What is the vertical level of water on the hull of a ship known as?

The vertical level of water on the hull of a ship is referred to as the waterline. This is the line that indicates where the surface of the water meets the ship’s hull when the vessel is floating in water, and it varies with the weight of the ship and the water conditions. Understanding the waterline is vital for ship design and stability, as it helps determine the ship's load capacity and buoyancy. The waterline is a critical reference point in naval architecture and maritime operations.

The other terms mentioned have specific meanings that are related to ship construction and operation but do not define the water's vertical level on a ship's hull. Beam refers to the width of the ship at its widest point. Freeboard is the distance from the waterline to the deck level, indicating how much of the hull is above the water; while hull simply describes the body of the ship itself, focusing on its structural aspects rather than its interaction with water levels.