When must navigation lights be displayed on a vessel?

Displaying navigation lights on a vessel is a crucial safety practice that is specifically mandated to enhance visibility and prevent collisions. The correct answer indicates that navigation lights must be illuminated from sunset to sunrise and also when visibility is restricted due to conditions such as fog, rain, or other environmental factors.

During nighttime, the absence of natural light can make it very difficult for boats to see each other. Navigation lights provide essential information about a vessel's position, direction, and type, allowing operators to make informed decisions to avoid accidents. Additionally, limited visibility conditions can hinder a boat's ability to see oncoming traffic, making navigation lights even more critical in these circumstances.

While there may be rules about lighting during the day, such as using sidelights in certain situations or in densely populated boating areas, the overarching guideline remains that navigation lights are required whenever visibility is poor or absent. This ensures not only the safety of the vessel displaying the lights but also that of others on the water.