Underwater radiated noise from marine vessels: A review of noise reduction methods and technology

Marine anthropogenic noise has increased significantly over the past few decades, and a growing body of research is highlighting the negative impacts this is having on marine eco-systems. With increasing pressure to reduce the noise generated by commercial and other shipping, there is a need to develop new technologies and look at how existing technology can be applied to reducing vessel noise. In this review, the sources of underwater noise from marine vessels are outlined and a range of devices and technologies are assessed to see how they can be applied to reducing it. Covering cavitation, propeller and flow noise, and machinery noise, a wide range of technologies are reviewed with differing levels of maturity. It is found that there already exists a wide range of technologies that could be readily applied to many vessels, and there are others in earlier stages of development that could provide substantial benefits in the medium-term. However, there is still a lack of quantitative data on the effectiveness of many noise-reducing technologies, particularly at full-scale. This makes legislation more difficult to enact and, together with the lack of economic incentives, is limiting the adoption of such technology by the marine industry.