Re: rudder failure?
Thank you and that is what I did. Tapped for soundness. All good and I set in furnace room for a month to dry out. Ground down lip/ridge around outside edge where two sides joined to create a flat surface, filled bolt holes with epoxy, ground down and fiberglassed around edge and over holes. Gel coated.
Worked very well. Sailed all last summer with no issues and rudder this year still looks good.
Tapping was definitely best method combined with thorough drying before reparations.