What is required for a vessel over 50 meters when trawling at night?

For a vessel over 50 meters engaged in trawling at night, the requirement for a trawling light is crucial. This light serves to alert other vessels of the trawler's presence and activity, ensuring safety on the water. The trawling light must be positioned to illuminate the area where the nets are deployed and be visible from a significant distance, allowing other mariners to take appropriate navigation measures to avoid collisions.

While the other options, such as a light indicating the vessel's length, harbormaster approval, and navigation radar, play important roles in maritime operations, they are not specific requirements for vessels trawling at night. The primary focus for nighttime trawling safety hinges on the use of the trawling light to maintain visibility and promote safe navigation in shared waterways.