What is the purpose of navigation lights on a vessel?

The purpose of navigation lights on a vessel is to indicate the vessel's position, heading, and status to others. These lights play a critical role in maintaining safety during nighttime or low-visibility conditions by communicating information to nearby vessels. For instance, different colors and configurations of these lights can tell other ships whether a vessel is approaching, anchored, or moving in a certain direction. This visual signaling helps prevent collisions and allows for safe navigation in busy waterways or during nighttime operations, thereby enhancing the overall safety of maritime travel.

In contrast to the other options, while illumination on the deck may be aided by certain lights, the primary function of navigation lights is not for deck illumination. Signaling for help in an emergency is typically done through other means, such as distress signals or flares, rather than standard navigation lights. Additionally, navigation lights do not mark the shipping lanes; this task is typically designated for buoys, beacons, or other navigational aids that specifically indicate designated routes within waterways.