Which component is essential for the movement of a boat?

The propeller is essential for the movement of a boat as it generates thrust by converting rotational energy into forward motion. When the engine powers the propeller, the blades push against the water, creating a force that propels the boat forward. This mechanism allows the vessel to navigate through the water effectively.

The other components, while important for different aspects of a boat's function, do not directly contribute to its movement. The beam refers to the width of the boat, affecting stability and capacity, but not movement. A cleat is a fitting used for mooring or securing lines but does not influence propulsion. The gunwale, which is the upper edge of the boat's sides, plays a role in structural integrity and safety but does not aid in generating movement. Understanding the specific functions of these components helps clarify why the propeller is central to the operation of watercraft.