Design, computer lofting, and kits for welded aluminum boats. specmar inc (previously specialty marine contractors) is an aluminum boat design, lofting, and kit company.. Boat design and boatbuilding projects, plans, concepts, reviews, and resources. sailboat, multihull, powerboat, and yacht manufacturers and custom builders. directory. Clark craft offers hundreds of boat plans, design patterns and complete boat kits, and a full line of boat building supplies and accessories for the amateur boatbuilder..