All power boats 16′ long and under. tech support. the best technical support: we will help you succeed! all our plans and kits come with full technical support.. 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. 24 sailboats. boat plan collection. 24 different and unique boat designs. instant download access! sailboat plans for instant download! have you ever wanted to build a sailboat?.