What is the term for the maximum width of a vessel?

The term for the maximum width of a vessel is known as the beam. This measurement is critical in determining a vessel's stability and handling characteristics. A wider beam generally provides better stability, allowing the vessel to distribute weight more evenly and resist tipping in rough waters.

Understanding the context of other terms helps clarify why beam is the correct answer. Draft refers to the vertical distance between the waterline and the bottom of the hull, which indicates how much of the vessel is submerged. The keel is the structural component that runs along the bottom of the hull, contributing to the vessel's structural integrity and sometimes its stability. Freeboard refers to the distance from the waterline to the upper deck level, essentially measuring how much of the vessel is above water. Each of these terms pertains to different aspects of a vessel's design and functionality, but the width specifically is captured by the term beam.