Full keel
A keel that runs most of the length of the hull, usually with the rudder hung on its trailing edge.
A full keel is the traditional underwater shape: the ballast keel is integral to the hull and runs from near the bow to the stern, and the rudder is attached to its aft edge. The long keel tracks well, protects the rudder and propeller, and takes the ground on its own bottom, which is why it dominates boats sold as offshore cruisers. The price is more wetted surface, a wider turning circle, and awkward handling in reverse under power.
The long fin keel with a cutaway forefoot is the mid-century compromise between a full keel and a fin keel.