Waverunner 24. steel or aluminum semi displacement hull boat plans & full size frame patterns see more : coastworker 25 wood epoxy, steel or aluminum, fiberglass. displacement or semi-displacement or planing hull boat plans & full size frame patterns. this is the smallest of our coastworker range that extends from just 25 ft to 58 ft – an ideal first boatbuilding project.. 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 designs that are simple to build, rugged and seaworthy.. Proven boat designs, and how-to information for boat building. boat plans are for beginners and have been built by thousands since 1953..