CRITICAL EXAMINATION OF A MULTIBEAM ECHOSOUNDER FOR THE FULL BATHYMETRIC AND GEOPHYSICAL SURVEY OF THE SS PERSIER WRECK IN BIGBURY BAY, PLYMOUTH, UK

Over the past decade or so multibeam echosounders have become the staple of bathymetric surveys in the field of hydrography. This however is only one of the functions of the multibeam system. Another aspect of the system is its ability to do a geophysical textural analysis of the seabed similar to a side scan sonar system. In this dissertation this ability was explored and compared to a side scan system and the objective that was explored was to prove whether it was possible to do a proper bathymetric and geophysical analysis of the shipwreck of the SS Persier as well as the surrounding seabed located at Bigbury Bay off Plymouth. Other aspects that were explored included the differences in resolution between the two different frequencies available in the R2Sonic multibeam system i.e. the 400 kHz and 700 kHz systems. To do the a proper evaluation of the system in its performance in backscatter textural analysis a full comparison was done with a similar survey done using a multibeam system and a side scan sonar over the SS Rosehill located at Whitsands Bay in Plymouth. The textural qualities of the mosaics presented by the two different systems were put to test and the breakdowns of their differences were explored. What was found was that while the multibeam system was able to get a better textural analysis, the side scan presented better photographic imagery of the features on the seabed