Freeboard is defined as the distance between which two points?

Freeboard refers to the vertical distance from the waterline to the main deck of a vessel. This measurement is crucial in naval architecture and marine engineering, as it indicates the amount of reserve buoyancy a vessel has above the waterline, which can contribute to stability and safety in various sea conditions. A higher freeboard generally enhances a ship's capability to handle rough waters and reduces the risk of water boarding over the deck.

Understanding freeboard is particularly important for determining potential loading conditions, ensuring compliance with maritime regulations, and improving overall vessel performance and safety. The other choices relate to different aspects of vessel measurement or structure, but they do not define freeboard accurately.