Marine plywood comes in several grades, each suited for different applications based on the level of exposure to water and the desired aesthetic. The most commonly used grades include A-grade, B-grade, C-grade, and D-grade. A-grade marine plywood is the most premium, with a smooth surface and minimal defects, making it ideal for visible areas of boats and yachts. B-grade plywood is sl... http://mayoworld.com/suppliers/marine-plywood-grades