These free to download wooden boat plans (pdf) were first published in magazines such as "popular mechanics", "popular science" and the "boat builder’s handbook".. 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.. Plywood boat plans and wooden canoe plans. sailing dinghy . power . row . paddle . overnight. our plywood boat plans and wooden canoe plans are extremely detailed. click on an image for the page or brief details below.