Thanks for the info Gorchew. I wish I would have seen these about 6 weeks ago, at that price I could have used them and built to them. For now I'm beyond that point and would have to backtrack a fair amount to utilize them.
I will wind up with much the same set-up - composite core, reinforced with aluminum, wrapped in fiberglass.
My lower blade is 36" long, 12" at the widest at the top, tapers to 8". This is a little wider than my OEM rudder, but not being a nautical engineer I decided to build oversize and cut it down later if needed. I tried to cut up a different project, that didn't work so well (that was a joke, cut down, cut up...never mind
Nice to hear another V 21 is under restoration. Mine too was basically free, now she's gorgeous and near new. Last year we had her on the water several times and were not disappointed at all. I've gone bow to stern, she's all new paint, seals, hardware, sails, interior, and rigging. I built a new trailer with all sorts of custom gadgets.
Good luck on yours.