Experience with the use of a rigidly-mounted side-scan sonar in a harbour basin bottom investigation

Abstract

The issue of investigating seabed clearance is particularly important in harbour areas where depths are often only slightly greater than ship drafts. Additionally, the threat of usage of mine-like objects (MLOs) in harbour areas should also be considered because of the increasing number of terrorist attacks. This kind of threat also requires frequent sonar surveys in such areas. These survey operations need specific procedures and special equipment to ensure survey correctness. However, a given port׳s infrastructure, small depths and vessel traffic affect the survey process in a specific manner. A typical towed side-scan sonar (SSS) is difficult to use because of restrictions in the vessels׳ manoeuvring.In this paper the option of attaching a towfish to the hull of a survey vessel was examined . The results obtained during a real survey in Gdynia harbour along with the choice of survey vessel, way of fixing the transducer to the hull and the selection of appropriate sonar operational parameters are presented.