A centerboard is a retractable keel used in small sailing vessels, such as sailboats. It helps to provide lateral resistance against the sideways force of the wind on the sails, allowing the boat to sail more efficiently. When lowered, the centerboard increases stability and prevents the boat from drifting sideways. Typically made of wood or metal, the centerboard can be raised or lowered through a slot in the hull. This feature allows the boat to navigate shallow waters where a fixed keel would be too deep. The design of the centerboard contributes to the versatility and maneuverability of small sailing crafts.