I had to paint my hull also due to my boat sitting in the marina. I got a gallon of 'new' type anti fouling paint from west marine. It's not the epoxies type. This stuff starts to break down and fall off but takes about two years. The advantages of this is that you wont have to scrape your hull when it's time to repaint again. It's great!! I painted about two months ago and have absolutely nothing growing below the waterline. One gallon was enough for my 21'er. I also had enough to put an extra coat around the waterline.

The older guy at west marine in Everett can explain in detail EVERYTHING you want to know about anti-fouling paint. I think I paid around $140 for a gallon??

Hope this helps...