How to make the most out of your one sheet boat. the ultimate one sheet boat, prism: discussion on maximising the displacement. free boat plans and building instructions.. Free 18th century ship plans from chapmannet. the architectura navalis mercatoria by fredrik h. af chapman is available online for free from the chapmannet.the ship plans are superb and is a great reference. this is probably the best collection of 18th century ship plans anywhere.. Free plans: the 13′ rowing dory assay (free downlaodable plans with full-size pattern from classic wooden boat plans); absolutely free plans (links to free online boat plans); ariawood boat works (plywood punts, jonboats and one-sheet boats); architectura navalis mercatoria (high resolution images of the drawings in frederik hendrik af chapman’s book).