The ACORN Design and Decision Tool is now available for download and use. This application has been designed to provide developers of wave and tidal devices with information about surface degradation mechanisms that might be expected during service and which coatings might be useful in mitigating their effects. The application guides the user through a series of selection criteria based on the type of type of device being used and the sub-systems that could be affected during service, before providing recommendations for coatings that could be applied.