Introduction. if you want to have an idea of the workings of a long-gone sailing ship, you need to build a full-size replica, and quite a number of those have been. Free motorboat plans for the backyard home builder, build your own speed boat, cabin cruiser, runabout or utility boat using these simple plywood designs.. This pages shows pictures of eight different submarines and plans of old and new boats. the building of models of the dutch zwaardvis class and walrus class boats is.