The UK Submarine Delivery Agency (SDA) has invested 6.68 million pounds ($8.8 million) to begin trials of the Royal Navy’s CETUS extra-large uncrewed underwater vehicle (XLUUV).
The contract, awarded to England-based MSubs, will validate autonomous undersea operations and evaluate the submarine drone’s payload capabilities for future military applications.
The company will carry out the work at its facilities in Plymouth and nearby sea ranges through 2028, according to UK Defence Journal.
The SDA said the deal was awarded directly to MSubs under the Procurement Act 2023, citing the company’s role as the sole developer of CETUS.
The agency added that no other UK supplier possesses the technical expertise required to safely operate the platform during trials without increasing costs, delays, or technical risks.
The CETUS XLUUV
Formally designated as the XV Excalibur in May 2025, CETUS is the largest underwater drone inducted into the Royal Navy.
The 12-meter (39-foot) experimental platform operates with the service’s Fleet Experimentation Squadron under the Disruptive Capabilities and Technologies Office, supporting the development of future autonomous undersea solutions.
It weighs approximately 17 tonnes (37,479 pounds) and features a hull sized to accommodate a standard shipping container.
CETUS also has an operational range of 1,000 miles (1,609 kilometers), can sail for up to five days straight, and is designed to integrate additional load and power supply if needed.
During the vessel’s christening last year, Underwater Battlespace Capability Deputy Director Commodore Marcus Rose described the program as “a significant milestone,” saying the trials would help the Royal Navy “rapidly develop our understanding of operating uncrewed vessels of this size underwater.”
Following the initial trial phase, the SDA plans to open future contracts covering platform operations and payload development to broader competition.
