Jeff, Aft edge of centre board case opening is max 3353mm measured from the bow along the centre line of the hull. If the hulls are beamed take care tape measure is straight. Max rake (aft) of centre board is 10degrees. I measure this using a straight edge on top of the two beams, centreboard raised up above the straight edge, measure the angle between the straight edge and the forward edge of the centreboard (usually a straight edge also). I also check the centreboard cannot be swung forward/aft within its case during sailing thus increasing this rake angle.
Phillip Pearce