What does a vessel displaying green over white lights indicate?

When a vessel displays green over white lights, it indicates that the vessel is engaged in trawling at night. The green light signifies that the vessel is operational and actively fishing, while the white light is an indicator of the activity being performed, specifically that it is trawling, which involves dragging a net behind the vessel in the water. This configuration of lights is part of the International Regulations for Preventing Collisions at Sea (COLREGs), which standardizes marine lighting protocols to help other vessels identify the activities and status of nearby boats.

Understanding the significance of these light configurations is crucial for maintaining safe navigation, especially at night or in low-visibility conditions. Recognizing the green over white light assists other mariners in making informed decisions about their own course and actions to avoid collisions while navigating in proximity to fishing operations.