HII expands ROMULUS USV production

HII is expanding production of ROMULUS, its large uncrewed surface vessel (USV). US requirements for USVs are increasing the size of the vessels, will Europe follow suit?

By Sam Cranny-Evans, editor of Calibre Defence, published on April 22, 2026.

HII (NYSE: HII) is expanding its production of the ROMULUS 151 USV with four hulls being added to its programme. One ROMULUS 151 is already in build, the April 21 press release explains, so five will now be produced.

The hulls will be built by the Breaux Brothers Enterprises in Louisiana and the expansion, “signals a rapid shift toward initial production,” the release states. HII has built a consortium of partners around its ROMULUS USV, including Applied Intuition in a strategic MoU also announced on April 21.

Together, the two companies will collaborate on advancing Applied Intuition’s Warship OS™. According to the press release, Warship OS an AI-defined operating system that “integrates data and AI from bow to stern.” It is designed to enable scalable autonomy, the release states.

The reference here is likely to the challenges of getting a vessel to autonomously navigate on the open sea. It should be quite straight forward, but there are many rules that a ship would have to comply with. It can and has been done. But doing it at the scale and coordination required by a navy is another matter.

Other partners on the ROMULUS project include BEIER Integrated Systems, Shield AI, C3.AI, and Incat Crowther. Further abroad, HII is building a ROMULUS 190 in Australia, which is being built by Incat Crowther. The vessels use Odyssey, a maritime autonomy stack from HII, as well as Hivemind from ShieldAI. So, with at least three big AI-enabled products, it seems that HII is focusing heavily on the autonomy aspect of the vessel.

Expansion before contract: What is happening in US procurement?

You may have noticed that HII and Saronic are expanding production of their large USVs without a contract. Blue Water Autonomy made similar commitments when it partnered with Damen in February 2026. This is unusual for defence companies; few will risk their own capital to build platforms that may never be bought. They usually wait for a government requirement to build a prototype or concept, and only once a contract has been awarded do they commence development and production.

This approach is understandable. Hundreds of millions of dollars have been spent on platforms on both sides of the Atlantic for programmes that were cancelled before contract.

However, the US Department of War has reformed its acquisition process. It is increasingly prioritising speed of delivery over other metrics like cost and capability. It is, according to some from industry, willing to accept 70% or 80% solutions that are ready now, rather than 100% solutions that could be available in a decade. As Secretary of War, Pete Hegseth, said in a November 2025 speech, “The defence acquisition system as you know it is dead.”

In that speech, he warned traditional primes that if they did not use their own capital to fund development and start production early, they would “fade away.” This is why both primes like HII – which builds the Gerald R. Ford Class aircraft carrier – is expanding production ahead of contract and using similar investment strategies to new players like Saronic.

Calibre comment: Will Europe follow suit with larger USVs?

The US need for larger USVs is driven by the ocean-going nature of its requirements. Programmes like the US Navy’s Modular Attack Surface Craft (MASC), need ships that can survive in the Indo-Pacific. This requires long endurance and operational range, as well as an ability to withstand extreme weather and waves. Smaller craft are unable to meet these requirements and carry the large sensors needed to perform usefully in large bodies of water.

Europe, however, has not shown many signs of a demand signal for this type of vessel. It is possibly something that will be introduced – Saronic is understood to be setting up a UK entity, for example. The company could conceivably bring its large Marauder class to the UK if the demand was there. It logically follows that running complex anti-submarine warfare operations in the North Sea and North Atlantic – similarly to those that the UK recently announced – would require larger USVs. However, with much of the focus currently on restoring the traditional surface combatant fleet, it is probable that larger USVs will have to wait. In the meantime, WarDev efforts and trials are continuing, which should inform the deployment of larger vessels when they come.

The lead image shows a ROMULUS 151 in build at Breaux Brothers Enterprises in Louisiana. Credit: HII.