Before I started the rudders I marked where the rudder lashings would fall on the sterns. And then chiseled out the wood where the lashings would pass through and filled with thickened epoxy. The lashings were the entry points for water on the original hulls and I didn’t want to have that problem again.
Building the rudders should have been straight forward! But I made a mistake and had to cut the rudders twice :) I pointed the rudder heads the wrong way - just turned the template around. When I was back on track, I chiseled out the wood at the rudder lashings and filled with thickened epoxy. Then I fiberglassed the rudders in two passes. One side and then the other with overlaps along the edges. I tried to make the overlaps neater by using masking tape to make a clean edge. It worked well.