What is meant by 'computed visibility' in navigation?

• A. Intensity of a lighthouse beam
• B. Visibility of a light
• C. Distance to the horizon
• D. Range of coastal radar

Answer: (B)

Computed visibility refers to the range at which an observer can see or detect a light or object, typically expressed in terms of nautical miles when it pertains to navigation. This concept is crucial for safe navigation, especially in conditions with low visibility due to fog, rain, or other obstructions.

In this context, computed visibility encompasses factors such as the height of the observer's position, atmospheric conditions, and the light's intensity. Understanding computed visibility helps mariners judge whether they will be able to see navigational aids or other vessels, ensuring safer passage.

While the intensity of a lighthouse beam and the distance to the horizon are important in navigation, they do not accurately define computed visibility. The range of coastal radar pertains specifically to radar systems and does not encompass the broader concept of visibility in the navigation context. Therefore, the selection of the visibility of a light as the correct answer aligns with the fundamental definition used in maritime navigation.