The three types of keels are the full, fin, and wing. The full keel is the most common and it is what most people think of when they picture a keel. It extends from the bow to the stern and provides lift and stability. The fin keel is narrower and located near the centerline of the boat. It is more efficient at lifting the hull out of the water but can make the boat less stable. The wing keel is similar to a fin keel but has wings that extend out from either side to provide even more lift.