What is the color of the port side light of a vessel?

Answer: B — Red

The port side light of a vessel is red. According to the International Regulations for Preventing Collisions at Sea (COLREGs), vessels are required to display specific navigation lights to indicate their position and heading to other vessels. The red light indicates the left side (port side) of the vessel when facing forward. This color coding helps mariners easily identify the direction a vessel is heading, which is crucial for safe navigation and to avoid collisions. The red port light, alongside the green starboard light (which is green), forms part of the navigational lighting system that distinguishes the two sides of the vessel. Understanding these color codes is essential for both maintaining safe nautical practices and being compliant with maritime regulations.