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44 Insight | UUVs that from towfish-like cameras attached to some sharks – will produce new insights into their social interactions, group behaviour and courtship. The study took place in the Inner Hebrides, off Scotland’s west coast, with the 2.03 m-long AUV acoustically tracking basking sharks that had been tagged with USBL beacons. It has been programmed to follow behind them autonomously, using the SharkCam to capture their movements. As it does so, the Remus 100 uses its other sensors to gather data such as water temperature, salinity and biological diversity as well as bathymetry, to determine where the sharks tend to travel relative to the seafloor. Initial footage from the video appeared to show the sharks moving up through the water column, searching for food, feeding close to the surface and swimming back down near the seafloor. The Remus used by the WHOI weighs 45 kg in air, has a top speed of 5 knots, a depth rating of 100 m and an endurance of up to 9 hours, with an operating range of 36 nautical miles (66.67 km) at 4.5 knots. Defence General Dynamics has updated its Bluefin-9 and Bluefin-12 UUVs, which are being delivered to Thales in support of the Royal Australian Navy’s SEA 1778 procurement programme. “After acquiring Bluefin Robotics in 2016, we wanted to take a clean- sheet look at the two systems, as we felt it was the right time to incorporate a full sweep of new electronics and other subsystems,” says Andy Rogers, vice-president of undersea systems at General Dynamics Mission Systems. “For example, we wanted to offer a high- end multi-beam sidescan sonar [SSS] to our customers, so both UUVs now have Sonardyne Solstice 3000 sonars as part of their survey mission package.” Another major objective of the upgrades was to reduce UUV downtime by making maintenance turnarounds easier and accessing the sonar data quicker. That was accomplished in a number of ways, such as incorporating real-time data processing into both UUVs and including a removable data storage module to cut the time to download data from hours to minutes. Another approach was to switch to an easily removable battery pack, to allow quicker swapping-in of a fully charged pack between dives rather than having to recharge on the deck of the support vessel. “All our Bluefin Robotics UUVs have fully flooded architectures, which means the UUV hulls aren’t pressurised. That makes them much easier to open up than a sealed and pressurised UUV if you want to remove a component such as a battery pack or data storage module and replace it with a fresh one,” Rogers notes. “Overall then, from the time you recover either UUV from the sea and perform standard hardware and software maintenance, they can be relaunched for the next round of a survey in less than 30 minutes.” The Bluefin-9 is a two-man portable craft, 23.8 cm in diameter and 2.42 m long, which can be launched from a rigid inflatable boat. It carries a 1.9 kWh battery for 8 hours’ endurance at 3 knots, and a 1 Tbyte removable data storage module. The Bluefin-12 is larger, at 12 in (32 cm) in diameter and 4.83 m long, and is designed to make it easy to swap and reconfigure different survey payloads across its modular sections for a range of missions. Four 1.9 kWh batteries provide it and its 4150 cm 3 payload capacity, with 24 hours of operating time at a speed of 3 knots. “We’ve also redesigned the thrusters on each UUV,” Rogers adds. “They use a vectored thrust design that steers the vehicle without the need for protruding fins, which reduces the number of points of failure on the vehicle; improved thrust now provides a top speed in excess of 6 knots. “This additional thrust provides a fast transit speed for reaching survey areas in applications such as mine countermeasures or oceanography.” In another naval development, Klein Marine Systems has received a contract from an AUV manufacturer to install its MA-X SSS technology on one of its next-generation systems, which is to be evaluated by the US Navy. Although most conventional SSSs generate what is called a nadir gap along the centre of the image, the MA-X is designed to remove that, removing the need to carry out overlapping survey lines for full area coverage, saving time and battery energy for UUVs fitted with it. In addition to shorter survey times to cover a given area, or being February/March 2020 | Unmanned Systems Technology The AUMD from C-Job Naval Architects would save considerable power and labour costs compared with the conventional approach to port dredging operations (Courtesy of C-Job Naval Architects)