About our free boat plans: the free boat plans listed here are public domain plans. we have put them together into a more usable format than most free boat plans. Free motorboat plans for the backyard home builder, build your own speed boat, cabin cruiser, runabout or utility boat using these simple plywood designs.. Learn how to build yourself a houseboat in your backyard. our complete boat plans collection is available for free and immediate download. it is the largest wood boat.