How to build an airboat. knowing how to build an airboat requires much research. airboats can be fun to enjoy on the water and those who need a reliable boat for. Airboat. airboat is a mixture of airplane and boat with the thrills of both. it’s a boat powered by an airplane-type propeller with above-the-water rudders that is. Airboat #400 a 13′ swamp boat build in plywood; characteristics; length overall: 12′-9" glen-l marine designs / www.glen-l.com / boat plans for the home builder.