Mark,
I was just looking at the images of your 18. Nice.
I put white Interlux Performance VC 2 part on my 23, which is not anti-fouling.
We just put Dolphinite's new clear anti-fouling on my brother's 23 unpainted bottom. It sprayed on easily and was barely visable. We'll see how it works out. They also make a white.
Dolphinite