Removed the epoxy filler(?) and the white rubbery material covering the mid-rudder gudgeon. The gudgeon is a Schaefer part connected to the hull by two round head machine screws and nuts.

Sanding to "get the red out".
Sanded the starboard side waterline from midships aft and a bit as the bow. Sanded the hull from about the depthsounder aft.
Sanded the port side keel aft of the scupper to "get the blue out".

before today's sanding.
after today's sanding, after rinsing away the sanding dust.