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.

Data from short-term biofouling assays are frequently used to evaluate the performance of antifouling (AF) coatings. There are a large number of factors, however, that may influence community development. One such factor is colour. The hypothesis was that differences in colour may impact the short-term development of a biofouling community and therefore bias the results. An experiment was designed to investigate the effect of black and white substrata on settlement of fouling organisms in the field. Both Ulva sp. and Spirorbis sp. had significantly higher settlement on black surfaces. This result emphasises the importance of considering colour and other factors when undertaking short-term testing of AF coatings.

Grooming may be defined as the frequent and gentle cleaning of a ship hull coating, when it is in port or idle, to prevent the establishment of fouling. This study assessed the effectiveness of grooming with a five-headed rotating brush system on epoxy, ablative copper and two silicone fouling release (FR) coatings. These coatings were placed under static immersion at Port Canaveral, FL on a weekly and biweekly frequency. The results showed that grooming reduced fouling on all surfaces and was able to prevent fouling on the ablative copper and FR coatings when performed weekly. It was concluded that the grooming tool used for these tests was sufficient to remove biofilm and most hard fouling. However, when fouling pressure increased or when grooming was performed less frequently, insufficient forces were imparted by the brush to remove all of the established hard fouling organisms.

More than 90% of US Navy Ships are coated with copper ablative paint. These ships may spend long periods of time pier-side, which makes them vulnerable to fouling. Hull grooming has been proposed as a means of maintaining the coatings in an operational condition. This study investigated the effect of grooming on a copper ablative coating exposed statically for six years. Grooming was performed weekly or monthly with controls left ungroomed. The fouling community was visually assessed, dry film thickness measurements were taken to monitor coating loss, and the copper leaching rates were measured. It was found that weekly and monthly groomed surfaces reduced fouling, and the ungroomed surfaces became fully fouled. Coating loss was similar for weekly, monthly and ungroomed surfaces. The results suggest that grooming is a viable method for maintaining copper ablative coatings in a fouling-free condition without adverse increases in the total copper output.

The application of a proactive grooming program to manage the fouling control coatings applied to ship hulls provides an opportunity to address the climate crisis, invasive species and the discharge of biocides into the marine environment. A large percentage of the total power required to propel a ship is to overcome the viscous drag created between the hull and the water. The powering penalty due to increases in coating roughness and the development of biofouling are well documented. In addition, poorly maintained fouling control coatings may lead to the transportation of invasive species. In-water hull cleaning is therefore an important part of ship operations; however, this is typically implemented as a reactive measure when fouling reaches a critical level and requires powerful machinery which damages the coatings, creates unwanted discharge and in many locations the discharge will require capture and disposal. Ship hull grooming is being developed as a proactive method to manage fouling control coatings that will ensure that they are maintained in a smooth and fouling free condition, there is no transport of invasive species or excessive discharge of material that occurs during cleaning. This manuscript will summarize the findings of many years of research and development.