What is the arc of visibility for a side light?

Answer: C — 112.5 degrees

The arc of visibility for a side light is correct at 112.5 degrees. This means that the side light is visible to other vessels within an arc of 112.5 degrees from the direction that the light is facing. It is designed to provide visibility and ensure that vessels can identify the orientation and direction of another vessel based on the lights they display. According to the COLREGs, a side light must be shown on each side of a vessel and is intended to be visible from the side and slightly forward, which aligns with the 112.5-degree visibility arc. This specific arc allows other vessels to understand if a vessel is approaching head-on, crossing their path, or if it is stationary. In contrast to other options, such as 180 degrees, which exceeds the intended visibility range for a side light, or 360 degrees, which is the arc of visibility for an all-round light, 112.5 degrees accurately reflects the regulations regarding vessel lighting and ensures safe navigation and collision avoidance.