Sea Hunter (ACTUV)

The Sea Hunter is an autonomous unmanned surface vehicle (USV) developed under the Defense Advanced Research Projects Agency (DARPA) Anti-Submarine Warfare Continuous Trail Unmanned Vessel (ACTUV) program. Designated as a Class III Medium Displacement Unmanned Surface Vehicle (MDUSV), the vessel was designed and built by Leidos. Manufacturing was initially subcontracted to Christensen Shipyards and subsequently completed by Vigor Industrial. Christened in Portland, Oregon, in April 2016, the vessel is part of a developmental lineage of experimental ships that includes the Sea Shadow, Sea Fighter, Sea Jet, and Sea Slice. In February 2018, DARPA transitioned the development program to the Office of Naval Research (ONR).

The vessel is configured as a trimaran, featuring a central hull flanked by two outriggers. This hull design provides stability without a weighted keel, facilitating operations in shallow waters and maintaining linear trajectories, though the configuration reduces overall maneuverability. Powered by diesel engines with twin screws, the initially unarmed prototype is designed for autonomous operation. During its testing phase, a temporary, removable operator control station was installed for safety. Operationally, the vehicle relies on Sparse Supervisory Control, a system where onboard computers pilot the vessel while a human operator monitors telemetry and can assume control if required. The vehicle's autonomous navigation suite utilizes radar and optical guidance to detect and avoid obstacles. The internal compartment layout is configured to allow maintenance access but contains no crew accommodations. Future variants may be configured with armaments for anti-submarine and counter-mine roles.

Sea Hunter completed its initial open-ocean performance trials in June 2016. In summer 2017, the vessel transferred to the ONR for operational testing focused on mine countermeasures, electro-optical and infrared sensors, and submarine detection. In August 2022, the vessel participated in the multinational Rim of the Pacific (RIMPAC) exercise alongside the unmanned vessels Nomad and Ranger. The U.S. Navy plans to operationally deploy Sea Hunter and its sister ship, Seahawk (built in 2021), in 2026 as part of Surface Development Group One, establishing the Navy's first active unmanned surface vehicle division. Additionally, reports from 2020 and 2024 indicate that the People's Republic of China has commenced construction of clone vessels based on the Sea Hunter design.