How is a masthead light configured on a vessel?

The configuration of a masthead light on a vessel is essential for ensuring visibility and safety on the water, especially during nighttime navigation or in reduced visibility conditions. The correct configuration is a white light positioned at the forward part of the vessel that is visible from all sides. This light extends over a 225-degree arc, allowing other vessels to identify the direction that the vessel is facing.

The white masthead light serves to indicate the presence and the orientation of the vessel to others around it, helping to prevent collisions. It's positioned higher than other navigational lights (like sidelights) to ensure it is seen clearly from a distance, especially on larger vessels.

In contrast, the other options represent different types of navigational lights or configurations that do not match the specifications for a masthead light. For instance, red and green lights indicate port (left) and starboard (right) sides of the vessel and do not serve the same purpose as a masthead light. An all-round blue light is used for specific purposes, such as indicating a vessel engaged in fishing, and a red light only at the stern does not provide the necessary visibility from the front, which is critical for safe navigation. Therefore, option A accurately describes the required configuration of a masthead