog signal described in the question. A vessel being towed, fishing vessels trawling, or a vessel at anchor would have different fog signal requirements under the COLREGS.