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China is building a new form of drone mothership, one large enough and specially shaped and equipped, to carry drone submarines. The vessel is under construction at the Hudong-Zhonghua shipyard in Shanghai.

The size and configuration points to the carriage of full-sized uncrewed submarines. Termed XXLUUVs (extra-extra large uncrewed underwater vehicles), the ones observed in China are around 35-45 meters long.

I gave a talk on Chinese submarine and XXLUUV developments a few months ago where I suggested that the construction of special floating docks would be a leading indicator of the operationalisation of China’s uncrewed submarine program. And now here we are.

Click to Enlarge. Satelite imagery from Vantor Technologies, shared online by ‘KAROTASU’ (@type36512) on Twitter.

Mothership for Uncrewed Submarines

The vessel fills a clear need. Larger UUVs start needing port infrastructure to support them, they become much less convenient to move around. With smaller UUVs, even up to 20 meters like the AJX-002 and HSU-100 paraded in Beijing last year, they are road mobile. Truck mounted cranes should be sufficient for getting them in and out of the water making operations much simpler. With these latest, much larger XXLUUVs however, China will start to need dedicated port facilities. This mothership is likely a major part of the solution.

Until now China has been using floating docks to house the two XXLUUV prototypes being tested on Hainan. One of these docks was purpose built while the other may have been taken up from general use. These keep the vessels out of the water for maintenance and allow them to be moved well outside the port before being launched or recovered. This latter arrangement must greatly simplify testing, avoiding operating the uncrewed vessels in close proximity to other ships and port obstacles. However this arrangement also has a significant drawback: each floating dock can only carry a single XXLUUV. Or if more than one, then they both need to be placed in the water at the same time. Because the whole dock floods, there cannot be one undergoing maintenance while another is being launched or recovered.

The new mothership solves this by having a dry hangar for stowage and maintenance, and a separate lifting well for launch and recovery. Based on the relative sizes, the hangar can accommodate 2-4 XXLUUVs (or many more smaller XLUUVs), while the lifting cradle in the well deck can accommodate one at a time.

Well Deck

The well deck is at the stern, similar to on a landing ship dock (LPD), but without a bottom to it. Instead it has a cradle platform which can be lifted in and out of the water on 12 vertical jack-up arms. The well deck is around 55 meters long, which is one of the factors pointing to XXLUUVs open bottom: it’s much larger than necessary for any rescue or research submersibles.

The open well deck is a useful identification feature. The resulting keel block arrangement this creates can be seen in satellite imagery even before any sections of the actual ship have been assembled. And the jack-up arms protrude above the box-like hull.

The dry hangar is forward and positioned above the waterline. It is around 95x17 meters and several (many) decks high. The rest of the ship is built around these spaces. The superstructure is well forward, creating an overall box-like ship generally resembling a very large RO-RO ferry.

The vertical lifting cradle is unique. A conceptually identical arrangement has been seen on a proposed Chinese scientific research mothership, but on a smaller scale. Similar Jack-up legs have also become characteristic of China’s innovative mobile harbours.

An essentially similar concept, but on a smaller scale and without the covered hangar, was talked about in 2025 as part of the ‘Cold Seep Ecosystem Research Facility’, a ‘National Major Science and Technology Infrastructure’.

Other Submarine Motherships

There have been other submarines motherships, particularly during the early days in the 1900s. The French special cargo ship SS Kanguroo was built in 1912 for delivering submarines to export customers. She had a gangster inside with a bow-door opening. A few years later the the Brazilian Navy’s Ceara was built as a submarine tender with a unique pressure chamber built into the stern. Submarines could be floated in for maintenance which including pressurising the chamber to test the submarine’s hull. The weakness of these fascinating designs was that submarines quickly outgrew them, being generally too large for their hangars. In more recent times South Korea has operated the ROKS Dadohae (ASL-50) special floating dock for its special forces midget submarines. While Pakistan made a much less exotic side-lifting crane for similar sizes midget submarines at its main operating base in Karachi.

Not what she might first appear. South Korea’s ROKS Dadohae (ASL-50) is a floating dock/mothership for the country’s Italian designed Cos.Mo.S midget submarines.

Outlook

China is, as we’ve come to expect, leading the way in future naval capabilities. These special motherships will likely act as submarine tenders in port, but also transport the XXLUUVs within strike range of targets. Given that we estimate an operational range of 10,000 nautical miles, this can still be a long way from the target.

At this time the next question is whether this is a ‘grey navy’ PLAN (People’s Liberation Army Navy) hull, or a quasi-naval commercial hull operated by the shipyard. The lines between traditional navy and commercial fleets have blurred in China with full-sized drone carriers operated, ostensibly at least, by the ship building corporations. Up to a point this will be moot however, I take the construction of this vessel as a strong indication of evolving Chinese war fighting capabilities. The Chinese Navy (PLAN) is outpacing the rest of the world in naval innovation and ambition as well as just shipbuilding output.

Update

Photo shared online 23rd Sept 2026. Beware AI enhanced versions

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Hiding behind signs warning onlookers not to take photographs, a previously unreported stealth boat has been seen in at least two Chinese ports. The vessel has been in the water for some time but had evaded the attention of onlookers, until now.

It has a catamaran layout with a large hangar space taking up most of the upper structures. A generous cockpit over the bow suggests that it is ordinarily crewed, but like all new Chinese special purpose vessels these days there’s a possibility that it is ‘optionally crewed’. Although its overall lines appear stealthy, there is a large lattice mast above the bridge.

The design immediately brings to mind the American M80 Stiletto design, used as a Special Forces transport. It also bears some similarities to the French Espadon (Swordfish) MCM (mine countermeasures) vessel which is no longer active. That vessel is much more box-like, there is no chance of mistaking them, but the overall layout is similar with a catamaran hull and large hangar in the stern. The Espandon’s hangar can carry a towfish or other uncrwed payloads. In China, some Type-022 missile boats have been modified with large box-like superstructures resembling this, although I do not think that the two types are related.

Reference image of the American M80 Stiletto. US Navy photo.

The most straightforward explanation is that this design is some sort of drone mothership, similar to the Espadon. In this line of thought, possibly it is uncrewed. We may one day find out.

The sign reads ‘no photos’

Second Stealth Catamaran

Another design, but with an open working deck. This one may be for launching underwater drones, or for towing sonar towfish. Note that the three objects along the side are fenders.

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The Magura MV11 broke cover at Independence Day in Kyiv on 24th August when one took part in a parade on the river) That example was likely operated by Ukraine’s armed forces, likely the Navy (VMS-ZSU).

Larger than typical Ukrainian USVs which are 5-7 meters long, the MV11 is 12 meters (39 ft) long. And it weighs much more at over 10 tonnes, with a payload capacity in the region of 2 tonnes. That’s more than enough to carry a large battery of smaller aerial drones, either for attack or air defence. The fit shown, likely its primary one, is a bank of 18 Sting interceptor drones in individual box launchers. The interceptor drones take off vertically.

Ukraine has already been experimenting with launching interceptor drones from USVs to extend Ukraine’s anti-drone defences offshore. The increased carry capacity of the MV11 takes that to a more mature level. We can speculate that the MV11 platform could be used to mount other types of interceptor drones, or even larger missiles.

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Footage of the Ukrainian surface drone strike on Sochi, which struck the Russian Government linked special ship Nefrit, also shows a rare glimpse at something else. In the harbour the Russian navy has deployed trained dolphins and belugas to defend against divers. The pens are just visible, fleetingly, in video footage posted on Russian social media.

The attack involved British built Kraken USVs, the first time that they have been seen in public sources in the Black Sea.

A Kraken USV, seen here at the Combined Naval Event (CNE) in UK, 2026.

The harbour also has a floating boom defense fitted, but the Nefrit was tied up along the sea wall outside this defensive line.

Reference satellite image of the pens from Google Earth. The square pens are for dolphins, and the octagonal one for Beluga whales.

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Russian Navy Beluga whale

The Shadowfin drone is designed and built by Danish company Søens Tech, which has a background in innovative Mechatronics technologies to support underwater infrastructure projects, especially in Horizontal Directional Drilling (HDD). The Shadowfin is thus, while innovative and unconventional, developed by engineers intimately acquainted with watery arena.

Among Western designs Shadowfin stands out as being engineered for truly low-cost warfare. Its hull is a simple fiberglass tube, and the thrusters are commercial off the shelf units. While this will limited its operating depth, it results in a very affordable platform.

Shadowfin on display at DALO Industry Day 2026. Photo Naval News.

Specifications (estimates)
Length: 7 meters
Diameter: ~0.5 m
Displacement: 1.5 tons
Payload: ~300 kg

The thrusters are unusual. Shadowfin uses two rim-drive pumpjets where the blades rotate around the outside of the rim, leaving the center where the axel normally is completely clear. This arrangement is increasingly available in commercial thrusters, but has yet to be widely seen in defence projects.

The rim-drive pumpjets appear to be an underwater-optimised type built by Copenhagen Subsea. Rim drive designs use the rim itself as the motor, eliminating the need for the complexity and moving parts of the hub. Passing electricity through the rim spins the ring directly, removing the need for a gearbox, drive shaft, or seals. This means that it should, in general, be quieter too.

Shadowfin on display at DALO Industry Day 2026. Photo Naval News.

The design features a tall, fixed mast which can house cameras and other sensors, as well as navigation and communications antenna. It is also proposed that it could include a short mast to allow an internal combustion engine in the hull, which would significantly increase endurance.

Shadowfin is intended to carry a 300kg payload, about the same as a heavyweight torpedo, enabling both ISR (intelligence, surveillance and reconnaissance) missions and direct strike. Soens Tech propose an improved version, Shadowfin Enhanced, armed with a MU90 Impact lightweight torpedo. This weapon is not used by Denmark but has been sold to Ukraine for use aboard their future Ada Class corvettes. Soens intend it to provide an anti-submarine warfare capability. Being low cost, it can also be used as a decoy or forward sensor node. We can therefore envisage a formation of Shadowfins with some drawing the target in while those behind are positioned to launch the torpedoes in response.

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At least 21 special covered boast hangars have been dug into the southern shore of Lake Donuzlav in Crimea. These defended positions are likely for Russian surface drone (USV – uncrewed surface vessel) use. Information has now been made public from Ukrainian CyberBoroshno (КіберБорошно) OSINT sources.

Credit CyberBoroshno

This matches an observed increase in Russian Navy (and possibly other armed forces) use of USVs to attack the Odesa region. Some attacks have been launched from Chornomorskoe, further north on Crimea, but a base on Lake Donuzlav has long been suspected.

The base is dispersed in two areas. Construction of the first set of 8 hides, at Donuzlav Air Base in the vicinity of 45.3424°, 33.0532°, started in February 2026. The second set of 8, between Donuzlav Air Base and the historic naval base at Novoozernoe (confusingly called ‘Southern Naval Base’) in the vicinity of 45.3626°, 33.0608°, were started just after. Digging the inlets used mechanical diggers from the shore side. Both sets of hides were largely complete by the end of the second week of March, but the number have been increased over the months to 13 at the second site.

The design of both sets is similar. Around half of the hides appear covered at any point in time. Some USVs and related equipment may be stored in revetments at Donuzlav Air Base and the surrounding area.

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A surface drone (USV) has been found off the coast of Romania, drifting close to the Neptun Alpha drilling platform. As the vessel began to drift away it was hit by cannon fire from a Romanian Air Force F-16 fighter. It was subsequently destroyed by EOD (Explosive Ordnance Disposal) personnel. The black-painted craft appeared to be dead in the water, with seagulls gathering on its hull. It is reported to be of Russian origin.

Similar in size to other USVs operated by both sides in the Black Sea, this appears to be a previously unreported type. It is not closely related to the Russian Navy-linked model of USV observed during raids on Odesa.

There are no signs of impact fuses on the bow so it may not have been carrying an explosive ram-warhead. However there is a large hinged hangar in the forward hull so it may have been equipped with missiles or aerial drones of some sort.

Key: A) flat antenna, possibly satellite communications such as StarLink B) hangar C) commercial surface navigation radar D) flat antenna, possibly satellite communications such as StarLink E) fixed flat forward facing antenna, possibly air-search radar F) MESH radio antenna G) Electro-optical sensor.

Russian USVs have become more prevalent and more threatening in the Black Sea. However, their inability to use StarLink and Ukrainian countermeasures have at least blunted their potential in Russian hands. Ukrainian USVs however, remain a serious threat and shaping tool throughout the Black Sea despite high attrition, and have recently come into their own disabling sanctioned tankers.

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CLICK to Enlarge.

Russia’s new Pr. 09851 class submarine, Khabarovsk, has started sea trials after almost 9 months of fitting out and degaussing in Severodvinsk in the Russian Arctic. The unique submarine was launched at the Sevmash yard there in November last year.

The vessel is in many ways similar to the Pr.955A Borei-A Class, and highly-likely shares the same reactor and propulsion, but has the missile tubes swapped out for a Poseidon nuclear-armed nuclear-powered intercontinental torpedoes. The Poseidon are carried in the bow behind large outer shutters, like the similarly equipped Pr. 09852 submarine Belgorod.

CLICK to Enlarge. Updated profile based on latest analysis.

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The ship loaded its cargo at Portovaya near St. Petersburg (vicinity 60.5093°, 28.1779° - about as far from the Russian city and as close to the Finnish border as is possible for the dangerous product) and is being escorted out of the Baltic by the Russian Navy Pr. 22350 Gorshkov Class frigate Admiral Kasatonov.

Portovyy escorted by Admiral Kasatonov today. Photo via Frank Behling, BlueSky.

It is unlikely that the ship, laden with LNG, will actually sail to Murmansk as the final destination; Russia does not need to export LNG to itself. Instead, its cargo is likely for East Asia, presumably China. This would involve sailing across the Northern Sea Route (NSR). So the cargo either needs to be transhipped to another tanker for the journey, perhaps a better ice-hardened one, or Portovyy has to sail there herself. I would expect the latter, but if a transhipment is made it may be in a fjord just west of Murmansk.

Sending LNG tankers from the Baltic export terminals, around the top of Russia, to the Pacific would be a new tactic. LNG tankers do sail across the top of Russia, but from the gas terminals there, not from the Baltic. Only one LNG tanker has made the transit from the Baltic before, Velikiy Novgorod in 2023, and that appeared to be more of a test or demonstration. And none sailed this way in the past two years, although several crude oil tankers did. Instead, LNG cargos from the Baltic have been sailing south through the Mediterranean/Suez or around Africa.

The Russian shadow fleet LNG tanker Arctic Metagaz after being struck by surface drones (USVs) in the Mediterranean. The ship wasn’t fuelled by LNG, but the massive explosions, which blew out whole sections of the double hull.

Since 2022 Portovyy has been anchofred near Portovaya as floating storage unit (FSU) for LNG. But this doesn’t match with her current voyage which appears fully laden, so her role has logically changed to that of a regular vessel.

The NSR promises a shorter route during its summer ‘open’ season, and it avoids the war-torn Middle East. But these are unlikely to be the determining factor. It is more likely the success of Ukrainian surface drones (USVs) in blowing up LNG tankers outside the Black Sea (see Arctic Metagaz although Ukraine has not claimed credit). LNG cargoes are particularly vulnerable, and Russia is thus adapting to the Ukrainian threats to keep its important economic lifeline to fund its war in Ukraine open.

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Two very large and exposed LNG fuel tanks aboard the Chinese-built and operated Very Large Crude Carrier (VLCC) Yuan Rui Yang (IMO: 9843326)

Increasingly we are seeing new fuel types being used by merchant ships. This trend is driven by environmental regulations (regardless of their current status at the IMO - International Maritime Organization), which pushes ship operators toward equipping merchant ships to operate on alternative fuels. The fuels of interest ate liquefied natural gas (LNG), liquefied petroleum gas (LPG), liquid ammonia (NH₃), and methanal (MeOH).

Merchant ships are increasingly fired upon by several governments and groups in different areas around the world, including Russia, Ukraine, Iran, United States, the Houthi Movement in Yemen and pirate or terrorist groups. So far no ships with these fuels appear to have been in the crosshairs but it is at this rate only a matter of time.

LNG, LPG and Methanol fuels represent a extreme fire and explosion risk. Ammonia isn’t easily ignited but a leak of the toxic gas can be fatal, causing a mass-casualty event. In regular peacetime operations the risks of these fuels should be manageable (although the Min Jiang Kou incident naturally raises questions. The fuel tanks for the Min Jiang Kou were buried deep inside the hull but often the fuel tanks are in exposed positions on the deck, particularly on tankers.

The Russian shadow fleet LNG tanker Arctic Metagaz after being struck by surface drones (USVs) in the Mediterranean. The ship wasn’t fuelled by LNG, but the massive explosions, which blew out whole sections of the double hull, illustrate the explosive potential of the fuel.

Liquefied natural gas (LNG) is the leading, and most visible, alternative fuel type, particularly for crude oil tankers. Many newbuild vessels, such as car carriers and ferries, have the LNG tanks buried in the hull, but tankers, even new construction, tend to have them on deck in an exposed position.

French flagged Very Large Crude Carrier (VLCC) Eagle Valence (IMO: 9910234). No prizes for guessing where the two large LNG tanks are located.

LPG (liquified petroleum gas) and Ammonia can be clustered together because some ships can use either type of alternative fuel. But most seem intended to use one or the other as an alternative to traditional fuels. Obviously ships carrying these chemicals as cargo can ‘self-bunker’, but other ships need additional fuel tanks added, Like LNG, these tanks are often above deck in an exposed position. LPG is highly flammable and explosive, while ammonia is extremely toxic and, because it is slightly lighter than air and colorless, can create mass casualty events if it leaks.

French-flagged LPG Tanker Champagney (IMO: 9983499) with LPG tanks on deck. This ship is reportedly dual fuel.

Newly constructed Belgium flagged Bulk Carrier Mineral Latvija (IMO: 1029314) has ammonia tanks behind the superstructure. Some ships using LNG also have the tanks in this position, particularly if Bulk Carriers which need the deck space above the cargo hatches free from obstruction.

Chinese shipyards in particular are churning out LNG powered tankers.

Satellite image of 3 vessels under construction at Bolshoy Kamen in Russia, 2024. Based on visual clues, the upper two appear to be LNG (or possibly ammonia) fueled tankers, while the lower one may be LPG or ammonia fueled.

It is clear that strikes on merchant vessels is an increasingly significant factor in warfare, whether people like it or not. From a defence analysis perspective we therefore need to carefully consider how this trend in alternative fuels will affect the risks and opportunities in naval warfare going forward.

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