How is a power-driven vessel distinguished from another vessel under 50m?

A power-driven vessel is distinguished from other vessels, particularly those under 50 meters in length, by its lighting configuration, specifically the requirement to display two masthead lights when operating. According to the COLREGs, a power-driven vessel must exhibit these two masthead lights when underway, positioned vertically with one of the lights positioned above the other, which is a clear indication of its operational status and distinguishes it from sailing vessels and other non-power-driven vessels.

This configuration aids in the identification of the vessel type at night or in conditions of reduced visibility, ensuring that other vessels can effectively determine the nature of the vessel they are encountering. The other options do not apply as distinguishing features for power-driven vessels. For instance, additional port lights, sternlight color, and all-around lights may not specifically denote a power-driven vessel's identity as clearly as the two masthead lights do, thus they are not considered the primary distinguishing characteristics under the COLREGs for power-driven vessels.