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79 Over the following 18 months, the vehicle caught the eye of MARAD, which was interested in promoting the use of autonomy in responding to marine oil spills. That has led to the system described here, in which Sea Machines’ SM300 package – essentially an autonomy kit comprising navigation, comms, intelligence and control components – has been integrated into the MSRC’s belt skimmer vessels. The model of vessel was originally designed and built by Kvichak Marine Industries, and called the Rapid Response Skimmer (RRS); they are also sometimes referred to as Kvichak/Marco skimmer boats. They are among the most effective vessels for cleaning oil from seawater, and the filter belt assembly can scoop up a broad range of petrochemicals, from light sheens to heavy crude mixed with debris. Also, the Marco boats tend to operate in a more repetitive way than boom- towing oil clean-ups, making them even more ideal for reconfiguring as USVs. The traditional model for carrying out belt-skimming operations has two workers on the skimmer boat – one at the helm, the other operating the belt itself – working for extended periods of time. This operation is intended to be carried out fully unmanned, only requiring human technicians for launching, remote monitoring, recovery and maintenance of the USV, although initial trials were performed using one crew member on deck to intervene if necessary. As John Swift, the MSRC’s vice- president for the Atlantic Region, Interior Region and Marine Division, adds, “The MSRC’s purview for cleaning oil spills covers the waters of the entire lower 48 states, plus Hawaii and the Caribbean, so as the autonomous skimmers continue being proven, they could be operated in numerous areas around the US.” Autonomy in oil clean-ups The version of the RRS used here is 9.5 m long, with a 0.94 m draft when fully loaded. It is already widely used in oil spill operations, and has an aluminium hull, twin Yamaha outboard thrusters (each housing 70 hp gasoline piston engines), a diesel power unit and a fuel tank below deck, along with a skimming assembly with a boom-mounted electromechanical belt, and a pilot house at the rear. Rather than simply being an autopilot to control the vessel’s heading, the SM300 is a multi-system kit that consists broadly of two parts. The first is a control unit for installation on board the vessel. It includes a Siemens S7 programmable logic controller and industrial Linux computer for command processing, as well as communication and control interfaces for electric or combustion engines, electric or hydraulic steering, transmission, and an array of navigation and payload systems, all housed within a 51 x 51 x 22.5 cm IP65-rated stainless steel enclosure. The second is the GCS, which can be either a ruggedised laptop for waypoint setting, detailed remote localisation and performance tracking of the USV, or a handheld dual-joystick controller for controlling the vessel remotely, either from a nearby shore or ship or on the vessel itself. Both options can use IP radio or 4G/LTE links for nearby operations, or satellite links in the L, VSat- Ku, or Ka bands for BVLOS distances (greater than 5 nautical miles). Many of the skimmer boat’s electronics have been upgraded from standard, and several new systems added, to enable precise autonomous operations and compatibility with the SM300. Unmanned Systems Technology | October/November 2020 Sea Machines/MSRC oil-spill skimmer | In operation The MSRC has 10 Kvichak Rapid Response Skimmer boats stationed around the coasts of the US, to deploy them when and where needed MSRC’s purview for cleaning oil spills covers the entire lower 48 US states, so the skimmers could be used in numerous areas