The invention relates to an antifouling paint having a binder comprising a rosin material and an auxiliary film-forming resin, the paint including an ingredient having marine biocide properties, wherein the binder comprises a blend of the rosin material and an auxiliary film-forming resin in ratio 20:80 to 95:5% by weight, the auxiliary film-forming resin comprising 20-100% by weight of an acid-functional film forming polymer (A) whose acid groups are blocked by groups capable of hydrolyzing, dissociating or exchanging with seawater species to leave a polymer soluble in seawater, the blocking groups being selected from quaternary ammonium groups which form a quaternary ammonium salt of the polymer and quaternary phosphonium groups which form a quaternary phosphonium salt of the polymer, and 80-20% of a non-hydrolyzing water-insoluble film-forming polymer (B).