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25 to use a preconfigured survey tool like the C-Cat 3 than rely on manned boats available for hire locally or the inflatables commonly used in this industry. With the University of Southampton as the launch customer, and a second customer signed up and others in the works, the C-Cat 3 is the first of ASV’s boats that will be built in batches. The company is now constructing its first batch of five and hopes to sell at least that many this year. It also keeps one for itself that it leases out and uses in customer demonstrations, of which it has done several to find out how it works in particular use cases. These range from surveying stretches of the River Thames, around the bottom of bridge pilings, and small surveys in reservoirs, inlets and harbours. Catamaran characteristics There are several reasons for choosing a catamaran configuration, Daltry says, one of the most important being the volume available for payload within a compact overall length. “We wanted to be able to carry up to 4U of 19 in rack modules,” he says. “A lot of the topside amplifiers and electronics for survey systems are in 19 in rack modules. We looked at the market and no-one else is able to do that.” He qualifies this by acknowledging that sonar manufacturers have responded to the new wave of small platforms, offering sets with very compact topside equipment that draw very little power. However, he also points out that many survey companies have made major investments in their existing systems, which meet International Hydrographic Organisation standards and which they are not keen to replace in the near future. The ability to fit this equipment into the C-Cat 3 was one of the key things that ASV wanted to deliver. “That meant we needed the volume to hold that stuff, and we wanted to make sure we delivered the survey performance,” Daltry says. “The catamaran just happened to give us the right combination of attributes. “They are relatively efficient from a drag perspective with the Froude number [used to determine the resistance of a partially submerged object moving through water] we are running at. It gives you a very clear payload area and the ability to mount sonar heads under the cross-deck.” He adds that the flat underside of the cross-deck is also a very convenient place to mount different or additional devices, giving ample scope for future development. Besides all the customer equipment making up the payload, the gondola also contains the boat end of ASV’s standard control system, with a software plug-in for the C-Cat 3, and all the navigation and comms gear. The two hulls are identical and can be swapped left to right if necessary. Each contains only a battery, a motor ASV Global C-Cat 3 USV | Dossier Unmanned Systems Technology | February/March 2018 The C-Cat 3’s hulls are identical, each containing a battery, motor controller and thruster. Hulls and gondola are attached to aluminium cross-beams with hand-tightened bolts (Courtesy of ASV Global)