Hi Rotto,
first of all well done on the replacement rudder, thats a great job!
my redwitch rudder has broke twice before and I have had my most recent made from the original fibreglass mould with a timber core.
I originally had an oregon rudder, but that broke at the lower rudder gudgeon after it developed a vertical split
The next rudder was fibreglass with no core and hollow at the water line, all it took was a bit of load from surfing and that went too (coming back from rotto...)
My new rudder was made by Brett Burvill at Windrush Yachts for $890, it's a pretty reasonable price, and takes the effort/stress out of making one yourself

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the finish was pretty good, but the moulds are very old, and have a few dings in them
I can hook you up with the moulds if you want just pm me, or email o_marshall@hotmail.com