In a never ending battle to keep my tabs clean. I painted this year with 3 coats of Primacon and then a copper free anti-foul piant, we'll see how it works. I Kept the old zincs on the tabs to block the paint, worked great.
I feel your pain, I just sanded a thick layer of barnacles off mine and applied 3 coats of West System barrier coat.
Now 1 more coat of West System barrier coat and then the Petit Horizons. No fun with the boat on a trailer!