Question 441 Rules of the Road

The correct answer is D) A vessel constrained by her draft. According to the International Regulations for Preventing Collisions at Sea (COLREGS), a vessel constrained by her draft is not permitted to exhibit two red lights in a vertical line. This is because the two red lights in a vertical line is the signal used to indicate a vessel aground, not a vessel constrained by draft. The other options (A, B, and C) are incorrect because a vessel aground, a trawler fishing in close proximity to other trawlers, and a dredge are all permitted to exhibit two red lights in a vertical line to indicate their status.