Marking a new step toward the modernization of its capabilities, the Royal Navy announced last December that it has officially received XV Excalibur, which currently stands as the largest of its new experimental uncrewed submarines. Officially designated as an Extra-Large Uncrewed Underwater Vehicle (XLUUV), it is a system measuring 12 meters in length with a displacement of 19 tons, developed as part of the institution’s Project Cetus through a partnership between the Submarine Delivery Agency (SDA) and MSubs Ltd.
Delving into some details, it can be noted that the new submarine had already been presented in May 2025 at Devonport Naval Base (HMNB), in the presence of naval authorities from the AUKUS program. However, it still has a lengthy period of sea trials to complete, during which British personnel will have the opportunity to assess its real capabilities and become familiar with operating a system of the aforementioned size. According to current schedules, as reported in the institution’s official communication, this is expected to be completed within the next two years.
As part of this testing process ahead of its incorporation, the Royal Navy highlighted that the new unit was already able to demonstrate its capabilities during Exercise Talisman Sabre last August, with the particularity that the submarine operated in UK waters while being controlled by personnel located at an operations post in Australia, more than 16,000 kilometers away. The event itself was celebrated as a major advance within the framework of “Pillar 2” of the AUKUS partnership, which establishes the need to move forward in the interoperability of the forces of the countries that comprise it.
Later on, the Royal Navy also highlighted that XV Excalibur managed to validate the usefulness and proper functioning of its quantum optical atomic clock known as “Tiqker,” the result of development carried out by the local company Infleqtion. Specifically, it is a device that provides the submarine with precise navigation capabilities while requiring reduced external signal inputs, allowing it to remain submerged for longer periods. According to statements, this represents a novel advance that would reduce dependence on traditional microwave-based clocks, as well as on the well-known GPS system.
According to the institution: “This year’s advances herald an exciting future in which autonomous underwater vehicles and nuclear submarines will work in unison to provide exceptional underwater capability to the Royal Navy. Excalibur’s capability positions the United Kingdom as a leader in autonomous underwater technology and demonstrates the SDA’s ability to exploit the latest technologies for the benefit of national security.”
Finally, reviewing some of the missions in which it could be employed, it is worth noting that the new XV Excalibur could take part in intelligence-gathering operations, patrols of critical undersea infrastructure, and the deployment of mission-specific payloads. This would be possible thanks to its Main Payload Space (MPS) located on the upper part of the bow, complemented by other secondary spaces observable at the stern, in addition to the fact that it is equipped with hatches on both the upper and lower faces of the platform.
*Image credits: Royal Navy – MSubs Ltd.
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