According to the Rules, which vessel MUST show two masthead lights in a vertical line?

According to the Rules, which vessel MUST show two masthead lights in a vertical line?

• A. A sailing vessel under sail only
• B. A vessel not under command
• C. A power-driven vessel less than 50 meters in length with a 20-meter tow
• D. A fishing vessel with gear deployed

Answer: (C)

Two masthead lights in a vertical line identify a power-driven vessel when underway, and the rule sets a length threshold: a vessel 50 meters or longer must display two white masthead lights one above the other. If the vessel is towing, the total length to consider can include the tow, so the towing vessel must also show two masthead lights if that combined length meets the threshold. In this scenario, the vessel is power-driven and has a 20-meter tow, making the overall length at least 60 meters. That meets the requirement, so it must display two white masthead lights in a vertical line. The other situations don’t fit this lighting rule: a sailing vessel under sail alone isn’t governed by the masthead-light requirement for power-driven vessels; a vessel not under command uses different red lights to indicate inability to maneuver; a fishing vessel with gear deployed has its own specific lighting scheme that doesn’t call for two masthead lights in a vertical line.

Two masthead lights in a vertical line identify a power-driven vessel when underway, and the rule sets a length threshold: a vessel 50 meters or longer must display two white masthead lights one above the other. If the vessel is towing, the total length to consider can include the tow, so the towing vessel must also show two masthead lights if that combined length meets the threshold.

In this scenario, the vessel is power-driven and has a 20-meter tow, making the overall length at least 60 meters. That meets the requirement, so it must display two white masthead lights in a vertical line.

The other situations don’t fit this lighting rule: a sailing vessel under sail alone isn’t governed by the masthead-light requirement for power-driven vessels; a vessel not under command uses different red lights to indicate inability to maneuver; a fishing vessel with gear deployed has its own specific lighting scheme that doesn’t call for two masthead lights in a vertical line.