How do range lights help a navigator keep a ship on the correct course?

Range lights are a vital tool in coastal navigation, designed to help a navigator maintain a precise course through narrow or hazardous passages, such as channels.12

They function by using two or more lights placed on the shore at different heights and positions. When a ship is on the correct course, the navigator sees these lights aligned in a single vertical plane. If the ship drifts off course, the lights will appear to shift out of alignment, providing an immediate visual cue for the navigator to adjust the vessel's heading to bring the lights back into a vertical line.1

This method relies on the simplicity and reliability of visual navigation, allowing mariners to guide their vessels safely into harbor approaches or through tortuous waters without the need for specialized electronic equipment.2