UNDERWATER RADIATED NOISE FROM A LARGE PLEASURE CRAFT

The impact of underwater radiated noise (URN) by ship traffic has gained an increasing interest among scientists, ship designers and builders. It is now recognized that the underwater noise generated by human activities and in particular shipping noise can be harmful for the marine fauna and therefore urgent actions must be taken to tackle the problem. To this aim a virtuous example is represented by the Port Authority of Vancouver (CA) that, since 2017, has introduced important incentives and tax relief for those ships that prove to be particularly virtuous in terms of noise emissions radiated into the water. Up to now, most of the attention has been paid to study and characterize the noise emissions of large commercial ships due their worldwide diffusion. To this aim several measurements protocols have been issued both by international bodies (ISO, ANSI/ASA) both by the main classification societies. A lack of data is on the contrary present regarding pleasure crafts both as regards small boast and large yachts. In the present paper data coming from an experimental campaign for the measurement of the underwater radiated noise of one large yacht built by the SanLorenzo shipyards is presented. Noise has been measured for several operative conditions and speeds ranging from zero to maximum speed.