Which type of light is required to indicate a vessel is making way?

A masthead light is required to indicate that a vessel is making way through the water. This is a white light that is positioned on a vessel's fore and is visible from the front and the sides. The visibility of the masthead light serves a critical purpose in the COLREGs by helping other vessels determine the status of the vessel. When a vessel is under way, the masthead light must be illuminated to signify its movement, allowing for safe navigation and the avoidance of collisions.

In the context of the regulatory framework, vessels are required to follow specific lighting rules to ensure their modes of operation can be identified easily. The masthead light's role is especially important because it indicates that the vessel is not only afloat but actively moving through the water, as opposed to being anchored or adrift.

Other types of lights mentioned, such as all-round lights, stern lights, and sidelights, serve different functions and do not specifically indicate that a vessel is making way. For example, all-round lights can indicate the presence of a vessel that is at anchor or using specific operational signals, while sidelights are used primarily to indicate the port and starboard sides of a vessel to others in the vicinity.