New information reveals that the Chinese Navy (PLAN) is testing its uncrewed submarines on Hainan in the South China Sea. The two underwater drones, by far the world’s largest, have not been publicly revealed by Beijing, H I Sutton reports in Naval News.
In the West, defence firms are rushing to build extra-large underwater vehicles. Navies are testing them and starting to explore how they bring new capabilities, and operate alongside other naval vessels. Meanwhile, China is years ahead in terms of both investment and ambition.
China is testing new underwater drones which literally and figuratively dwarf even the largest Western designs. At over 40 meters long they make the U.S. Navy’s Orca XLUUV (extra-large uncrewed underwater vehicle) look like a bath toy.
Naval News first revealed the existence of one of these drones, then cautiously described as a submarine, in January. Now we have significant new information. We can now be confident that the craft, the size of some country’s regular submarines, is uncrewed. What is more, it is not alone. China has built two similar sized drone submarines and is testing them together in the South China Sea.
Secret Testing In South China Sea
The two new uncrewed submarines are being tested in the waters around Hainan in the South China Sea. They are temporarily based in Gangmen Harbour west of the main naval base at Sanya. That is where Chinese nuclear submarines, aircraft carriers, and other Chinese extra large uncrewed underwater vehicles have been observed. The XLUUVs, such as the AJX002 minelayer, can be kept on the quay and lifted in and out of the water by crane. However these latest underwater drones, being much larger, are being accommodated differently.
Instead they are being kept in two floating docks. This alleviates the challenges of putting them in and out of the water. It also removes the complication of controlling them in busy ports where they pose a potential hazard to ships. The floating dock can sail to sea and release or retrieve them out of the way of other traffic. Two main areas of activity have been identified, one in Gangmen Harbour and the other further along the coast at Yinggezui.
Additionally the docks have provided effective cover from ship spotters who might otherwise have revealed their existence. This is reminiscent of the way in which the United States hid the Sea Shadow stealth boat in a floating dock. The arrangement adds to the secrecy of the trials.
One of the docks, Zhuan Yong Fu Chuan Wu 001 (专用浮船坞001 which means Special Floating Dock) was only built in 2024. It was launched by CSSC Guangxi Shipyard in October last year and was picking up the new uncrewed submarine in January. Since then it has sailed to Hainan where the trials have been observed.
XXLUUV – New Category Of Uncrewed Submarine?
From the manner in which they are being housed and deployed it is now clear that they are indeed uncrewed platforms. The current term used for larger underwater drones, XLUUV, doesn’t do these new vessels justice however. It was never future-proof to use ‘XL’ (Extra Large) in a designation since it was inevitable that people would soon build much larger ones. These latest types are about 10-20 times larger than what passes for an XLUUV in Europe. So possibly XXLUUV or Ultra-Large-UUV?
Their immense size isn’t just for range. It implies different capabilities and roles to existing XLUUVs. This is underscored by the fact that China is building a range of XLUUVs more akin to their Western cousins (except quicker to be weaponized). Instead these new types appear more like proper submarines. Their roles are likely to be more complex.
We can infer that they carry considerably more weapons or other payloads than other XLUUVs. A crewed submarine of that size can typically accommodate 8 heavyweight torpedoes. And without the crew to accommodate these might carry more. Thus the number of weapons will likely be dictated by cost and requirements rather than space.
More Capable Vessels
The new vessels themselves remain enigmatic. From satellite images we can determine that they are around 40-42 meters (131 -138 ft) long, do not appear to have traditional submarine sails, and have X-form rudders at the stern. Strong circumstantial evidence links one of the two vessels has been developed by 705 Research Institute, part of China Shipbuilding Industry Corporation (CSSC) which is known for weapons development.
While we can only speculate around propulsion, the way that they are housed in dry docks suggests that they do not require complex or sensitive fuel supplies such as liquid oxygen. Given their size they may have onboard diesel generators, and/or huge quantities of lithium-based batteries. There will naturally be speculation that they may have a form of nuclear propulsion, like the Type-041 Zhou class, but there is currently no evidence of this.
A larger vessel like these can also have a much more capable sensor suite. This is likely to include larger and more powerful sonar, more comparable to those on regular submarines. Without the crew they will need the latest advances in artificial intelligence to process the data.
Implications For The West
It seems inevitable that uncrewed submarines will increasingly encroach on the domain of traditional submarines. They are unlikely to be as powerful, or flexible, but they will bring new dimensions to naval combat. The balance of risk-reward may shift to favour more aggressive strategies. This is a new world which China seems much more willing to embrace, and is consequently getting ahead in.
It has long been a working assumption that Chinese naval technology is decades behind the West. And that Chinese engineers are not inclined to innovate. These attitudes have been shown to be outdated, yet they persist. These new XXLUUVs are thus yet another wake up call for Western planners.
