the loss of rudders on Hunters and Catalinas and the like seem a little too common. The armature they build these over seems not that durable. A new rudder (or a rebuilt one using the existing shells) wouldn't cost all that much compared to many other expenses of a cruise. And you would know what was in there. I hope this guy posts pictures of what he finds. Often there are just some plates welded to the rudder post, in the past these have even been mild steel rather than stainless, thinking was that it is sealed inside the rudder envelope. Not really a good way to build a rudder - the plate has very little torque resistance, and there is no hope of keeping the water out long term. Fiberglass over steel is a pretty difficult construction method to do right, I haven't seen a method that would inspire confidence.