A watercraft support platform casing for a floating dry dock for light weight watercrafts is described. The support platform casing has integrally formed floatation chambers and an elongated central ramp is formed in the top surface of the casing to support the hull of a watercraft positioned thereon. The ramp has a trough-like upper surface with a sloped forward entry way formed integral therewith and terminates in a lower forward projecting edge. The support platform is provided with connectors on opposed side walls thereof for a rigid connection with a plurality of floatation casings to support the platform casing on a water surface with the entry way positioned to receive the bow of a watercraft in movement whereby the watercraft can project itself on the central ramp above the water surface.