What is the purpose of a sternlight on a vessel?

The purpose of a sternlight on a vessel is to provide visibility and indicate the position of the vessel from behind. It is typically placed at the stern and emits a white light that is visible from the rear of the craft. This is important for navigation and safety, especially at night or in low-visibility conditions, as it allows other vessels approaching from the rear to see that a vessel is there and understand its direction of travel.

Sternlights are crucial for preventing collisions by ensuring that boats can be clearly identified from behind, where they might otherwise be difficult to see. The light's specific positioning and color help to communicate the presence and movement of the vessel to those who may be approaching from that angle.