M_Boats: Bottom paint

My boat was kept for two years in salt water by the original owner, who painted the bottom with a copper-colored ablative bottom paint. I have trailer-sailed the boat for almost four years in fresh water, and the paint is now showing its age, besides making a big mess when washed with On and Off. Does anyone have any advice about how to remove the old ablative paint and what it should be replaced with? I was thinking of sanding, but the recent posts on gelcoat damage from sanding are making me rethink that and ask for help. Thanks, Rick M17 #633 Lynne L