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 the centerboard is lowered, it increases stability and prevents the boat from being pushed sideways by the wind. When not in use, the centerboard can be raised into the hull of the boat, allowing for easier navigation in shallow waters. This feature makes centerboard-equipped boats versatile and suitable for various sailing conditions, enhancing their maneuverability and performance.