Just a thought ! Instead of painting, roll on a coat of Epoxy mixed with graphite, up to the 3-4" waterline.
Lightly sand and put it through the paces !
The Epoxy shouldn't cost much more than varnish, but may add some speed ! I've always felt that the graphite helped, but I can't verify it !
Now would be a good time to find out, beings you have some veteran racers to test it !
You could maybe sharpen the bow stem at the same time .
Again ! Thoughts going through this Old Guy's head !
Jim