ACOUSTIC DETECTION OF SMALL- AND MID-SIZED SURFACE VESSELS IN VERY SHALLOW WATERS Alessandra Tesei, Stefano Fioravanti, Vittorio Grandi, Piero Guerrini, Alain Maguer NURC, NATO Undersea Research Centre, V.le S. Bartolomeo 400, 19126 La Spezia, Italy Alessandra Tesei, NURC, V.le S. Bartolomeo 400, 19126 La Spezia, Italy, tel. +390187527242, fax. +390187527331, email: tesei@nurc.nato.int Abstract: The detection, localization and tracking of surface vessels for monitoring purposes is of great interest in areas such as marine natural parks, where navigation is limited and should be controlled. Nowadays the presence of big-sized ships in an area of interest can be easily detected and accurately monitored either by radar or via AIS system. However, small vessels do not adopt the AIS system and some of them, in particular rubber boats, have very weak radar signature, hence may be missed by usual monitoring systems. In these cases an alternative useful surveillance method can be based on the detection of underwater acoustic noise radiated by vessels. The acoustic signatures of small- to mid-sized surface vessels (ranging from rubber boats to fishing boat and tugs) are much less investigated in literature than those of slow, big ships, and can be extremely diverse. This work describes a bench of detection methods optimized for small- and mid- sized boats, and compares the preliminary results achieved by their application to a preliminary set of at-sea data. Acoustic noise was recorded in September 2010 by a single hydrophone located close to the seabed in very shallow waters in the coastal area of the Isle of Pianosa, in the National Park of Arcipelago Toscano, Italy. This work is partially funded by EU within the context of the ARGOMARINE Research Project. Keywords: Surface Vessel Detection, Small Vessel Characterization, Non Gaussian Noise