Royal Navy Unveils 12-Metre Uncrewed Submarine Named Excalibur
In a ceremony at HM Naval Base Devonport on 15 May, the Royal Navy unveiled its first uncrewed submarine, XV Excalibur. The 12-metre vessel was introduced in front of 200 guests, including senior officers, US and Australian naval representatives, and cadets. Commodore Marcus Rose said the naming of Excalibur is “a significant milestone for the Royal Navy,” and that the upcoming trials will rapidly build understanding of how to operate such systems. The name “Excalibur” was chosen for its heritage and symbolism. In legend, Excalibur is King Arthur’s magic sword (a symbol of power and protection).
Excalibur is a new uncrewed submarine developed under Project CETUS, an experimental programme launched in 2022. It was created through a joint effort by the Royal Navy’s autonomy and innovation teams, Defence Equipment and Support (DE&S), and industry partners. The vessel was built by UK company MSubs in Plymouth and was first launched in February at Turnchapel Wharf. Officially known as an Extra-Large Uncrewed Underwater Vehicle (XLUUV), the Royal Navy submarine Excalibur features advanced sensors and a sleek, stealthy design. Since its delivery to the Royal Navy, it has undergone a series of harbour and sea acceptance trials at the Devonport naval base. In its current setup, this uncrewed underwater vessel can operate at sea for up to five days.
vessel will be called XV Excalibur. (Picture: LPhot Unaisi Luke/Royal Navy)
It will try out concepts like hunting enemy submarines and monitoring the seabed, helping the Navy learn how to use uncrewed subs in real operations. Over the next two years, Excalibur will undergo extensive sea trials. Although not built for combat missions, the Royal Navy submarine Excalibur will join the new Fleet Experimentation Squadron, managed by the Disruptive Capabilities and Technologies Office. It will work alongside the experimental surface ship XV Patrick Blackett as a test platform for new maritime technologies. Excalibur will support trials focused on intelligence, surveillance, and reconnaissance (ISR), and test special sensors or payloads in challenging environments.
Combining advanced technology and real-world testing, the Excalibur uncrewed underwater vessel helps the Navy develop a fleet of crewed and uncrewed ships. Its use in testing XLUUV capabilities in realistic conditions will help shape the future of undersea operations and support the UK’s goal of staying ahead in modern naval defense.