United States Coast Guard Captains License Practice Exam 2025 – Comprehensive All-in-One Guide for Exam Success!

A barge being towed astern at night must display sidelights and a sternlight to meet the navigation rules established for vessels in these situations. Sidelights consist of a red light on the port (left) side and a green light on the starboard (right) side to indicate the barge's position and heading. The sternlight, which is a white light positioned at the rear of the vessel, provides visibility from behind, indicating that the barge is part of a tow and should not be confused with a vessel underway by itself.

This combination of lights ensures that other vessels can easily identify the barge and its relationship to the tow, which is crucial for safe navigation. Displaying only sidelights without a sternlight or just a single all-round white light would not provide adequate indication of the barge's position or the nature of the tow, which could potentially lead to dangerous situations on the water.