If your tug is pushing a barge ahead at night and it is not a composite unit, which light(s) should show aft on your vessel?

When a tug is pushing a barge ahead at night and is not considered a composite unit, it must display the appropriate lights as per maritime navigation rules. A tug that is pushing a barge is required to exhibit one towing light above the stern of the tug and, in this case, it would also need to show two towing lights to indicate that it is engaged in tow operations.

The two towing lights displayed would typically consist of one light positioned at the centerline of the tug and another positioned at each of the outer sides, effectively providing a clear visual signal of the tug's operational status. This is crucial for other vessels to recognize that a tow is in progress and to ensure safe navigation, especially in the dark.

In contrast, a vessel that is not actively engaged in towing would not need to display these lights. Furthermore, a sternlight is not sufficient alone to convey the nature of the operation, as it only signifies a vessel's position rather than its engagement in a towing operation. The requirements for lights are stipulated in the International Navigation Rules (COLREGs), which state that a tug that is pushing must ensure that its lighting configuration clearly indicates its status to other vessels.