Unmanned Systems Technology 018 | CES show report | ASV Global C-Cat 3 USV | Test centres | UUVs insight | Limbach L 275 EF | Lidar systems | Heliceo DroneBox | Composites

28 that two people can break it down, carry it to the water’s edge, reassemble it in situ and push it into the water. The catamaran breaks down into two hulls, the centre module and two cross- deck pieces. Each hull is a two-person lift, as is the gondola, and the other components need only one person. The hulls and gondola are attached to the cross-beams using bolts that have large, spring-loaded plastic knobs on the top that are tightened by hand. At the moment, working on the battery terminals requires the use of a spanner, but ASV is looking for a solution that will eliminate even that. The idea, Daltry says, is to get to the point where a pair of hands is all that is needed for almost all assembly/ disassembly tasks, although he admits that installing sensors is likely to require more than that. Typically, sensors are bolted to a flange at the bottom of the deployment pole. Robustness was also a key requirement to enable the C-Cat 3 to withstand any rough handling. “Each hull is like a canoe,” Daltry says. “You can run it over whatever you want to and not hurt it.” While the gondola is not intended to rest on the water, it does have some buoyancy of its own, the centre of which is carried far forward to prevent the boat from nosediving if it encounters a big wave head-on. This design is well-proven on sailing catamarans and fast ferries. There is also extra payload volume in this forward area, accessible via a hatch. Aft of this is the 19 in rack area in the mid- section, with ASV’s control, comms and navigation electronics in the stern section. The company’s naval architects have prior sailing catamaran design experience, so they had a good feel for what the hull form should be. They didn’t put a lot of time and effort into optimisation (using computational fluid dynamics packages) of the hull form, as any gains in efficiency were limited by the manufacturing technique used – the hulls are made from roto-moulded polyethylene for robustness and low cost, which took priority. Daltry qualifies this by adding that the C-Cat 3 is relatively quick for its length. “We have had 10 knots in trials,” he says. “We have limited it to 8 knots just to try to preserve the batteries in case customers get a bit stick happy! Its performance is slightly better than we anticipated.” Sea state limits In terms of the maximum sea state in which the C-Cat 3 can operate, Daltry says the limit hasn’t been found yet, largely because the opportunity to try it out in severe weather has not presented itself to date. “It’s not designed to go out in really big waves. It’s hard to make a catamaran self-righting, as you can imagine, February/March 2018 | Unmanned Systems Technology Dossier | ASV Global C-Cat 3 USV ASV designs and builds its own control electronics and houses them in a sealed container mounted in the rear section of the gondola (Courtesy of ASV Global) Southampton University’s C-Cat 3 in a mild chop. With modern sonars, the boat has proved capable of producing good data in various sea states (Courtesy of ASV Global)