What is an all-round white light used for on power-driven vessels less than 39.4 feet?

An all-round white light on power-driven vessels less than 39.4 feet serves as a critical component of nighttime navigation by acting as a combination of the sternlight and masthead light. This is essential for ensuring that other vessels can see the boat's position and orientation. By using an all-round white light, boat operators can illuminate a full 360-degree area around the vessel, making it visible from any direction.

This light is especially important because it helps define the boat's profile on the water, allowing other vessels to understand the size and heading of the boat, which is crucial for safe navigation and to prevent collisions. While sidelights are also necessary for other vessels, the all-round white light effectively consolidates the functions of both the masthead light, which shows the front/forward aspect of the vessel, and the sternlight, which represents the rear, thereby ensuring optimal visibility without the need for additional lighting.

In terms of nighttime usage, this all-round light is mandatory when other navigation lights are required, which means it serves a broader purpose than simply being "only used at night." It does not indicate distress; signals for distress are characterized by specific configurations not related to standard navigation lighting. Lastly, while it can contribute to a vessel