Variable hull lengths for watercraft

A watercraft comprising:

• a hull having a bottom surface and a stern;
• and
• buoyant bodies adjustably attached to a rear surface of the stern, the buoyant bodies forming a U-shape with the stern and defining a rearwardly opening space therebetween, wherein each buoyant body includes:
• a bottom planing surface, substantially parallel front and rear walls, and port and starboard sides extending between the front and rear walls,
• a stair step on the bottom planing surface of the buoyant body, the stair step extending laterally between the port and starboard sides and substantially parallel to the stern, the stair step dividing the bottom planing surface in a forward planing surface and a rear planing surface, the forward planing surface and the rear planing surface disposed in substantially different planes,
• the forward planing surface and the rear planing surface being higher than the bottom surface of the hull, the entire rear planing surface being higher than the forward planing surface,
• wherein the buoyant bodies are each arranged to be vertically adjusted by a lifting device to vary static lift and dynamic lift on the buoyant bodies.