What is the primary function of navigation lights on a boat?

The primary function of navigation lights on a boat is to signal the boat's presence and direction to other vessels. These lights are essential for safety, particularly during nighttime or in low visibility conditions. By using specific colors and configurations, navigation lights allow other boaters to determine a vessel's orientation, type, and whether it is moving or anchored.

For example, a red light typically indicates the port side of the boat, while a green light indicates the starboard side. A white light at the stern shows the direction the boat is headed. This system of lights helps prevent collisions by improving visibility and aiding in the interpretation of a vessel’s movements and intentions from a distance.

The other options do not accurately reflect the primary purpose of navigation lights. While enhancing the boat's appearance or keeping the crew alert may be side effects, they do not pertain to the critical function of ensuring safety and communication on the water. Indicating the type of boat is also not a primary role, as navigation lights are more about presence and movement rather than classification.