What is the purpose of the sternlight on a vessel?

The purpose of the sternlight on a vessel is primarily to illuminate the aft (the rear portion) of the boat. This light is essential for visibility, especially during nighttime navigation or in low-light conditions. It helps other vessels identify the position and orientation of your boat from behind, allowing them to determine that the vessel is moving away from them or what direction it is heading based on the positioning of the light.

The sternlight is required by maritime regulations to ensure safety on the water, as it provides crucial information to other mariners about your vessel's location and navigational status. This facilitates safe navigation and helps prevent collisions by ensuring that vessels can see and identify each other, particularly at night or in poor visibility conditions.