What term refers to the distance between the waterline and the upper deck of a ship?

The term that refers to the distance between the waterline and the upper deck of a ship is known as "freeboard." Freeboard is a critical measurement in naval architecture and ship design, as it indicates the reserve buoyancy of a vessel. Essentially, it represents how much of the ship's structure is above the waterline, providing insight into the ship's stability and seaworthiness. A greater freeboard means the ship is less likely to take on water in rough seas, thus enhancing safety and performance.

In contrast, the draft measures how deep the ship sits in the water, from the waterline to the bottom of the hull, and the keel is the underlying structure along the bottom of the ship. The term "fantail" refers to a particular design feature at the stern of a ship, often a deck or overhang. Understanding these terminologies is crucial for anyone working in marine and maritime fields, as they directly impact vessel operation and safety.