HII has completed a US Defense Innovation Unit (DIU) prototype program for the Watcher small unmanned surface vessel (sUSV), demonstrating the platform’s autonomous capabilities and positioning it for potential production.
The Watcher is based on HII’s ROMULUS-25 unmanned surface vessel and was developed in partnership with MetalCraft Marine under DIU’s Production-Ready, Inexpensive, Maritime Expeditionary (PRIME) initiative. HII delivered two autonomous vessels in December 2025 for testing focused on smaller-form-factor autonomous surface vessels for the US Marine Corps.
According to DIU, the Watcher demonstrated its suitability for sUSV interceptor missions, including autonomously transiting hundreds of miles through contested waters, loitering in an assigned operating area while monitoring for surface threats, and sprinting to intercept a noncooperative maneuvering vessel.
The two ROMULUS-25 vessels completed a series of at-sea assessments covering autonomous mission behaviors, seakeeping, performance and operations in degraded environments. The vessels also participated in contractor demonstrations and government-led autonomy assessments.
The Watcher uses HII’s Odyssey Autonomous Control System (ACS), a modular open systems architecture designed to support autonomous navigation, mission planning, collaborative behaviors and multi-domain operations. The system also enables AI-enabled contact recognition and identification, as well as edge-based decision-making.
The ROMULUS-25 is a high-speed interceptor capable of carrying payloads of up to 1,000 pounds (454 kg) and operating at ranges of up to 1,000 nautical miles (1,852 km).
HII said the successful completion of the PRIME prototype met the program’s key technical objectives and success metrics, supporting a potential transition to production through Other Transaction Authority prototype agreements.
"This milestone is another example of HII’s strategy to rapidly transition innovative technologies from concept to operational capability," said Duane Fotheringham, president of the Unmanned Systems group within HII’s Mission Technologies division.
"As demand for autonomous systems continues to grow, HII remains focused on delivering proven, mission-ready autonomous solutions that strengthen naval readiness and provide our customers with greater operational flexibility."
"This milestone is a significant accomplishment for the entire MetalCraft team and a strong validation of what can be achieved when our experienced boatbuilders combine their expertise with HII autonomy capabilities. The Watcher was engineered and built to deliver the speed, seakeeping, strength and reliability demanded by this mission. Successfully completing the government-led autonomy, seakeeping, performance and degraded-environment assessments confirms the quality of the aluminum platform and the discipline behind its design and construction. MetalCraft has built its reputation on high-performance aluminum vessels that perform when needed most, and this milestone positions the Watcher for the next step, from successful prototype to production," Mike Reed, General Manager of MetalCraft Marine, stated.
The Watcher and ROMULUS-25 are part of HII’s broader portfolio of autonomous maritime systems, which also includes the REMUS family of unmanned underwater vehicles and the Odyssey autonomy system. Together, the systems are intended to provide autonomous capabilities across surface and underwater operations.