Silent towing carriage in the Depressurised Wave Basin


Supporting silent ships: measuring underwater radiated noise from cavitating ship propellers


Have you ever had problems talking to someone in a noisy environment such as a busy restaurant? The same happens to marine animals, which use sound to sense and interact with their environment: for communication, navigation, finding prey and even for self-defence. High ambient noise levels, which include a contribution from shipping, have an adverse impact on marine life.


Frans Hendrik Lafeber, Thomas Lloyd & Johan Bosschers f.lafeber@marin.nl


20 report


than doubled since the 1960s, anthropogenic noise in the oceans has actually increased eightfold. This shows that ships are not only more numerous but that individual vessels have also become more noisy due to increased size, speed and delivered power. This often leads to more cavitation, which is one of the main sources of underwater radiated noise (URN).


T


he world’s oceans are becoming increasingly noisy. While the size of the global commercial fleet more


Recently, shipping noise has received regulatory attention. Class rules include noise limits for fishery and seismic research vessels because self-noise can influence the opera- bility of such vessels. Nowadays, there are URN-related class notations for other ship types. These can be used to show that the URN of such a vessel has been controlled to reduce the impact on marine life. It is likely that in the near future local regulations concerning URN will come into force to protect marine life in specific sensitive areas.


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