Good to know.  I'd rather do a quick mid-season scrub when the boat is in the water than deal with antifouling paint each year.  Part of that is the expense and hassle, and part is because I like to launch in the spring before it's warm enough to paint.

  Thanks for the tip on CopperShield. 

        - Mike
 
Quick mid season scrub may be a bit ambitious.  In a marina in Fremantle (warmish water, lots of growth), I was scraping off weed and barnacles if I left it for a month and scrubbing it each week.  On XL2 (39' race cat in Brisbane) we set sanded it each weekend to remove the slime before a race.  Used sponges with carborundum on them.  As time passed, the bottom got smoother and we ended up using 400 grit.