That second plank you found broken looks like the keystone to the structure. It seems a bit thin in design there, eh? I suppose the some of the outer drifts carry the torque through to the leading edge of the third plank.

Well it worked for how long now? 50 years for any rudder seems very good. All the parts were capable of many years immersed in water. What will be the life span of composite rudders? If, when water gets inside, it will cause problems.

How was the fit of the bolts through the rudder stock Paul? Mine were a little loose so I went up one size on all the bronze and redrilled for a snug fit in the rudder stock. Luckily I had plenty of bronze stock, and the mahogany was like new.

Thanks for taking the time to post your rebuild, it'll be fun to follow.