Rudder is stainless steel frame welded on a stainless post, then filled in with fiberglass... your water intrusion probably comes from either the entry point of the rudder post at the top of the rudder, or from the top of the tube in the cockpit under the emergency steering plate. These rudder posts were filled with open cell foam allowing water a one way in and no way out unless you turn the thing upside down. I wouldnt be concerned. Mine has water too and its solid as a rock. But If you ARE really concerned, break/ grind it apart and rebuild from the frame up... lots of work= piece of mind. Otherwise put it in a huge contractor bag with a dehumidifier. Works great.
Then seal up the post entry into the glass with marine sealant, and you're done.
