These three components need to be very accurately machined and aligned, as they define the fore and aft curvature along the bottom of the boat. I used the same technique that I used to make the formers to get precise curves. However, because I do not want to spoil the final appearance with nail hole marks, I first made MDF templates, and then, having rough cut the plywood, I used a bearing guided straight router cutter to trim the ply to the templates. When I machined the sides of the centreboard case, I clamped them together, and drilled a 4 mm hole at each corner, where the holes will be eventually be concealed by capping, as well as a 2 mm hole to define the centreboard pivot. I then clamped the fore and aft spacers to one side, and used the router to shape the spacers, through which I drilled matching 4 mm holes. As I assemble the centreboard case, I will insert 4 mm diameter stainless steel pins through the holes to ensure that the sides exactly align, as shown in the photos below.
The centreboard case and fore and aft girders
