Serco and DARPA mark official launch of USX-1 Defiant NOMARS demonstrator

Government service supplier Serco announced on 13 August 2025 the official launch of the USX-1 Defiant, its demonstrator unmanned surface vessel (USV) for the No Manning Required Ship (NOMARS) programme, by the Defense Advanced Research Projects Agency (DARPA).

The launch ceremony took place at Everett Ship Repair in Everett, Washington, following a christening ceremony on 11 August. The USV was actually first launched at Nichols Brothers Boat Builders shipyard in Freeland, Washington, in March 2025.

The NOMARS programme 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. By removing the human element from all ship design considerations, the programme intends to demonstrate significant advantages, to include: size, cost, at-sea reliability, greater hydrodynamic efficiency, survivability to sea-state, and survivability to adversary actions through stealth considerations and tampering resistance.

Following its launch the USX-1 Defiant USV, which is 180 ft (54.9 m) long and displaces 240 tonnes, will begin a multi-month at-sea demonstration of its reliability and endurance. The programme aims to validate the core NOMARS concept, paving the way for significant advancements in unmanned naval capabilities.

After completing the at-sea demonstration, Defiant will be turned over to the US Navy’s Unmanned Maritime Systems Program Office (PMS 406). Upon transition to PMS 406 Defiant will be the US Navy’s first solely autonomous (as opposed to hybrid manned/unmanned) medium USV.

“Defiant marks a first in naval ship design and ushers in an exciting new stage for the NOMARS programme and the US Navy,” Anthony Kirby, Serco Group’s chief executive, was quoted as saying in a company press release. “We are incredibly proud to have played our part in developing genuinely groundbreaking new capabilities for the navy in vessel autonomy and at-sea refuelling.

“This watershed is the first time a ship has been designed entirely without human crew members in mind, a significant step towards the US Navy’s ambition of a fleet of USVs capable of operating in contested waters and other dangerous environments without putting the lives of human sailors at risk,” Kirby added.

DARPA selected Serco over Leidos Gibbs and Cox to construct the NOMARS demonstrator in 2022.

Defence is a large and growing part of Serco’s portfolio, accounting for over 80% of the company’s order intake in the first half of 2025.