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

The primary purpose of navigation lights on a boat is indeed to indicate the boat's position to others. These lights serve a crucial safety function, especially during nighttime or low-visibility conditions. By using specific colors and configurations, navigation lights help other vessels determine the size, direction, and status of a boat. For example, a red light on the port (left) side and a green light on the starboard (right) side indicate the boat's orientation and heading. This allows mariners to navigate safely, avoid collisions, and ensure everyone on the water can see each other's locations and movements clearly.

The other options highlight activities that don't align with the primary function of navigation lights. Attracting fish is typically accomplished through other means, and signaling speed is managed through other forms of communication. Illuminating the deck is also not the main intent of navigation lights; rather, it relates to onboard lighting for visibility and safety purposes.