km mrgnstrn's rudder method
Starting on pg11 of this thread, this method uses plywood to build the rudder.
It would be most useful for a rudder with an aperture, and relatively simple and elegant way for a single piece straight shaft
It uses the same 1" silicon bronze rod for the shaft and smaller available bronze rod drilled through - or tapped into the shaft could be done without welding.`
I believe the plywood could be sheathed or wrapped in glass or just sealed and epoxied if you want the traditional/restored look of plank married to the shaft.
Without thinking twice, I would use Hydrotek meranti plywood from a well established dealer. British Standard: BS 1088. No american plywood merits this high grade. It is perfect plywood if you are following mrgnstrn's method because it is clean, tight, voidless, modestly priced material for woodworking tools It would make a really fine plywood rudder imco.
This rudder when sealed well will probably take extended drying out periods if the boat is pulled for the winter or for traveling.
If put together with good epoxy it would last another 40 years. Damage would be fairly easy to repair - and if it had to be wrapped with fiberglass later to keep it going, that could be accomplished simply. BS-1088 meranti is engineered from red lauan. Imco it will do better than any other plywood underwater BUT edges must be totally sealed.
It will make the tapering and a thin trailing edge that much easier. I have bought meranti dead flat, every sheet of amerkin ply has a built-in curve. Flat material will be so much easier to taper with mrgnstrn's method. Might even factor in a modern foil shape by spreading microlight filler on the flats and shaping with a belt sander - adding a light fabric skin to protect the surface.