The white masthead light required for a power-driven vessel is visible over how many degrees of the horizon?

For a power-driven vessel, the white masthead light is designed to be visible over 225 degrees of the horizon. This specification ensures that the light can be seen from a wide angle, allowing other vessels and observers to detect the presence of the power-driven craft from various directions. The light must be positioned in such a way that it is visible to oncoming vessels approaching from the front and sides, which is critical for navigational safety.

The 225-degree visibility requirement stems from maritime regulations that prioritize safety; specifically, it helps indicate the direction the vessel is heading while minimizing confusion with other lights. The light will shine from straight ahead of the vessel to approximately 22.5 degrees abaft (behind) the beam on either side, effectively covering this 225-degree arc.

While there are other configurations for different types of vessels, such as sailing vessels that might have variations in their light visibility, for power-driven vessels, the 225 degrees specification is the standard to follow. This specific angle balances visibility with the need to design a light that can be identified easily by other vessels, thereby promoting safe navigation on the water.