And in fact it was again the internal rudder frame that failed on one, and bent on the other?

Doane on http://www.wavetrain.net/ BTW, this is where he is answering a few questions in the comments.

"In retrospect, it is hard to imagine how all this might have happened. I think it is likely that most cats would have suffered some sort of steering or rudder damage from the hit we took, but our damage seemed bizarre. Securing the tiller arms to the rudder stocks with small set screws may not be a good practice, but in this case those screws should have acted as sacrificial fuses. Confronted with the huge force of the wave stopping the boat and thrusting it backwards, you'd think the screws would break off, leaving the stocks to rotate freely so the rudder blades would be saved. Instead the starboard set screw held and the welds securing the frame armature inside the rudder to the stock had apparently failed. Meanwhile, the port set screw had failed, yet the frame somehow bent anyway."