What does a sailing vessel of less than 20 meters combine regarding navigation lights?

A sailing vessel of less than 20 meters in length is permitted to combine its sidelights and sternlight into a single lantern, which simplifies the lighting requirements for smaller vessels. This combination aids in reducing the number of lights required on such vessels, making them easier to manage while still complying with the COLREGs regulations.

The combination of sidelights (green for starboard and red for port) and a stern light into one unit allows for a clear signal to other vessels of the sailing vessel's presence and direction, enhancing visibility and safety on the water. This is particularly useful for smaller vessels that might not have the space or resources to install multiple individual lights. The other options do not accurately represent the lighting requirements set forth in the COLREGs for this size of vessel.