Serco, DARPA Launch NOMARS USX-1 Defiant

Serco, DARPA Launch NOMARS USX-1 Defiant
The NOMARS program’s prototype vessel, USX-1 Defiant, completed construction in February 2025. DARPA photo
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NOMARS envisions a cost-effective USV concept for the U.S. Navy through a design philosophy that excludes all crewed features.

Serco launched the Defense Advanced Research Projects Agency’s No Manning Required Ship program medium unmanned surface vessel prototype, USX-1 Defiant, at Nichols Brothers Boat Builders shipyard last month in preparation for a series of trials that aim to bring a cost-effective USV to the U.S. Navy. 

From the design’s outset, the 180-foot-long, 240-ton vessel was designed without considering human habitation or protection features. According to DARPA, the NOMARS program “intends to demonstrate significant advantages,” including at-sea reliability, hydrodynamic efficiency, and stealthy features. 

“The NOMARS program aims to challenge the traditional naval architecture model, designing a seaframe (the ship without mission systems) from the ground up with no provision, allowance, or expectation for humans on board,” stated the DARPA release. 

Serco was selected to construct the demonstrator by DARPA over Leidos Gibbs and Cox in 2022. The program, originally launched in 2020, looks to design a Medium USV with unprecedented reliability and availability.

Ryan Maatta, a Marine Engineer Manager with Serco overseeing the NOMARS project, told Naval News at the annual Surface Navy Association symposium that the program’s key features include a 90% reliability at sea for a year and an autonomous refueling capability. USVs Mariner and Ranger demonstrated SERCO’s refueling capability in a test last September. Maatta also confirmed that Defiant would undergo two months of sea trials before “a very large and extensive demonstration of the vessel and its capabilities.” 

The DARPA NOMARS program has successfully launched the USX-1 Defiant, a 180’, 240-metric ton medium unmanned surface vessel designed to revolutionize autonomous operations at sea. DARPA Photo

“What we’re trying to prove out here is the feasibility of completely unmanned vessels vs partially unmanned. This is a much larger form factor, more than anyone has done. A completely unmanned vessel, rather than an optionally manned vessel,”

Ryan Maatta, Marine Engineer Manager at Serco

While the USV’s deck was covered by a tarp in photos released by DARPA, Serco’s concept models include one BAE Adaptable Deck Launcher and a container. The company’s Large USV concept, which Maatta described as the Second World War-era destroyer escort of the future, comes equipped with four Adaptable Deck Launchers for a complement of 16 strike-length Mark 41 missile cells. 

Defiant is unique in this regard, as previously tested USVs such as Nomad and Ranger were retrofitted offshore vessels converted for autonomous operations. Sailors were embarked on the U.S. Navy’s Ghost Fleet Overlord during its 2023 Indo-Pacific voyage to ensure systems ran accordingly. Maatha highlighted that the removal of berths, galleys, and other facilities provides a “much larger payload fraction” on Defiant

“One of the historic problems with unmanned systems is, they promise to keep sailors or pilots safe, but they don’t tend to be less expensive than their manned counterparts. We really worked to change the philosophy and operating principles so that this is much less expensive to do the same mission as a manned platform,” said Maatta in a Naval News interview. SERCO has claimed that it has the capabilities required to mass produce and maintain vessels similar to NOMARS and its LUSV concepts.

The NOMARS program and Defiant come amid increased calls from American policymakers and combat commands for cost-effective USVs, specifically in a potential Chinese invasion of Taiwan. Admiral Samuel Paparo, head of the U.S. Indo-Pacific Command, has detailed his use of the vessels in Hellscape, which aims to flood the Taiwan Strait with drones.

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