I had set the centreboard to one side while I painted the hull and when I returned to it to finish it off I immediately realised that compared to the hull it was of quite a poor standard.
Clearly my painting skills had improved a lot since my first attempts on the centreboard!
No problem. I sanded the board back to a P220 finish, like this.
Three coats of primer followed, as here.
I was able to paint both sides at the same time by using these Paint Points to support the board.
The primer was sanded again to a P220 finish.
I applied four coats of gloss with a good brush rather than waste a roller, and when hard I wet sanded the board with P800 through to P2500 grits. Like this.
Lastly I used Festool polishing compounds to polish from a P5000 to a P11000 finish. The board was now perfectly flat, and smooth as glass! Like this.
That will slip through the water very nicely.