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 fishing or other water. Airboat #400 a 13′ swamp boat build in plywood; characteristics; length overall: 12′-9" beam: designed for use with glen-l series 650 boat trailer plans. photographs. Complete material listing and step-by-step instructions take you through building the hull and explain in detail all of the engine airboat plans & patterns plus.