What lights does a vessel not under command, underway but not making way, show?

• A. One white light
• B. Two all-round white lights
• C. Two all-round red lights in a vertical line
• D. Red over white light

Answer: (C)

When a vessel is not under command, it cannot maneuver to avoid other vessels. To warn others of this inability to steer, it must display two all-round red lights in a vertical line. These red lights indicate danger and the lack of maneuverability, making other vessels take early and wide action to avoid a collision. The two red lights are visible in all directions, signaling the vessel’s condition regardless of its heading.

The other options don’t represent this status: a single white light isn’t the required signal for not under command, two white lights don’t convey the same restricted maneuver condition, and a red over white light is used for a different signaling situation and does not indicate not under command.