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. Boat plans, boat kits, designers, model builders, building supplies web links for boat plans & boat kits for kayaks, canoes, sailboats, power boats, rowing boats.. Yes, with the right house boat plans, you can start building your own now yes, with house boat plans, you can build a houseboat. when it comes to planning building a.