Greetings, there is no traditional double-plank method. The ships were built with single planks only, When the ship was built, it had frames instead of bulkheads used in the ship model kits. To save money, kit manufacturers are using fewest bulkheads to form the hull. It makes it difficult to lay the planks naturally. Therefore kit manufacturers provide double-plank where the first layer is thick planks to form the hull. The modeler can apply filler to those imperfections spots and sand it smooth to make a foundation for the second planks.