Question 539 Rules of the Road

The correct answer is A) a vessel of special construction. According to the International Regulations for Preventing Collisions at Sea (COLREGS), Rule 21(a), the masthead light on a vessel of special construction or purpose may be located in a position other than the centerline of the vessel. This exception allows for the masthead light to be displaced from the centerline on vessels that, due to their design, cannot have the light positioned at the center. The other options are incorrect because: B) a vessel engaged in trolling is not a relevant exception, C) a power-driven vessel 12 meters in length is required to have the masthead light on the centerline, and D) an air-cushion vessel in non-displacement mode is not a special construction that would allow for a displaced masthead light.