A white masthead light shows through an arc of how many degrees?

A white masthead light shows through an arc of how many degrees?

• A. 360°
• B. 180°
• C. 225°
• D. 270°

Answer: (C)

Think about how nav lights are arranged to convey direction and position. The white masthead light is a forward-facing light that must be visible over a 225-degree arc. This lets other vessels see you from ahead and broad to the sides, while the rear sector is covered by the stern light. In other words, the masthead light doesn’t illuminate directly behind you, but it covers most of the forward hemisphere, specifically 225 degrees. The remaining rear sector is lit by the stern light, and the sidelights complement to give full 360-degree visibility when all lights are used. That’s why the arc for the masthead light is 225 degrees.

Think about how nav lights are arranged to convey direction and position. The white masthead light is a forward-facing light that must be visible over a 225-degree arc. This lets other vessels see you from ahead and broad to the sides, while the rear sector is covered by the stern light. In other words, the masthead light doesn’t illuminate directly behind you, but it covers most of the forward hemisphere, specifically 225 degrees. The remaining rear sector is lit by the stern light, and the sidelights complement to give full 360-degree visibility when all lights are used. That’s why the arc for the masthead light is 225 degrees.