Keel types refer to the different designs of the keel, which is the structural backbone of a boat or ship. The keel helps to provide stability and balance, allowing the vessel to sail efficiently. Common keel types include the fin keel, which is a vertical blade that extends downward, and the full keel, which runs along the entire length of the hull for better stability. Another type is the bulb keel, which features a bulbous shape at the bottom to lower the center of gravity, enhancing stability. The centerboard is a retractable keel that allows for shallow water navigation, making it ideal for smaller boats. Each keel type serves specific purposes based on the vessel's design and intended use.