What must vessels do in terms of lights during restricted visibility?

In restricted visibility, vessels are required to display appropriate navigation lights to ensure their presence is known to other vessels in the area. This is crucial for safe navigation, as it helps prevent collisions and promotes situational awareness among all mariners. The rules dictate specific light configurations based on the type and size of the vessel, facilitating identification and safe movement in conditions where visibility is limited due to fog, rain, or other obstructions.

Turning off all lights or using only anchor lights could lead to significant safety risks, as nearby vessels may not be able to see the vessel and thus could collide with it. Displaying lights solely according to local regulations might not fulfill the international requirements set forth in the Navigation Rules, which apply to all vessels, regardless of specific local rules. Hence, the requirement to adhere to the appropriate navigation lights during restricted visibility is a critical safety measure to prevent maritime accidents.