Sea Technology

DEC 2018

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

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Page 21 of 52 December 2018 | ST 21 and whenever possible will likely be a key factor in successfully un- dertaking needed infrastructure up- grades. Selection Criteria Both military and commercial USV customers typically consid- er several criteria when choosing which technology to use. One is en- durance (underway time) and per- sistence (on-station time), as well as the need to launch and recover the unmanned asset. Since many in- frastructure survey projects involve launching and recovering the USV at some distance from the survey site, unmanned vessels with low en- durance and persistence can drive up costs to unacceptable levels. A second factor is range, closely related to endurance. Affecting the range is whether the USV must be controlled via line-of-sight links, or whether it can operate beyond line-of-sight using military or com- mercial satellite communications. Where survey work is involved, distance and obstacles often make commercial satellite communica- tions the preferred option. A third factor is scalability. While using a single model of an unmanned surface vehicle can al- low for a variety of functions, if a USV is part of a family of unmanned surface vehicles of the same basic construction and configuration, this greatly enhances the options for use. For bathymetric survey work, this might involve using a smaller USV to get into tight confines and a larger USV to deal with high-speed currents or other dam-created tur- bulence. A fourth factor is payload capac- ity. Extended payload capacity en- hances the utility of any USV. This includes not only how much weight the USV can accommodate to sup- port various sensors but how these sensors can be packaged on the un- manned surface vehicle to enable it to have the most operational flexi- bility. Also important is the ability to switch sensor packages in the mini- mum amount of time. A fifth factor is durability. The harsh maritime environment can damage, disable or even destroy small vessels like unmanned sur- face vehicles. If a specific USV de- sign is restricted to calm sea states, its operational value is greatly di- minished. This is one reason why those seeking to use USVs for bathy- metric surveys and other infrastruc- ture inspection efforts often turn to USVs that have been "wrung out" in military exercises, experiments and demonstrations. A sixth factor is speed, includ- ing: most economical cruise speed, burst speed and speeds in various sea states. In much the same way as high endurance, persistence and range, high speed can lower costs, especially in extensive survey work. As readers of Sea Technology know, the commercial uses of un- manned surface vehicles are grow- ing rapidly. This is due to the fact that these USVs are proving to be increasingly adept at doing "dull, dirty and dangerous" work in com- mercial applications as they do in the military missions that keep war- fighters out of harm's way. Look to these pages in the future for addi- tional applications of this technolo- gy. ST Captain George Gal- dorisi (U.S. Navy, retired) is a career naval aviator whose 30 years of active-du- ty service includes four command tours and five years as a carrier strike group chief of staff. He has a graduate degree in oceanography and has worked with unmanned systems throughout his Navy career. USA 1.508.291.0057 6205 S SWATH BATHYMETRY & SIDE SCAN SONAR • Co-Registered Dual Frequency Side Scan & Bathymetry • Unrivaled Swath Coverage in Shallow Water (When Compared to Other Single Head Systems) • IHO SP-44 Special Order Compliant • Universal MRU Mounting Plate • New Discover Software Traditional side scan showing motion artifacts in image Motion tolerant side scan image SHALLOW WATER WIDE SWATH BATHYMETRY WITH NEW MOTION TOLERANT SIDE SCAN "Using low-cost, off-the-shelf unmanned vehicles to replace human operators when inspecting infrastructure wherever and whenever possible will likely be a key factor in successfully undertaking needed infrastructure upgrades."

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