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. Kudzu craft canoes are also skin on frame. this is a fun video where the demonstrator pounds and eventually makes a hole in a skin on frame boat.. Ultralight boat building advantages of ultralight boatbuilding. anyone who has tried to move and store a heavy boat, or tried to wrangle a tender onto a yacht deck.