With respect to positioning of lights, how is 'height above the hull' defined?

The definition of 'height above the hull' is best captured by considering the distance from the waterline to the top of the light. This measurement is crucial for ensuring that the light is visible at the appropriate range for navigation and is consistent with the International Regulations for Preventing Collisions at Sea (COLREGs).

In maritime navigation, the visibility of a vessel's lights plays a significant role in collision avoidance. The waterline is often used as a reference point because it indicates the level at which a vessel floats in the water. Therefore, measuring from the waterline to the top of the light provides a clear and standardized way to assess how high the light is positioned in relation to the immediate water surface, which is critical for ensuring visibility to approaching vessels.

Understanding this definition helps mariners comply with regulations regarding light visibility and positioning, contributing to safe navigation and reducing the risk of collisions at sea.