At Cherubini we found that most of our foam-cored C44 rudder blades have gone rotten with the years. One of my conclusions was that people keep removing the cute teak fiddle on the top and taking it home in the winters to revarnish it (it should be painted as part of the boot stripe); and, when it got reinstalled with less than 5200 and/or mishmash, it was working back and forth and water was getting in through the mounting holes. That rudder is very stoutly made, the rudder pipe is phenomenally strong, and we concluded the foam core serves no purpose whatsover, so it's been omitted completely from newer and repaired boats.