Seasats Lightfish USV | In operation for a copper-coating treatment across much of the Lightfish to protect against buildups of algae and barnacles. A physicist at sea As Lightfish maintains its course to Hawaii (or Guam or Japan, depending on the time of reading) a prudent selection of navigation systems provides a first layer of aiding data that keeps it on track. Specifically, an IMU and GNSS receiver have been chosen off-the-shelf to maximise precision within the bounds of Seasats’ affordability philosophy. The second layer, however, is a software-derived aiding source that is unique to the company, which Rodriguez refers to as its onboard physics model, and he cites it as a key part of how Seasats provides GNSS-denied navigation to those various government organisations among its prospective customer base. Development of the model began alongside the design of the Lightfish’s first physical prototype, as part of the company’s internal simulations to inform CAD work ahead of real-world sailing tests. Access to that simulator is now given to each customer to simulate their missions using digital twins and observe how toggling power loads or other parameters may benefit mission runs. “The same physics model inside our simulator is also constantly running inside Lightfish, so, for instance, if its main computer knows it is applying half power to the motor, then it knows how fast it should be travelling through the water and the local weather. Similarly, it can track for steering impacts from the rudder and roll or heave through the IMU,” Rodriguez explains. “So, if it sees a significant divergence between where the GNSS claims its position to be and where it knows it should be, it can first alert the operator that there might be spoofing or jamming going on, who can then trigger the USV to use the physics model as the primary navigation data source. At that point it becomes 100% autonomous, as in not even using external aiding data for navigating anymore.” Knowing that persistent remote monitoring and tracking of autonomous assets remains a critical requirement for most users, the USV is equipped with a cellular modem for terrestrial BVLOS comms, Iridium Certus and Starlink radios for satellite-based data links, and an Iridium short-burst data (SBD) radio conventionally used for sending small packets of emergency telemetry or alerts. As well as the redundancy entailed by integrating four different data links, the cellular modem is keyed for two telecoms providers. Lightfish is also programmed with a system of failovers and prioritisations for its different comms technologies, intelligently sending varying sets of information over different radios as required. “Obviously, you can’t send nearly as much data over SBD as you can with Starlink, but all of that plus the backup tracker ensures you could have a power failure or the Iridium constellation could crash out of the sky, and end-users would still be able to see where the platform is and probably still be able to send it commands,” Rodriguez says. Tomorrow is tomorrow The exact landing point in Japan is undecided, although doing so can be decided ad hoc depending on weather conditions and discussions with local authorities and partners. Once the journey is complete, Seasats will recover the USV and analyse it as standard for any necessary maintenance or repairs, as well as evaluating for any performance gains that the boat could be updated for (although only minor changes, such as adjustments for added biofouling resistance, would be expected at this point). Afterwards, rather than undertake a new specific, non-customer journey, Seasats anticipates focusing on growing as a company, having raised a new round of funding in February. “We are going to be hiring new people and expanding our team, potentially to launch new, larger classes of USV, and to continue expanding our manufacturing, with big gains to be had in cost optimisation, consistency and quality control,” Kramers says. As Rodriguez continues: “Not every customer asks to have a USV delivered to them within two days, but there are those who want an international-sized survey done next month. That’s only going to be possible with boats on the shelf, and right now there’s four Lightfish on our shelf. “Even though production has a slight edge right now, we’re aiming higher. Once the Pacific crossing is complete, and we’ve shown what we can do, I’m really excited at the thought of being able to send our USVs all over the planet – to have Lightfish gathering data from the Arctic to the Indian Ocean, across the Pacific and the Atlantic, as both main and support survey vessels. “I don’t know what keeps Max and the others up at night, but that’s what does it for me.” 67 Uncrewed Systems Technology | April/May 2025 Weight: 132-192 kg Top speed: 4.5 kts Practical endurance: six months Theoretical endurance: Infinite Payload capacity: 27-50 kg Payload voltage: 5-28 V Payload peak power: 200 W Max range without solar: 575 nm (estimated; actual figure may be higher) Some key suppliers Motors: Torqeedo Satcom: Iridium Certus Satcom: Starlink Short burst comms: Iridium SBD Key specifications
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