Design, computer lofting, and kits for welded aluminum boats. specmar inc (previously specialty marine contractors) is an aluminum boat design, lofting, and kit company.. Designs available in aluminum…. aluminum is also a superb material for boatbuilding by the person qualified in aluminum welding. aluminum boats using welded marine. Alumaweld’s stryker sport is the most popular heavy gauge welded aluminum boat ever! the established benchmark of boating value, the stryker is available in 18′ and.