n. An autonomous or remote-controlled boat.
2016
Sea Hunter‘s size and cost open an intriguing new niche in naval operations. Imagine swarms of small, inexpensive, and above all expendable unmanned craft scouting ahead of or escorting traditional task forces. If the roboats get blown up, it costs no lives and relatively little treasure. If the roboats survive, their sensors provide invaluable intelligence to the fleet, and intelligence can win wars.
2015
The unique, unmanned operation of such Roboats allows investigation, interrogation and observation at a significant distance up to 10 km from a mother ship depending always on antenna height and the range can be extended using satcoms.
2014
Robots are at their best when doing jobs humans shouldn't. Sometimes, this job means doing boring work, like slowly crossing the ocean recording data. Other times, this means looking for explosives under the water. The U.S. Navy’s Unmanned Influence Sweep System, or UISS, is a robot boat (or roboat, if you will) meant to perform the latter.
1999 (earliest)
I have used a GPS "Garmin mod. GPS25-LVS" in a project called "ROBOAT", a robotic model boat that sails with the help of GPS and electronic compass.
Researching this word gave me inordinate pleasure, not only because it's pronounced the same as rowboat, a vehicle which is effectively its functional opposite, but also because we exist at a time and place where an entity with the name Superyacht News can exist (see the 2015 citation). "O brave new world, that has such people in't!"