To save time in the spring, when you haul out in the fall, paint your boat with a copolymer ablative bottom paint such as Interlux Pacifica Plus, Pettit Ultima ECO, Interlux Micron CF, or TotalBoat Krypton. These paints have a fairly high copper content, a slime-fighting additive, and work well in high fouling areas, releasing biocide at a controlled rate throughout the season. While the percentage of copper is important, what also contributes to the effectiveness of these paints is the controlled polishing copolymer technology, which determines how fast the paint wears away.
In the spring, simply do a light scuff sand with an abrasive pad to activate the antifouling properties before launching the boat.