Submerged surfaces exposed to marine biofouling – Experimental investigation of cleaning parameters effectiveness

Physical cleaning, an important factor in maintaining ships' hulls free from biofouling, can help to prolong the lifetime of fouling-control coating systems. This study investigated how mechanical cleaning parameters (cleaning force, duration and frequency) affected antifouling coatings' performance including fouling resistance property and cleaning efficiency using a specially designed manual cleaning system. Meanwhile, coating surface conditions, including visual appearance condition, roughness, contact angle were evaluated in detail. Biocide release rates of copper-based soluble antifouling paint (Cu-AF) under different cleaning conditions were also assessed by Scanning Electron Microscopy - Energy Dispersive X-ray (SEM-EDX) analysis. Results from the field testing in Danish sea area showed that cleaning frequency affected more than cleaning force and duration on antifouling coating performance. Algae glue attachment increased the difficulty in the cleaning of non-coated acrylic surface (A-BS) and fluorine-based copper free insoluble antifouling paint (F-AF). For Cu-AF coated panels, no significant mechanical damages were observed after cleaning. For F-AF, scratches formed on the coating surface after cleaning were more related to cleaning force and cleaning frequency. The biocide release rates of Cu-AF under various cleaning condition were between 15.7 and 24.6 μg Cu cm⁻² day⁻¹. Gentle cleaning of Cu-AF with proper frequency has little influence on the copper release rate. This study provides guidance on cleaning strategies for antifouling coatings.