Question 693 Rules of the Road

The correct answer is D) three black balls in a vertical line. This is the correct answer because according to the International Regulations for Preventing Collisions at Sea (COLREGS), a vessel 30 meters or more in length when aground must display three black balls in a vertical line. This signal indicates that the vessel is aground and unable to maneuver. The other answer choices are incorrect because a cylinder is the shape for a vessel at anchor, two black balls indicate a vessel restricted in its ability to maneuver, and a single black ball is the shape for a vessel not under command.