Question 580 Rules of the Road

The correct answer is A) It indicates doubt as to the other vessel's action. According to the International Regulations for Preventing Collisions at Sea (COLREGS), the signal of five or more short blasts on the ship's whistle indicates doubt about the other vessel's action or intention. This alerts the other vessel that the signaling vessel is unsure about the other vessel's course of action, and prompts the other vessel to take appropriate measures to avoid a collision. The other answer choices are incorrect because: B) It does not make the other vessel the give-way vessel, C) It does not replace directional signals, and D) It does not necessarily mean the vessel needs to slow or stop.