Mike, for what it's worth, chord on my rudder was short, and the glass layup (after removing gel coat) did not wrap around the leading edge, so the solid core sheet (some kind of thermoset resin?) was exposed - I think a weakness in design/construction. I built up leading edge, brought radius to spec and reinforced front. Thickness is only a few mm high on each side, after fairing with epoxy (thinner than original gelcoat). I didn't think its worth planing down to balsa. Core inside gudgeon bolt holes was cracked. Bored-filled-re-drilled holes to eliminate leaking. Dried-out rudder lost 3-4 lbs. Now weighs about 77lb. w/hardware.
