What do the red and green sidelights indicate on a vessel?

The sidelights on a vessel serve a critical function in navigation and safety by indicating the direction a boat is facing. The red light is positioned on the port (left) side, while the green light is located on the starboard (right) side. This color-coding allows other vessels to determine the orientation and movement of a boat, especially at night or in low visibility conditions.

So when you see a red light, it signals that the vessel is approaching from the left, which helps prevent collisions. Conversely, the green sidelights indicate that the vessel is coming from the right side. This system of lights is essential for maritime navigation and understanding the relative positions of vessels on the water. Recognizing these colors aids boaters in making informed decisions, maintaining safe distances, and following the rules of the water.