Embodiments of the invention are directed to improving parity determination in a data redundancy scheme. In one embodiment, the image layers are arranged in a sequence in which a top 3D image layer is separated from a bottom 3D image layer by a 2D image layer and the image layers are rendered according to the sequence. A surface of a protrusion of the liner abuts the mold so that the surface is exposed and is substantially flush with an exterior surface of the surround after the composite shell is removed from the mold. Wave motion acting on the boat and the frame allow the scrubbers to frictionally contact and clean the boat hull at the waterline.