Find a variety of fishing boat design plans for all power boats 16′ long and under. our power boat building plans make it very easy to construct your own!. 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. 24 sailboats. boat plan collection. 24 different and unique boat designs. instant download access! sailboat plans for instant download!.