What does a yellow over white signal indicate?

The yellow over white signal is used to indicate that a vessel is engaged in towing another vessel astern at night. This signal consists of two vertical lights where the top light is yellow and the bottom light is white. It is an important visual cue for mariners to understand the nature of nearby vessels, especially in terms of navigation and possible maneuvers they may need to undertake.

This signaling helps ensure safe navigation by informing other vessels of the towing operation, which can affect maneuverability and how the towing vessel interacts with other traffic. Understanding the meanings of these signals is essential for all mariners to maintain safety on the water.

In contrast, anchoring at night would typically be represented by a different configuration of lights, as would restricted visibility scenarios and vessels using sonar. Hence, the yellow over white signal specifically pertains to a vessel's towing operation at night.