Serco’s DARPA 'Defiant' offers autonomous surveillance and endurance at sea
Serco is the designer, integrator, and lead contractor for the No Mariner Required Ship (NOMARS) 'Defiant' - a Medium Unmanned Surface Vessel (MUSV)-class autonomous platform, funded by the US Defense Advanced Research Projects Agency (DARPA).
Bringing robotic and autonomous systems/artificial intelligence (RAS/AI) to the fore, Serco’s Defiant offers enhanced maritime capabilities across a range of military and civil operations.
By performing critical tasks such as long endurance intelligence, surveillance, and reconnaissance with precision and efficiency, Serco Defiant reduces the risk to Navy personnel and platforms, while operationally releasing crewed vessels for higher priority missions.
With the combination of advanced sensor technologies, AI enabled data analytics, and demonstrated marine autonomy, the Defiant is positioned to revolutionise Distributed Maritime Operations and provide real-time information and “on-station” response to threats.
Offering the potential to be deployed for a range of naval and para-military missions, including Search and Rescue operations, environmental monitoring, Anti-Submarine Warfare, and Humanitarian Assistance and Disaster relief, the Defiant can be tasked to operate autonomously or in company with crewed vessels, providing flexibility and versatility across the full gamut of maritime operations.
The Defiant represents a radical shift away from conventional ship design practices, toward the creation of robust, reliable, long-endurance, autonomous and adaptive maritime platforms.
The Defiant design focuses on the idea of an engineering transformation, reimagining traditional vessel design and engineering operations and maintenance philosophies, which not only pushes the boundaries of innovation, but offers the potential to expand and redefine Australia's enhanced lethality surface combatant fleet.
The wide-scale adoption of long endurance autonomous platforms like the Defiant concept will provide military planners greater flexibility when developing plans and response options, offering new and asymmetric pathways to delivering evolving warfighting concepts, harnessing the power of RAS/AI to deliver "impactful projection" across Australia's maritime approaches, and contribute to maintaining sovereignty and security in the region.
Defiant demonstrates drastically improved mission endurance and reduced cost per mission hour over legacy platforms.
- No human crew required onboard while the vessel is at sea, including refuelling and port entry/exit.
- Capable of operating for up to 12 months at sea without human intervention.
- 50-meter long, 300 tonne class vessel in the size range of the US Navy’s MUSV program.
- Can carry upwards of 55 tonnes of mission payloads at tactically relevant range.
- Can transit over 7,000 nautical miles without replenishment.
- Reduced cost per mission hour over legacy platforms.
USX-1 Defiant Christened, Marking Serco’s Breakthrough into Autonomous Maritime Operations
On 11 August 2025, the christening of the USX-1 Defiant took place at Everett Ship Repair in Everett, Washington, signalling a pivotal moment in Serco’s future of naval architecture and autonomous operations.
The USX-1 Defiant represents a radical departure from traditional ship design, conceived from the keel up with no provision or expectation for human crew. This “clean-sheet” approach aims to deliver unprecedented advantages in size, cost, at-sea reliability, hydrodynamic efficiency, and survivability, ultimately enabling a new class of highly capable and cost-effective unmanned surface vessels (USVs).
Following its christening, the USX-1 Defiant will begin an at-sea demonstration of its reliability and endurance. The program aims to validate the core NOMARS concept, paving the way for significant advancements in unmanned naval capabilities.
Follow updates on the Defiant’s progress online at http://www.darpa.mil/nomars.
The USX-1 Defiant saw a successful launch earlier in 2025 - the milestone representing a significant leap in autonomous ship design and operational philosophy, pushing the boundaries of what is possible in naval technology.
