What are the requirements for the vertical sectors and minimum intensity of navigational lights on a power-driven vessel?

The correct answer highlights that navigational lights on a power-driven vessel must adhere to the specifications set forth by the COLREGs (International Regulations for Preventing Collisions at Sea). These regulations specify not only the color and position of the lights but also the vertical sectors they illuminate and their minimum intensity.

COLREGs outline that the vertical sectors of navigational lights should be designed to ensure that the lights are visible from the appropriate angles and distances, providing the necessary visibility to other vessels and helping to prevent collisions. This is crucial for safe navigation, especially in crowded or restricted waters. The regulations also dictate the minimum intensity of these lights to ensure they can be seen clearly by other vessels under various visibility conditions.

This adherence to the COLREGs ensures uniformity in maritime navigation standards globally, promoting safety and preventing misunderstanding among vessels of differing nationalities. Therefore, following these specific guidelines protects both the vessel's crew and other mariners by enabling them to ascertain the type and direction of approaching vessels.