Bouyant hull extension providing lateral and longitudinal control for lightweight hulls

A buoyant stern mounted hull extension for a watercraft that is comprised of two buoyant, sealed sponsons that are attached or formed as rigid extensions of a stern of said watercraft, one of said sponsons being attached or integrally formed as an extension on a port side of said stern, astern of a propulsion system mounting transom, and the other of said sponsons being attached or integrally formed as an extension on a starboard side of said stern, astern of said transom, said sponsons having outer wall surfaces that match a shape of a parent hull at an attachment point, said sponsons being separated by a longitudinal well that is open to an aft end of said watercraft and is closed off amidships, said sponsons forming parallel vertical surfaces that extend longitudinally on either side of said well, said well being wide enough to allow amidships placement of an inboard or outboard propulsion device at an interior amidships transom formed between said sponsons, said sponsons provide buoyant support equal to or greater than the weight of the propulsion system and other fixed hardware installed in or on the rear section of the boat, said well may be long enough to protect the outdrive in raised horizontal position, said well may be narrow enough to restrict the size of the propulsion device, where bottom surfaces of said sponsons extend planing surfaces of the hull in the same plane astern of said amidships transom to form an extension of a planing pad of said hull, said planing pad on an underside of said sponsons intersecting at right angles to lower interior surfaces of said well to form interior hard chines.