High-Build Vinyl Coatings for Use on the Cathodically Protected Bottoms of Ships.

A number of high-build vinyl anti-fouling shipbottom coatings, formulated both for airless hot spray and conventional spray application, have been evaluated in the laboratory and on service vessels. The main objective of the investigation was to find an underwater coating system with equivalent performance to the Maritime Forces specified vinyl system, but one requiring fewer coats of paint and therefore lower labor costs and a shorter application time. In this evaluation, the formulations for hot spray and airless hot-spray application proved better than those formulated for high-build application with conventional spray equipment. A four-coat system consisting of one coat of vinyl wash primer applied by conventional spray, followed by a high-build aluminum-vinyl primer, an intermediate high-build vinyl-aluminum anti-corrosive coat, and a coat of 1-GP-123 vinyl cuprous oxide anti-fouling, all applied by hot spray, achieved the required ten mil minimum total thickness and, on the basis of the laboratory and ship trial performance, can be considered for general use. Author