Chuck:Getting bottom paint off depends a lot on what type of paint is on the boat now and how firmly it is adhered. Modified epoxy, for example, is VERY hard to get off. Soft sloughing and ablative paints come off relatively "easy." Most marinas rent out heavy duty sanders that are environmentally safe. Rent one if you don't have a heavy duty sander yourself. Start by using a scrapper to get any loose paint off. Often, with as many coats as you have on your boat, you'll be able to chip off big patches of paint right down to the gel coat. After that, get on your respirator, goggles, and Tivek suit, put some 40 grit sanding disks on the sander, and hit start. If you have never done this before, be careful not to cut into the gel coat once the paint comes off. This is a dirty job, but with luck you can do it in an afternoon on a 22 ft boat.