DARPA launches NOMARS ship USX-1 Defiant

DARPA’s No Manning Required Ship (NOMARS) program has built a ship designed to operate autonomously for long durations at sea. This may be the first US Navy ship designed from the keel up for autonomous operations.

The prototype Unmanned Surface Vessel (USV), USX-1 Defiant, is a 180-foot, 240 tonne ship that will undergo extensive in-water testing, both dockside and at sea. Construction of USX-1 Defiant by SERCO North America at Nichols Brothers Boat Builders in Freeland, near Seattle in Washington State, was completed in February 2025 and she is scheduled to depart for a multi-month at-sea demonstration in the northern spring of 2025, according to DARPA.

The NOMARS program aims to challenge the traditional naval architecture model, designing a seaframe from the ground up with no provision, allowance, or expectation for humans on board, it adds. Previous US Navy USVs such as USV Nomad and USV Ranger took part in a trans-Pacific cruise in late-2023; these were crewed ships which had been converted for autonomous and optionally- crewed operations.

USV Ranger test-fired an SM-6 missile using a four-pack Mk41 Vertical Launch System (VLS) launcher in 2021. Due to USX-1 Defiant being covered in tarpaulins, presumably to conceal her sensors and armament, it’s impossible to say whether or not she is armed with a single 4-cell VLS, like USV Ranger, or has more of them – or none.

By removing the human element from all ship design considerations, the program intends to demonstrate significant advantages, to include: size, cost, at-sea reliability, greater hydrodynamic efficiency, survivability in high seas and survivability against adversary action through stealth considerations and tampering resistance.

Last December DARPA announced it had successfully tested uncrewed Refuelling at Sea (RAS) whilst under way. Also in December, the US Navy announced it had completed its final continuous 720-hour, or 30 day, test of potential propulsion systems for a USV. Some four diesel engines teams were tested in six separate configurations based on vendors’ future USV designs: the Caterpillar 3512 and 3516; Cummins QSK95 teamed with an ABB AMG generator; MTU with the 20V 4000 M93L; and Cummins again, with its QSK60 engine and QSM11 diesel generating set. DARPA hasn’t said yet what sort of propulsion system the USX-1 Defiant has.

With scaled production, NOMARS has the potential to efficiently and cost-effectively deliver a distributed USV fleet, says DARPA.