What is a key requirement for a vessel less than 12 meters when displaying lights?

A key requirement for a vessel less than 12 meters in length is the ability to display combined sidelights. Combined sidelights serve as a practical solution for smaller vessels, as they simplify the lighting requirements while ensuring compliance with navigation rules. These sidelights typically feature a green light on the starboard side and a red light on the port side, which allows for the proper indication of the vessel's direction and enhances visibility to other boats.

The use of combined sidelights helps maintain safety on the water, especially during nighttime operations or in low visibility conditions. This requirement reflects the understanding that smaller vessels often have limited space for mounting separate lighting fixtures and can still effectively communicate their position and movement on the water with this combined lighting setup.