Boundary layer and roughness characteristics of hull coatings

This study presents an experimental investigation conducted at the Emerson Cavitation Tunnel (ECT) of Newcastle University to investigate the boundary layer and surface roughness characteristics of three commercially available hull coatings: a tin-free SPC, a new generation Foul Release coating and a novel nanostructured coating. In addition, two coatings that have been artificially roughened by mixing in sand grit during application were included in the study. These coating were roughened in order to mimic either hull surfaces that have been a while in service or poor quality coating applications. In order to examine the boundary layer characteristics of the coatings, a large flat plane model with interchangeable test sections was used. A two-dimensional DANTEC Laser Doppler Velocimetry (LDV) system was used to collect the boundary layer data of each coating. The measurements provided critical parameters including local skin friction coefficients and roughness functions. The surface roughness of the tested coatings was analysed using both a non-contact laser profilometer and a stylus instrument. The tests and subsequent analysis allows to compare the hydrodynamic performance of these antifoulings. The measured boundary layer data were analysed by using different analysis methods to predict and compare the skin friction characteristics of these coatings.This study presents an experimental investigation conducted at the Emerson Cavitation Tunnel (ECT) of Newcastle University to investigate the boundary layer and surface roughness characteristics of three commercially available hull coatings: a tin-free SPC, a new generation Foul Release coating and a novel nanostructured coating. In addition, two coatings that have been artificially roughened by mixing in sand grit during application were included in the study. These coating were roughened in order to mimic either hull surfaces that have been a while in service or poor quality coating applications. In order to examine the boundary layer characteristics of the coatings, a large flat plane model with interchangeable test sections was used. A two-dimensional DANTEC Laser Doppler Velocimetry (LDV) system was used to collect the boundary layer data of each coating. The measurements provided critical parameters including local skin friction coefficients and roughness functions. The surface roughness of the tested coatings was analysed using both a non-contact laser profilometer and a stylus instrument. The tests and subsequent analysis allows to compare the hydrodynamic performance of these antifoulings. The measured boundary layer data were analysed by using different analysis methods to predict and compare the skin friction characteristics of these coatings.C