What lights must be shown on a barge being towed astern at night?

When a barge is being towed astern at night, it is required to display specific lights to ensure its visibility to other vessels and to adhere to the rules governing maritime navigation. The correct answer indicates that sidelights and a sternlight must be shown.

Sidelights are red and green lights positioned on the port (left) and starboard (right) sides of the vessel, making it clear which direction the vessel is facing. The sternlight, which is white, is located at the stern of the vessel, providing indication of the barge's position from behind. Together, these lights help other vessels to ascertain the size, direction, and status of the barge being towed, ensuring safe navigation in the vicinity.

Other options do not fulfill the requirements for nighttime visibility. Simply having a navigation light or only sidelights would not provide sufficient information to other vessels about the vessel's configuration and orientation. An all-around white light alone lacks the directional indicators necessary to inform other boats of the barge's direction of travel, which is critical for maritime safety. Thus, displaying both sidelights and a sternlight is essential for compliance with maritime rules and for ensuring the safety of navigation at night.