Stainless steel can corrode, especially in crevices that trap salt water. The rust then weeps, leaving unsightly stains on your boat’s finish. To remove the stains, use a product such as FSR (fiberglass stain remover) from Davis ($10.99 per 16-ounce jar) or Star brite Rust Stain Remover ($11 per 22-ounce spray bottle).
Both products are safe to use as directed on gelcoat and painted marine surfaces. Apply FSR with a brush or towel, or just spray on the Star brite. Rinse thoroughly after it sits for a few minutes. Repeat on stubborn stains. To prevent stains from recurring, replace the offending piece of stainless-steel hardware and be sure to fully bed the new installation with a marine sealant, such as 3M 4200, to minimize crevices.