DARPA Begins Phase Two of ‘Defiant’ Unmanned Ship Development

The US Defense Advanced Research Projects Agency (DARPA) has selected Serco Inc. to provide a design for the second phase of the No Manning Required Ship (NOMARS) project.

NOMARS will be a new generation of medium unmanned surface vessel that can perform with “unprecedented reliability and availability” as it carries waterborne payloads. 

The vessels created through the program are intended to conduct underway replenishment in all temperatures, weather, and sea conditions with no human maintenance and or crew requirement.


In phase one of NOMARS, Serco developed a new Design Space Exploration (DSX). The software generated millions of ship designs to “meet a diverse set of performance objectives and constraints.”

Through DSX, Serco created a set of concept designs ranging from 170 to 270 metric tons (170,000 to 270,000 kilograms) and refined it to a single ship dubbed the “Defiant.”

In phase two, the firm will finalize the design, construct the vessel, and conduct a series of tests before deploying it in a three-month demonstration.

“NOMARS plans to demonstrate a next-generation completely unmanned ship that will enable entirely new concepts of operations,” DARPA Tactical Technology Office Program Manager  Gregory Avicola said.

“We will enable methods of deploying and maintaining very large fleets of unmanned surface vessels that can serve as partners, across the globe, for the larger crewed combatants of the U.S. Navy,” he continued.

Serco is collaborating with Beier Integrated Systems LLC, Caterpillar, DRS Naval Power Systems Inc., ICE FLOE LLC, Metron Inc., Submergence Group LLC, and Thrustmaster of Texas Inc on the project.

The Defiant

Once completed, the Defiant will be the first of its kind. It will be integrated with podded propulsors, hybrid power generators, and high-capacity batteries, effective for tactical and logistical functions.

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The 210-metric ton (210,000-kilogram) vessel will run at approximately 15 knots (17 miles/27 kilometers per hour).

The Defiant’s major system components will be modularized, meaning the ship will easily be repaired using parts typically available in international yards, maximizing its lifetime at sea.