On power-driven vessels, when must navigation lights be on?

Navigation lights on power-driven vessels must be illuminated during periods of restricted visibility, which includes conditions such as fog, rain, or darkness where visibility is significantly limited. This regulation is in place to ensure that vessels can be seen by others, preventing collisions and enhancing overall safety on the water.

In restricted visibility, the use of navigation lights is crucial for signaling a vessel’s presence and intentions to other mariners nearby. While it is advisable to have navigation lights on when docking or during nighttime cruising, the definitive requirement is during periods of restricted visibility, as this encompasses various situations beyond just darkness or fog alone.