The Defense Advanced Research Projects Agency (DARPA) and the company Serco have successfully completed the construction of the first No Manning Required Ship (NOMARS) prototype, marking a significant advancement in autonomous naval technology. 

The initiative aims to enhance the operational capabilities of the U.S. Navy with a fleet of medium-sized unmanned surface vessels capable of transporting payloads without human intervention.

The newly developed 55-meter-long vessel, named USX Defiant, is set to undergo a series of rigorous dockside and open-water trials starting this spring. 

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The objectives of the NOMARS programme include improving hydrodynamic efficiency, ensuring reliability at sea, and enhancing survivability through stealth features and tamper resistance. By eliminating the need for onboard personnel, the programme introduces a fundamentally different approach to ship design and functionality.

In December 2024, DARPA achieved a key milestone by conducting its first at-sea refueling test under the NOMARS initiative. This test demonstrated the ability of unmanned vessels, such as the Ranger and Mariner, to execute critical operations, including passing, probe connection, and fuel transfer. 

The success of this demonstration validated the potential of autonomous ships to operate independently over extended missions.

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Serco was contracted in 2022 to design the USX Defiant using software-generated hull concepts ranging from 170 to 270 metric tonnes. The final build settled at 210 metric tonnes, incorporating hybrid power generators and a cruising speed of 28 km/h.

Serco has indicated that the core Defiant USV, excluding mission-specific add-ons, has an estimated cost of $25 million. The U.S. military classifies medium USVs as those under 200 feet in length and 500 tonnes in displacement, positioning the Defiant within this category.

DARPA’s released images highlight key design features of the Defiant, including a slender hull and a central mast equipped with commercial navigation radars and antennas. Additionally, a smaller mast is located at the bow, enhancing communication and sensor capabilities. 

The vessel also features large open deck spaces suitable for modular payloads, including standard shipping containers that could house various mission systems.

One potential future application for the Defiant is weapons integration, with models showing the possible use of BAE Systems’ Adaptable Deck Launching System (ADL). This modular launcher is capable of firing a range of missiles, including surface-to-air, anti-ship, land-attack, and anti-submarine weapons.

As trials progress, the success of the programme could pave the way for larger, more capable unmanned vessels.

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