Over the years, Practical Sailor has tracked the evolution in marine antifouling paints. Shaped by government regulations, environmental concerns, and industry innovations, the shift started with tin-based paints in the 1980s. After tin-based paints came under fire for the harm they cause marine life, copper-based paints grew in popularity. Now, concerns about the impact of copper on the environment have led to the development of copper-alternative paints, such as zinc-biocide and water-based antifoulings. We continue to sort through the data to help you find the best bottom paint for your boat. This report offers an update to our panel tests after six months and 18 months in the water as…