rudder for Catalina 22

Apr 20, 2014
4
Catalina 22 Theewaterskloof Dam
Hi Guys
I have had my Cataline 22 since 1992 - sailing on an inland lake in the Cape of Storms (Western Cape Province) of South Africa.
The original rudder lasted 10 years before it broke.
I had a copy built which lasted 5 years before it broke (just at the end of the sleeve/housing)
We then attempted to build a new one, copying the design of the old one.
Material used 12mm marine ply, coated with layers of fibreglass and epoxy coating.
Well, it lasted 1 month before it broke again.
It also developed a tremendous vibration at sailing speeds between 6-10 knots of wind.
Any advice before we make the same mistake again?
Does anybody of the design specs for a really sturdy rudder?
Why the vibration???
Cheers and thanks
Wolf -the Explorer.
 
Apr 20, 2014
4
Catalina 22 Theewaterskloof Dam
Rudder design for Catalina 22

Thanks for the advice. It showed that we approached the making of it with absolute ignorance of stresses and strains.
Well, so much for doing it myself. I will have to get my clever sailing buddies to assist.
Thanks again