Accurate predictions for noise levels of cavitating propellers now possible


As underwater radiated noise levels in the oceans increases, MARIN


has investigated just how much cavitating propellers are to blame. Frans Hendrik Lafeber, Johan Bosschers & Yvonne Koldenhof, f.lafeber@marin.nl


Figure 1: Cavitation pattern on the propeller of the research catamaran T


raditionally, underwater radiated noise is mainly of interest for naval vessels and fishery research ships.


Nowadays, however, there is a growing concern that marine life is affected by the rise in background noise levels in the oceans. Marine mammals and fish use sound to communicate and to sense their environment and this requires low background noise levels. The rise in noise levels is being caused by an increase in shipping, among other factors. Therefore, the EU has included underwater radiated noise emanating from shipping in the methodological standards for a healthy marine environment.


There is, however, a lack of knowledge about the actual noise levels produced by (merchant) ships, although it is known that one of the dominant noise sources is the cavitating propeller. The EU FP7 Suppression Of underwater Noise Induced by Cavitation (SONIC) project aimed to assess and mitigate the impact of shipping noise on the marine environment. MARIN, which was the coordi- nator of the project, focused on the further development and application of computational and experimental tools to predict propeller cavitation noise and on generating ship traffic


22 report


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