Systematic investigation of coating application methods and soft paint types to detect cavitation erosion on marine propellers

Cavitation erosion is perhaps the most detrimental result of the cavitation on propellers, which results in an increase in noise and vibration characteristics, loss of propeller performance as well as high maintenance costs. In this paper, some types of coatings and application techniques used in marine propellers have been tested by conducting series of cavitation erosion tests in the Emerson Cavitation Tunnel of Newcastle University. Therefore, this paper investigates the cavitation erosion phenomenon by conducting a systematic investigation of different paint-like coatings that were applied in different procedures on propeller blades. The blades were exposed to cavitation in a cavitation tunnel and erosion patterns were macroscopically analysed. The propeller blades were coated with off-the shelf commercial stencil inks, as well as S1 (a soft coating) which was largely preferred by major testing facilities but has recently been stopped to be produced. Within this framework, this paper aims to evaluate and establish a soft paint application method for cavitation erosion prediction by carrying out an extensive experimental test process. To achieve this aim, a series of propeller cavitation tests were performed in search of a promising detailed guidance for coating application for the erosion detection. In conclusion, promising coating application and improving preparation methods are outlined. Resulting pitting formations are correlated with the observed cavitation patterns and types. Amongst the tested alternatives of the coating application methods to apply soft paints, dipping appeared to be the most promising technique providing a uniform soft surface over the blades.