I am removing all of the bottom paint from the rudder area while the rudder is out to get a good assessment. I was looking closely at the bottom of the rudder tube and noticed what appeared to be unsaturated cloth. My plan is to grind the dry cloth out with a dremel and flapwheel which has worked very well for hard to reach areas in other projects and then fill the gap between the glass rudder tube and the opening just below it with thickened epoxy. I'm not sure if water could get in from there, but the fact that cloth seems unsaturated there and that it is below the waterline this is a good preventative repair.