What type of sailing vessels can combine the side and stern lights in a single lantern?

Sailing vessels of less than 20 meters can combine their side and stern lights in a single lantern due to the navigation lights requirements outlined in the COLREGs (International Regulations for Preventing Collisions at Sea). For smaller vessels, it is often permissible to simplify the lighting arrangement to enhance visibility and ease of use. This combined lantern serves to reduce the number of lights needed, making it more manageable for smaller vessels to adhere to safety regulations while underway.

For larger sailing vessels, specifically those over 20 meters, the regulations require separate and distinct side and stern lights to ensure maximum visibility and clarity for other vessels in the vicinity. This distinction helps prevent confusion about the vessel's orientation and type when observed by other mariners.

Fishing vessels are also subject to specific lighting requirements that pertain to their operations, and while they may have their own variations, the general rule for combining lights specifically applies to sailing vessels under 20 meters in length.