I have a heavy duty emergency rudder for a 40' boat that mounts into a cassette (the only way you can deploy a rudder at sea). It's not beautiful, but can be adapted to fit any boat between approx. 35-45'.
Text me at 707-721-2745 if interested.
P.S. I previously lost a rudder coming back from Pac Cup in 2002, and that experience informed the design of the one I am now selling.