Ship noise affects the underwater environment, requiring acoustic assessment. Since Japan has no large-scale underwater ranging capability, JRC Tokki invested in a portable sound-intensity system from Brüel & Kjær. This static ranging system uses hydrophones mounted on a floating raft to make underwater Noise Source Identification (NSI) measurements on large vessels.
In order to get a complete characterization for the whole of the underwater structure of a ship, a portable system was needed that would enable field measurements. As the curvature of a ship’s stern and bow often varies, JRC Tokki needed a solution that could account for this by following the hull closely, at a uniform distance.