David, I had to google vacuum impregnate but now I understand the process. Sounds like a good solution if you were set up for it.
Mechsmith - I'd be interested in your suggestion of a friction clutch. Could you take a picture?
What I have so far is the upper portion that ties to the transom is all aluminum, built from 1/4 in plate. The lower rudder is a laminate with a polyethelene core and aluminum shell. Its pretty high tech if I do say so myself.
The plan was to use a spring system to hold the rudder down and up. The only danger is that when the rudder is pulled up, I don't want it to come up so fast that it hits the helmsman in the nose.
I'll take a couple of pictures tonight and put them up.