Which lights does a towing vessel pushing a barge ahead and rigidly connected in a composite unit show?

• A. A vessel at anchor
• B. A sailing vessel with sails set
• C. A towing vessel pushing a barge ahead
• D. A power-driven vessel, not towing

Answer: (D)

When vessels are physically connected and operate as one unit, they are treated as a single vessel for the purpose of lights and signals. A barge that's rigidly connected in front of a tug and pushed ahead forms such a composite unit, so its lights reflect the status of one power-driven vessel underway, not a tug towing another vessel.

That means the unit displays the standard lights for a power-driven vessel underway (sidelights and a stern light, and a masthead light if required by length). There isn’t a separate towing configuration because there isn’t a distinct towed vessel behind the unit.

The other options don’t fit because an anchored vessel would show an anchor light; a sailing vessel with sails set would show sailing-vessel lighting; and a unit that is actually towing would have signals appropriate for towing, not for a single power-driven vessel.