Swath mapping in shallow water is a challenging prospect, and generally involves a dual head multibeam echosounder (MBES) system if bathymetry is required whilst retaining survey efficiency. In 2014 Acoustic Imaging purchased a dual head R2Sonic 2020 system to address these sorts of surveys as this represented (in our opinion) the best solution at the time and we had the budget to afford a MBES system. However, we were also aware other solutions existed including interferometric (or phase differencing) systems.
Technology has advanced with phase differencing systems over the past 3 years and a system we’ve been monitoring is the Edgetech 6205 Multiphase Echosounder (MPES). Through discussions with Edgetech over the past 6 months we felt an Australian demonstration of the system was warranted and so we organised a vessel (courtesy of the Department of Transport, WA), supporting equipment (in particular a POS MV position and orientation system), and personnel to show the system to interested clients. On January 18th, 2017 thirty clients from 12 different companies were rotated through an on-water demo across six 1-hour time slots to show system capabilities.
Evan Martzial, the on-site Edgetech representative and Bathymetric Product Line Sales Engineer, provided in-depth discussions of the advantages offered by the 6205 MPES system. These include wide swath coverage (demonstration data acquired at a swath width of 8x water depth), “clean” real-time bathymetry through optimised filters, dual frequency sidescan sonar backscatter data co-registered with bathymetry, flexibility over system components (swapping of transducers to support different frequency operation), and ease of installation. The system also allows entry into the swath mapping market at a lower price point than most multibeam echo sounder systems.
On the day preceding the on-water demonstration, a number of areas were surveyed to illustrate system capabilities. These included a breakwater survey, a survey beneath a pair of bridges where satellite blockages were prevalent, a survey in a region of the Swan River where the dual head 2020 system was tested, and a single swath where maximum width of bathymetric coverage was assessed. Two of the sample data sets along with supporting data are provided in the link below.
Please note that the 6205 system was not tuned for optimal hydrographic performance for either of the sites; our focus was on capturing representative data in a very finite period. If you are interested in assessing whether the system can meet particular IHO data quality specifications, other data sets can be made available.
Some of the results achieved from the demonstration data are shown in the accompanying images. As a general statement, system performance was very good and data processing / cleaning was relatively straightforward. No nadir gap nor nadir artefact are apparent in the data, and adjacent lines match up well both horizontally and vertically. The sidescan sonar backscatter data when draped on the bathymetry highlights small features and provides an essential cross-reference to ensure that seabed features are not missed. Further analysis of the data is underway, and future demos are being scheduled for the east coast of Australia.
For lease/purchase options or consulting services related to the Edgetech 6205 MPES system, contact firstname.lastname@example.org.