The finished king plank on the keel of our Didi 40 Cr. It is 100 mm wider and 3 mm thicker than the original design and the extra 100 mm with is made from hardwood to spread the keel bolt loads.
I have passed another milestone with the completion of the glassing of the keel floors to the hull. Once that was completed and I cleared all the limber holes I slapped on a coat of epoxy.
While the epoxy was curing I started cutting plywood for the engine compartment and by the time I had the two sides cut the epoxy was cured.
The yacht has been so warm that I have mixed only small batches of epoxy as the pot life is very short in the hot weather. I will paint on a couple of coats of epoxy paint before we launch but I can now get on with building the seats at the ends of the settee that will go over the king plank.
The king plank has been augmented with extra hardwood down both sides to share the pressure from the keel bolts. Dudley’s detail show small packers under the keel bolt washers but I have extended these for the full length of the king plank.
The king plank sits on top of the keel and forms the top of an “I” beam. The keel and plywood skin are the bottom of the beam. The longitudinal beam spreads the forces from the keel bolts among all the floors and in particular spread the loads if the keel touches bottom at speed. The standard design has a 15 mm thick king plank and with our deep keel Dudley increased it to 18 mm thick. With the extra width of timber along the full length of the king plank we have gone from 150 mm by 15 mm to 250 mm by 18 mm and the additional 100 mm is hardwood so the beam is much stronger than the original. The shear stress in bending of the beam is taken by the six massive keel floors which at that point are 110 mm wide and 80 mm deep.