Kurt, that's interestin....
All that is really required at the bottom of a rudder shaft is a decent BEARING - and even that could be some spaceage material. Super acetal. And it could be designed to be easily replaceble.
Don't know if the obvious alternate materials, kevlar and carbonfiber plus a twopart plastic are the optimum underwater materials. Not yet, but something will come along.
Our shoe is a nice tidy little bronze burrito that disappears as an appendage. Its plastic/fiber replacement would be noticeable and might just as well be a bit larger and longer and bolt on directly to the bottom of the keel without being dapped in.. Have seen boats that instead of a shoe have a super gudgeon just up from the bottom for the rudder end. That moves the hinge up from the more vulnerable end of the keel position. And a design like that actually might work for the Ariel/Commanders.
Siliconbronze is an ideal material. Don't think that any epoxy composite can equal the stuff.
I agree with your rudder upgrade too. Occured to me once that the rudder doesn't care if it has a single or twopart bronze rod to swing on. Our rudder has a bearing at the very bottom of the shaft and at the top. (And perhaps at the intermediate strap gudgeon.)
The inbetween can be square sectioned, I-beamed, or any shape - OR doesn't even need to be there. That 1" bronze rod is,what, 20#? We only need it's roundness and toughness at the bottom and the top. It can conceivable be any other material inbetween. Or can just be whatever the blade material is.
A composite rudder that didn't depend on a huge 6 foot long, one inch diameter pin would be a great design challenge. As to the rudder having a hollow rod, I noticed in Alberg's original drawings in the Manual a 2" shaft - which ofcourse would be hollow.
Or if on the back end of a wooden boat would be two inches of white oak or teak. And the attachment method gudgeons and pintles. With the blade material inbetween!
Our original rudder and shoe are imco holdovers from pre-fiberglass history, from the wooden boat days.
The bronze shoe especially seems to belong on the end of a keelpost timber, not barely holding on to a plastic boat that really isn't capable, the way it was molded, to really hold the fitting. I mean the shoe is a wood boat fitting on a plastic keel.
I think a modern design upgrade of both is a great idea.
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