What is the primary purpose of navigation lights on a ship?

The primary purpose of navigation lights on a ship is for safe navigation. These lights are crucial for ensuring that vessels can be identified and their direction of travel recognized, especially at night or in reduced visibility conditions. Each type of navigation light has a specific function; for instance, red and green sidelights indicate the direction a vessel is heading, while a white stern light signifies the rear of the vessel. By displaying these lights, ships can avoid collisions and navigate safely through busy waterways, which is essential for maintaining maritime safety.

While speed indication and communication with other ships are important aspects of maritime operation, they do not pertain to the primary function of navigation lights. Similarly, while navigation lights do enhance visibility in the dark, their main purpose revolves around the safe identification of vessels and their movements, rather than daytime visibility enhancement.