56 Digest | SeaTrac SP-48 USV On top of the LOS RF connection, the USV integrates two cellular connections – a primary and a backup – as well as an Iridium SBD (short-burst data) system; the latter functioning as a backup (albeit a slow, high-cost one) for emergencies, particularly when cellular links go down, delivering small, periodic updates on where the boat is and if it still functions. “When you get out of cell range, primary satellite communications is handled by an Iridium Certus 100, which provides a good BVLOS connection to the SP-48, with high enough data rates to maintain a good position lock and to send commands much faster than SBD, as well as receiving some low-definition pictures from the cameras every five to 10 pictures,” Boeschenstein adds. “Hence, the Certus becomes our primary data link for most offshore missions, as cell networks don’t work far into the ocean, except maybe in a few networked parts of the Gulf of Mexico. We also have a battery operated tracking solution on the USV, so if it stops and all comms links drop for some reason, that gives a GPS ping for us to understand, without fail, where the boat is.” For passing vast amounts of data quickly, Starlink High Performance Dishes have been installed on a few customers’ boats, although, at 100 W, this system draws significant power (particularly compared with the Certus’ 8-10 W), so it is used sparingly when integrated. As of writing, SeaTrac is about to integrate a Starlink Mini for the first time. Though a lower-bandwidth system, its SWaP stands to make it a more sustainable fit to the SP-48’s power budget. SeaTrac has also integrated and successfully operated a Silvus highbroadband radio for Task Force 59, to function as part of its mesh radio network. Future Having sold many units, SeaTrac is determined to move on from building and operating single SP-48s to operating them as fleets or swarms, given their low cost and easily manufacturable nature. “You can survey huge areas at scale by having several of these USVs working together, to get a real, big picture of the environmental state of the oceans instead of looking through a straw at our planet’s giant, systemic problem areas,” Boeschenstein says. “To me, that’s a really exciting prospect: gaining so much operational efficiency. Having one operator watch one boat 24/7 is easy, but most of the time nothing is happening. There is minimal incremental cost for deploying one, two, three or more of these. “We’re not burning any fuel, and personnel are more than capable of monitoring larger fleets of USVs, especially if they’re intelligently working together to create a grand view of what is happening in the ocean.” December/January 2025 | Uncrewed Systems Technology SeaTrac SP-48 USV Monohull Solar-electric Length: 4.8 m (15.9 ft) Width: 1.4 m (4.6 ft) Draft: 42 cm (1.4 ft) Empty weight: 275 kg (606 lb) Payload capacity: 70 kg (154 lb) Maximum speed: 5 knots Nominal endurance: six to nine months Some key suppliers INS: Applanix Multibeam echosounder: Norbit Sonar: R2Sonic ADCP: Teledyne ADCP: Nortek Wave height sensor: Seaview Systems Additional sensors: Airmar Water data sensors: AML Oceanographic HD cameras: Axis Thermal cameras: Teledyne FLIR Satcom: Iridium Satcom: Starlink Winch/profiling system: SeaTrac winch with AML-3 or AML-6 instruments Key specifications While operating autonomously, the USV integrates a 916 MHz data link as its LOS data link, two cellular connections, an Iridium SBD system and an Iridium Certus 100 for satcom
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