For motor vessel underway greater than or equal to 20 meters and less than 50 meters, which lights are required?

• A. Stern light, sidelights, and stern light
• B. All-round white light
• C. Masthead light, stern light, and sidelights
• D. Stern light, masthead light, and port and starboard side lights

Answer: (D)

A motor vessel underway in the 20–50 meter range must show the white masthead light forward, a white stern light, and the red and green sidelights on the port and starboard sides. This combination lets other vessels determine your direction and that you’re making way at night: the masthead light marks your forward direction, the stern light marks your rear, and the sidelights signal which side is which as they view you from different angles.

All-round white light alone would not convey your orientation and status in this situation, and one option that repeats the stern light isn’t a valid light configuration. The precise requirement is the masthead light, the stern light, and the port and starboard side lights.