You are approaching another vessel at night. You can see both red and green sidelights and, above the level of the sidelights, three white lights in a vertical line. The vessel may be towing a tow more than 200 meters astern.

• A. Yes
• B. No
• C. It is anchored
• D. It is a sailing vessel

Answer: (A)

Three white lights in a vertical line above the sidelights signal a towing situation. When a vessel is towing another vessel and the tow is more than 200 meters long, additional white lights are displayed in a vertical stack above the regular lights. Seeing red and green sidelights confirms the vessel is underway, not anchored, and the three white lights indicate a long tow behind. So you’re indeed encountering a vessel that may be towing a tow more than 200 meters astern.

The other options don’t fit this light pattern: anchoring would not show this vertical stack of white lights, and a sailing vessel isn’t defined by three white lights in a column.