Rudder head corrosion
The rudder head on my Helms 24 which is presumably aluminum alloy exhibits pitting corrosion at its lower edges, presumably below the water line. I recall reading that aluminum doesn''t do well submerged because it cannot form a protective oxide coating like exposed aluminum. I guess this is why the bottom part is corroded (and underneath the stainless steel straps of the pintle bolted to the sides of the rudder head, there is also a whitish powdery crud).
I am wondering if a zinc chromate primer would be a good barrier coating to prevent any further corrosion on the rudder head. I have disassembled it and wire brushed down to bare metal as well as I could. Any thoughts?