Ive just started to put together the forms and strong back for a guillemot L kayak, but have come across a small problem that I dont know the answer to. Ive fixed the forms to the strongback with 8mm space between the first couple of forms and top of the strongback but found that by the last form it is tight ontop of the strongback. The strong back appears straight and square and all forms are lined up by their register marks. Any help would be greatly appreicated.