What is the upper edge of a vessel's side called?

The upper edge of a vessel's side is referred to as the gunwale. This term is important for understanding the structure of a boat, as the gunwale serves several purposes. It helps to provide rigidity to the hull and acts as a barrier that helps keep water from entering the boat. Additionally, the gunwale often serves as a convenient place to attach equipment or perform tasks such as tying off lines.

Recognizing this feature is vital for safe boating practices, as it can indicate where to safely handle and maneuver around the edges of the vessel. Other terms that might come to mind include the hull, which refers to the entire structure of the boat excluding the deck, the freeboard which refers to the distance from the waterline to the upper deck level, and the beam, which indicates the width of the vessel. However, none of these terms specifically denote the upper edge of the vessel's side, making gunwale the precise and correct answer.