What is the arc of visibility for a side light?

The arc of visibility for a side light is 112.5 degrees, which is designed to provide effective illumination for other vessels to recognize the presence and orientation of a boat. According to the COLREGs, side lights are positioned on the port (left) and starboard (right) sides of a vessel, and they are visible from the front quarter on their respective sides, contributing to safety during navigation.

This 112.5-degree arc ensures that the light can be seen clearly to the other vessels approaching from the side, while also taking into account the need for the light to be less visible from directly behind the vessel, indicating that the vessel is moving forward. The limited visibility helps reduce confusion about the direction and intention of the vessel.