A multi-aspect study of commercial coatings under the effect of surface roughness and fouling

Journal article, 2019

The paper presents an experimental study of surface and hydrodynamic characteristics for biocidal, non-biocidal antifouling coatings and hard coatings. In the study both smooth panels (Rt(50)≈40-90 μm) and panels with roughness commonly found on ship hulls (Rt(50)≈110-125 μm) were used. Measurements of drag were obtained from torque measurements in a rotating disk rig and the biocide content (Cu) of the coatings was measured using X-Ray Fluorescence instrument. The results show that Cu concentrations in coatings were sufficient to deter hard fouling such as by barnacles. The results from the drag measurements show that over the range of investigated test velocities, poorly applied antifouling biocidal coating with an induced roughness (Rt(50) = 116 μm) caused on average 13% higher moment coefficient () when compared to the same type of biocidal coating but with a smooth finish (Rt(50) = 43 μm). This paper demonstrates primarily how field-grown fouling affects the antifouling efficacy and drag performances of both biocidal and non-biocidal coatings. In addition, the paper also presents a correlation of drag and surface characteristics using a new scaling based on fouling pattern, fouling % cover and surface free energy.