What does a green over white light signify?

The green over white light indicates that the vessel is engaged in trawling. This configuration of lights is used specifically to communicate the activity of a fishing vessel that is operating nets or lines while underway at night. It is crucial for other vessels to recognize this signal to maintain safe navigational practices, as trawling may involve obstacles such as nets in the water that can pose a hazard to navigation.

In the context of the other options, a vessel under sail would display specific sail lights, typically green and red for the sidelights. A vessel constrained by draft would display different light signals indicating its restricted ability to maneuver. A vessel towing another vessel uses a different configuration that includes a white light above the towing vessel’s sidelights. Understanding these distinctions helps ensure safe navigation and compliance with maritime signaling regulations.