Bruce roberts official web site powerboat plans power boat kits for steel boats or aluminum boat designs, cut to size boat kits, part built boats or complete boats.. Welcome to spira international home-built boat plans. spira international offers a wide variety of different power, rowing, and sailing skiffs, dories, and other boat. All designs for aluminum construction are included here. for further study, we have books available in the books, dvd’s and audio section of our store at your left..