n. An autonomous or remote-controlled boat.
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.
—Sydney J. Freedberg Jr., “DSD Work Embraces DARPA’s Robot Boat, Sea Hunter,” Breaking Defense, April 07, 2016
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.
—“Is Hydra a Spooky Looking Jetski?,” Superyacht News, February 28, 2015
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.
—Kelsey D. Atherton, “Navy Wants A Minesweeping Robot Boat To Protect Their Fragile Ship,” Popular Science, November 07, 2014
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.
—Riccardo Rocca, “GPS” (reply), comp.robotics.misc, December 09, 1999
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!"