A fin keel is a type of keel used in sailing vessels, characterized by its vertical shape and streamlined design. It extends downward from the hull of the boat, providing stability and reducing sideways drift while sailing. The fin keel is typically made of heavy materials like lead or iron, which helps lower the center of gravity and enhances the boat's performance. This design is popular among modern sailing yachts, as it allows for better maneuverability and speed compared to traditional keels. The fin keel is often paired with a rudder, which helps steer the boat effectively, making it a favored choice for competitive sailing and recreational use.