What does a vessel towing alongside display at night?

When a vessel is towing another vessel alongside at night, it is required to display specific navigation lights to alert other maritime traffic of its activity. The correct combination of lights is yellow over yellow with a white sternlight.

The yellow over yellow indicates that the vessel is engaged in towing operations, specifically towing another vessel alongside. This is essential for other vessels to recognize the nature of the towing operation, ensuring safe navigation in the vicinity. The additional white sternlight indicates that the vessel is under way and provides further clarity about its position and movement to other navigators.

The chosen combination of lights is standardized under the International Regulations for Preventing Collisions at Sea (COLREGs) to promote safety at night and prevent possible collisions. Understanding these signaling conventions is crucial for operators to ensure their actions are in compliance with maritime regulations and to maintain awareness of their surroundings.