DARPA Christens U.S. Navy's First Fully-Unmanned Oceangoing Ship
Developed and built outside of NAVSEA, the Defiant will become a Navy vessel after testing

The Defense Advanced Research Projects Agency (DARPA) has christened its fully unmanned warship prototype, the No Manning Required Ship (NOMARS).
DARPA pioneered the U.S. military's unmanned-vessel efforts with the launch of the ACTUV / Sea Hunter system in 2016. The much larger NOMARS design evolved in parallel with the Navy's crewboat-influenced systems, variously named Ghost Fleet Overlord, MUSV, FUSV and (most recently) MASC.
NOMARS is designed to maneuver around the U.S. shipbuilding industrial base's limitations. Its hull design has fine lines for speed, but it's simple enough to build at any Tier III shipyard with room for a 180-foot boat of 240 tonnes displacement, DARPA says. That specification means that many workboat and yacht yards could bid, so the ship could be built at scale without the wait times of the overburdened Tier I prime contractors. (The Defiant prototype was built at Nichols Brothers Boat Builders, a well-regarded yard not previously known for warship construction.)
When it comes to capability and concept of operations, Defiant is a sea truck for deck-mounted equipment. It has open deck space for a variety of containerized payloads, to include up to 16 Mk 41 vertical launch system missile cells.
The vessel's first purpose, though, is to demonstrate truly unmanned, long-distance operation. Without the need to support and protect sailors, the ship is skinnier, lighter, cheaper and more expendable. The concept is to jump past the "optionally manned" configurations that the Navy has pursued and move straight to zero-crew construction. Mechanical reliability is among the biggest hurdles for high endurance unmanned systems, and DARPA wants Defiant to demonstrate up to 12 months of operation without human intervention.
Sneak peek: Our No Manning Required Ship (NOMARS) Defiant #USV is designed to operate for up to a year at sea without human intervention. In-water testing is preparing it for an extended at-sea demonstration of reliability and endurance. Stay tuned for more news soon! pic.twitter.com/5mPQfzBc2Z
— DARPA (@DARPA) July 18, 2025
“Defiant is a tough little ship and defies the idea that we cannot make a ship that can operate in the challenging environment of the open ocean without people to operate her,” said NOMARS Program Manager Greg Avicola, during the ceremony. “While relatively small, Defiant is designed for extended voyages in the open ocean, can handle operations in sea state 5 with no degradation and survive much higher seas, continuing operations once the storm passes. She’s no wider than she must be to fit the largest piece of hardware and we have no human passageways to worry about."
The Navy's unmanned R&D office, PMS 406, will be taking possession of the Defiant after initial at-sea demonstrations. It will be the service's first and only fully unmanned oceangoing vessel.