Role & capabilities
- Naval autonomy research
- Modular mission carriage
- Primary domain
- Sea surface
- System type
- Uncrewed surface vessel
- Developer / manufacturer
- Serco-led team / DARPA
- Origin / production countries
- United States
- Other names
- USX-1 Defiant; NOMARS
- Variants / configurations
- Not distinguished in reviewed sources
- Operators / programme customers
- DARPA / US Navy-supported trials
Evidence & current status
Delivered experimental vessels remain distinguished from operational fleet acceptance and future production programmes.
Defiant is the demonstrator for DARPA's No Manning Required Ship programme. Serco leads the industrial work on a vessel designed around machinery and mission needs without normal onboard accommodation. The programme investigates whether this approach can support reliable, sustained uncrewed activity at sea.
DARPA documented the ship's christening in August 2025 and its initial long-distance open-ocean transit the following month. The programme's March 2026 update says the vessel underwent engineering changes during the winter and returned to the water for acceptance trials of navigation autonomy and machinery-control software improvements. This makes it an active test programme, not a proven year-long deployment or an accepted production warship.
The published long-endurance objective must be distinguished from demonstrated voyages. DARPA describes a design aspiration of up to a year without human intervention; the public trial log instead records individual passages, port activities and system improvements. Similarly, the stated sea-state capability is a design claim rather than a guarantee of unchanged performance with every possible payload. The profile retains those distinctions so that later measured endurance, reliability results and Navy transition decisions can be added without rewriting an assumed service history.
Sourced specifications
Figures apply to the named configuration. Maximum values are not guaranteed operating performance.
| Specification | Reported value | Context & source |
|---|---|---|
| Configuration | Experimental vessel designed without onboard crew accommodation | Published programme baseline; not a generic figure for other USVs. Source |
| Hull / propulsion | Not established in the reviewed public sources. | Public evidence gap. No estimate or neighbouring variant value has been substituted. Source |
| Dimensions | 180 ft length | Published programme baseline; not a generic figure for other USVs. Source |
| Displacement / mass | 240 metric tonnes lightship | Lightship mass, not loaded displacement. Source |
| Payload | Not established in the reviewed public sources. | Public evidence gap. No estimate or neighbouring variant value has been substituted. Source |
| Endurance | Up to one year without human intervention: design objective | Not a demonstrated continuous deployment. Source |
| Range | Not established in the reviewed public sources. | Public evidence gap. No estimate or neighbouring variant value has been substituted. Source |
| Speed | Trial speed approached 20 knots | September 2025 test observation; not a certified maximum. Source |
| Sea state / environment | Sea state 5 operation advertised by programme | Design claim; survival in higher seas is not equivalent to full mission performance. Source |
| Sensors | Not established in the reviewed public sources. | Public evidence gap. No estimate or neighbouring variant value has been substituted. Source |
| Communications / control | Not established in the reviewed public sources. | Public evidence gap. No estimate or neighbouring variant value has been substituted. Source |
| Launch / deployment | Not established in the reviewed public sources. | Public evidence gap. No estimate or neighbouring variant value has been substituted. Source |
Documented milestones
Initial ocean transit reported
DARPA reported completion of the ship's first open-ocean passage.
Read the announcementShip christened
DARPA documented the Defiant demonstrator before extended sea trials.
Read the announcement
Publication history
- — Published reference update.
Suggest a correction to this entry
Follow the evidence
Source types identify who makes the claim. Programme milestones and supplier statements should be read in context.
- DARPA NOMARS test log, including March 2026 update (opens in a new tab)Programme authority
- DARPA Defiant christening and hull particulars, 11 August 2025 (opens in a new tab)Programme authority
- DARPA NOMARS development award, 22 August 2022 (opens in a new tab)Programme authority