The use of proactive in-water grooming to improve the performance of ship hull antifouling coatings

Abstract

The US Navy operates a large number of ships, however, unlike most commercial vessels they typically spend long periods of time in port where they may become fouled. This study investigated the feasibility of applying light cleaning (grooming) to maintain four surfaces free from fouling. The test surfaces were an ablative copper antifouling (AF) coating, a silicone fouling release (FR) coating, a two part marine epoxy, and a solid sheet of polytetrafluoroethylene plastic. The surfaces were exposed to static immersion in seawater on the East coast of Florida for 120 days and subjected to 3, 6, 12, and 24-day grooming intervals. Pre-groomed and post-groomed fouling conditions on each test surface were assessed and the maximum required lateral forces at each grooming event were measured. The results showed that grooming prevented or reduced the development of biofilm on the ablative copper coatings. The FR coatings that were groomed at the 3- and 6-day interval remained free from fouling until exposure to severe fouling pressure, which caused the 6-day interval to develop a small amount of fouling. Both the polytetrafluoroethylene and epoxy surfaces became fouled at all grooming frequencies, but fouling was reduced for the 3-day grooming frequency. The lateral forces required to groom the surfaces, with the exception of the FR coatings, increased with time. The results demonstrated that frequent grooming can have prolonged, positive effects on the AF performance of coatings.