Sea Technology

FEB 2014

The industry's recognized authority for design, engineering and application of equipment and services in the global ocean community

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20 st / February 2014 www.sea-technology.com for untethered deployments and long-term data collection in remote or deep-water environments. This submersible echosounder system is capable of collecting and recording split beam data over an extended period of time with no surface tether required. The University of Washington and the Northwest Na- tional Marine Renewable Energy Center (NNMREC) work- ing with BioSonics, successfully deployed a DT-X SUB echosounder in Admiralty Inlet, Puget Sound, for fve weeks beginning June 2011. The study location is a proposed Sno- homish Public Utility District tidal energy demonstration project site. Information gained is useful to project develop- ers in assessing the relative suitability of locations for long- term hydrokinetic facility deployments. Deployment Methods. The DT-X SUB was deployed as part of an array of battery-powered monitoring sensors af- fxed to a seafoor observatory platform. The system was autonomous and required no surface tether. Echosounder confguration and duty cycle were programmed at the sur- face. The echosounder operated at a 10 percent duty cycle, alternating between active pinging and sleep modes to max- imize temporal coverage and battery life. An integrated ori- entation sensor recorded the aiming angle of the transducer for accurate water column volume and fsh target angle cal- culations. The system was retrieved using acoustic releases, and the data fles were processed for fsh abundance, distri- bution and behavior information. The DT-X SUB system components were as follows: PRE- VCO (Fountain Hills, Arizona) A811SS TB pressure housing containing a DT-X split beam echosounder; a 200-kilohertz split beam transducer with internal orientation sensor; elec- tronics and specialized software for automated operations, data handling/storage, and shutdown/restart capabilities; four 80-ampere-hour, 24-volt, deep-cycle batteries, manu- factured by DeepSea Power & Light (San Diego, California); and an Oceanscience (Carlsbad, California) Sea Spider tri- pod mount. Results From DT-X SUB Deployment. Processed data verifed the expected density distributions across time and space. Overall, NNMREC concluded that it is possible to adapt existing acoustic instrumentation for autonomous de- ployments in high-fow environments. However, it was also noted that while data storage capacity is not an issue, lim- ited power availability restricts sampling density, therefore it is important to ensure that power supplies meet sample design requirements. Researchers also concluded that more A Teledyne Marine Systems Company www.webbresearch.com Six models to choose from and a catalog of options. Choice is good. APEX® Autonomous profling foats remain the most cost efective, yet advanced, profling foats available. From the APEX Argo foat, an industry standard, to our newest APEX Deep, Teledyne Webb Research ofers proven performance and the broadest range of confgurations and options in the industry. • Argo • BioGeoChem • Advanced Multi-Sensor • Electro-Magnetic • Deep • Engineering Special Choice. You asked and we delivered. See us at Oceanology International - D100 q Argo q Biogeochem (BGC) q Advanced Multi-Sensor q Mixing and Vorticity q Engineering Specials q APEX Deep Integrated split beam and imaging sonar display. Feb2014.indd 20 2/11/14 4:02 PM

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