What are 'Sidelights'?

Sidelights are specifically defined under the International Regulations for Preventing Collisions at Sea (COLREGs) as the red and green lights that are displayed on the sides of a vessel. These lights are situated on the port (red) and starboard (green) sides and are used to indicate a boat's position and direction to other vessels. This visual signaling is crucial for avoiding collisions, especially at night or during periods of reduced visibility.

When a vessel is underway, the sidelights are typically visible from a distance and serve to inform other vessels about which side is which. For example, when two vessels are approaching one another, the position of the sidelights helps each vessel determine the other’s orientation and direction of travel. Seeing the red light on a port side indicates that the other vessel is heading towards them, while the green light on the starboard side shows that the other vessel is on the right side.

This understanding of sidelights is essential for maintaining safe navigation and compliance with the COLREGs. The other options refer to various other types of navigation lights or functions that do not specifically pertain to their defined roles.