This composite pontoon catamaran is versatile, so you can build the boat to fit your specifications. order the plan and the cat 20 kit at bateau.. Specmar aluminum catamaran hulls are either symmetrical or asymmetrical in design. a symmetrical hull consists of two basic v-bottom hull structures.. Manufacturer of shallow water, catamaran flats boat with hand laminated fiberglass hull, patented catamaran design, and self bailing. located in rosenberg, texas..