What part of the vessel is described as the upper edge of its side?

The upper edge of a vessel's side is referred to as the gunwale. This term specifically denotes the structural area at the top of the sides of the boat, which provides additional support and can also help prevent water from entering the vessel. The gunwale acts as a boundary for the deck area and is important for securing equipment and creating a safe space on the boat.

On the other hand, a cleat is a fitting used for securing lines, while the beam refers to the width of the boat at its widest point. The hull is the body of the boat that creates the shape and structure below the waterline. Understanding these terms and their specific meanings is crucial for anyone learning about boating and navigation, as they highlight important aspects of vessel design and safety.