Underway motor vessel less than 20 meters, which navigation lights are required?

• A. Stern light, masthead light, and port and starboard side lights
• B. Sidelights only
• C. Masthead light only
• D. All-around white light

Answer: (A)

When a power-driven vessel under 20 meters is underway, you must display the standard set of navigation lights that signal your presence, direction, and status to other ships. This means a white masthead light visible forward, a white stern light at the rear, and red sidelight on the port side with green sidelight on the starboard side. Together, these lights let others know you’re moving and which way you’re heading.

Sidelights alone wouldn’t convey your forward progress, and a masthead light alone wouldn’t show the vessel’s rear aspect. An all-around white light is used in other situations (such as when not underway or while at anchor) and doesn’t meet the full requirement for a vessel underway.