HII’s newest Remus 300 AUV has a depth rating of 305m. This year, it won a major contract for the USN’s SUUV Lionfish programme. (Image: HII)

MUUVing with the times: Seafloor threats drive UUV development

As concerns over seafloors becoming a new arena of warfare grow, navies are increasingly seeking systems capable of autonomous underwater operations. Companies are consequently stepping up to meet surging demand.

Gordon Arthur

Gordon Arthur

Hydrographic surveys, MCM, rapid environmental assessment, ISR, inspection of critical national infrastructure, intelligence preparation of operational environments (IPOE) and salvage are all standard fare for today’s UUVs.

One day, strike-capable UUVs may become commonplace, but there is already growing concern that seafloors may become a new arena of warfare. Home to vulnerable infrastructure such as power cables, pipelines, fibre-optic cables, windfarms, oil/gas extraction and military surveillance networks like America’s Integrated Undersea Surveillance System, seabed infrastructure needs protection from kinetic or non-kinetic attacks or intrusions.

This topic came into sharper focus when a Norwegian undersea surveillance network capable of detecting submarines had 4km of cables mysteriously removed last year. The chief suspect is Russia, which owns an ‘oceanic research’ ship called Yantar that carries submersibles capable of cutting undersea cables.

Incidentally, France unveiled its Seabed Warfare Strategy in February, laying out three strategic goals: guaranteed freedom of action for French armed forces in maritime environments; protection of underwater installations; and ensuring interests in exploration and exploitation of mineral/energy resources in national jurisdictions. France’s goal is to patrol the seabed down to 6,000m, covering 97% of the world’s seafloor.

In an interview with Shephard, Chris Lade, defence sales manager for Saab’s Underwater Systems, said interest in seabed warfare is rising. Although designed for commercial operations, Saab’s Sabertooth ‘is ideally positioned to be in place in a field that needed monitoring’ in an underwater-residency scenario. The 3.8m-long Sabertooth can be charged via induction in a seafloor docking station, providing surveillance of infrastructure up to 3,000m deep for six months at a time. The hover-capable Sabertooth, available in single-hull and double-hull configurations, is available as an AUV or ROV.

🜂 The Sabertooth AUV from Saab is designed primarily for commercial applications such as inspection, maintenance and repair, as pictured here, but it could also be ideal for seabed residency. (Image: Saab)

As the world’s largest maker of electrical ROVs, Saab has updated its tried-and-tested Double Eagle (recently sold to Poland) and introduced the new cuboid-shaped eWROV. Saab has just sold ten eWROVs to Ocean Infinity, which happens to hold a major US DoD contract.

Additionally, Saab makes the torpedo-shaped AUV62 available in acoustic target and mine reconnaissance variants. The AUV62-MR’s sonar will be upgraded over the coming year, whereas Lade said the AUV62-AT training aid is garnering attention as navies prioritise ASW. Saab delivered an AUV62-AT to the UK in 2019.

USN programmes

Examining current USN programmes of record will help indicate what capabilities the world’s most powerful navy is seeking. Starting with the largest category, the Extra-Large UUV (XLUUV) is represented by Boeing’s 15.5m-long diesel-electric Orca. In March 2017, the USN awarded Boeing a $274 million contract, with the Orca building upon Boeing’s experience with its Echo Voyager commercial prototype. Five Orcas are under construction, but the first delivery has been delayed till September.

Pier-launched Orcas could carry modular payloads such as mines for seabed warfare and perform ISR, ASuW, ASW, EW, MCM and strike missions.

🜂 No photos are available showing the full hull of Boeing’s Orca XLUUV, so this one of an Orca sailing just beneath the surface will have to suffice! Boeing won a USN contract to build five such submersibles. (Photo: Boeing)

Asked about XLUUVs, Boeing told Shephard: ‘Given the dynamic global security environment and continuing budget pressures faced by governments around the world, Boeing sees an opportunity for XLUUVs to play a significant role complementing existing/future fleet structures by providing flexible mass and multirole capabilities powered by advanced autonomy.’

Shephard asked Boeing about the challenges that XLUUVs entail. ‘Designing them with advanced autonomy and sufficient redundancy for long-term reliable operation without hands-on human intervention is key to XLUUVs. In addition, having sufficient energy storage and/or onboard power generation capability to enable those operations is required.’

Moving down the scale, the USN’s next programme is the Large Displacement Unmanned Undersea Vehicle (LDUUV), known as the Snakehead. Designed to fit inside a submarine’s dry deck shelter, the Snakehead can scout ahead, hunt for enemy ships and submarines, and conduct EW missions. The LDUUV would be the submariner’s equivalent of a loyal wingman, reducing risk for crewed submarines.

The secretive Snakehead programme was initiated in 2012, and a government-led prototype using lithium-ion fault-tolerant batteries was christened in February. However, the navy’s FY2023 budget suddenly terminated the Snakehead programme. After spending $200 million up till 2021, the USN admitted that ‘cost and schedule delays’ had occurred integrating Snakehead with Virginia-class submarines.

The USN’s medium-category MUUV contains parallel types that can be surface- or submarine-launched: the Knifefish and Razorback. Production of ten Knifefish Block 0 UUVs, based on the Bluefin-21, started in 2020.

Paul Dalton, VP of undersea systems at General Dynamics Mission Systems, told Shephard: ‘We delivered our first Knifefish system to the USN last year under a programme of record. Knifefish is a mine countermeasure UUV deployed from Littoral Combat Ships and other vessels of opportunity. Knifefish detects, classifies and identifies volume, proud and buried mines in high-clutter underwater environments. Low-rate initial production continues to move ahead at pace.’

🜂 The Knifefish for the USN is based on the 750kg Bluefin-21. It is a key part of the MCM mission package for USN Littoral Combat Ships. (Photo: General Dynamics Mission Systems)

As for the Razorback, which is based on the Remus 600, it is designed for battlespace awareness, mine warfare and IPOE. The first nine Razorbacks produced from 2020 deploy from submarine dry deck shelters, but an improved type – for which an RfP was issued in 2020 – will do so from submarine torpedo tubes. The latter, supposed to be mission-ready in 2024, will no longer require divers to launch/recover the Razorback from submarines.

This newer variant, which Shephard understands will be called Viperfish, represents a common MUUV that can support both the submariner and EOD communities. The latter currently relies on Swordfish and Kingfish UUVs, but a common Viperfish MUUV body with different sensor packages should be able to please both user groups.

The USN’s final category is Small UUVs (SUUV) that are portable and can be launched on the surface or from submarines. After a two-year prototyping effort involving multiple user evaluations and spiral developments, Huntington Ingalls Industries (HII) announced on 30 March that its Remus 300 had received a contract under the Lionfish SUUV programme.

The Remus 300 defeated the Iver4 from L3Harris. The initial phase will see production and testing of Remus 300s over the ensuing year. In 2024, rapid fielding should occur.

American activity

Apart from its Lionfish success, HII announced in June 2021 its first export of the Remus 300 – four units sold to New Zealand for MCM and surveying tasks.

Standard Remus vehicles are the 100, 300, 600 and 6000, the numbers referring to their metre depth rating. More than 600 Remus and Seaglider UUVs have been sold to 30 countries. The Seaglider uses changes in buoyancy to move through the water in a saw-tooth pattern; because it has no external moving parts, it can stay at sea for nine months.

Duane Fotheringham, president of the Unmanned Systems business group at HII’s Mission Technologies division, said the newest Remus 300 ‘is the culmination of design efforts resulting from customer feedback over the past 20 years’. It features swappable battery packs for 10h, 20h or 30h of endurance, open architecture allowing third-party integration of payloads and algorithms, and swappable advanced payload options.

Fotheringham added that, in the future, ‘capability-wise, we’ll continue to see advancements for payloads and sensors in the areas of SWaP. Customer requirements are driving payloads to be smaller, weigh less and consume less power so the UUVs can carry more sensors and go out for longer periods of time. We’ll also continue to see higher-density energy options with continuing improvements in battery technology, as well as maturing technology energy options such as fuel cells.’

HII predicted: ‘One of the biggest growth areas for capability will be in advanced autonomy capabilities. Improvements in computing power, and the application of AI/machine learning algorithms, are allowing us to rapidly advance the capabilities of our autonomy with advanced algorithms such as collaborative autonomy, health monitoring sensor fusion and perception.’

HII has developed its Odyssey advanced autonomy solution that enables collaboration across open-architecture platforms and across domains. ‘Our plan is to integrate pieces of Odyssey with Remus to increase the capabilities of the platform.’

Dalton provided Shephard with an update on General Dynamics Mission Systems’ activities too. ‘Much of our work in the last two years has focused on enhancements to our existing UUV offerings. For example, we’ve improved the depth rating on our Bluefin-12 from 200m to 300m to further expand its operational capability. Energy has been another focal point for the team. We’re coming through a complete revamping of our battery line-up that will increase endurance and reduce life-cycle costs across our products. We’ve also done several excursions with new sensors and payloads that will inform future offerings,’ he said.

The company’s largest offering is the Bluefin-21, but the Royal Australian Navy uses the smaller 70kg Bluefin-9 and 250kg Bluefin-12 for MCM tasks.

Elsewhere, Teledyne Technologies makes the buoyancy-driven Littoral Battlespace Sensing-Glider (LBS-G) for the USN. The first LBS-G contract in 2009 was for 203 gliders, and the most recent five-year contract worth $27.4 million was announced in July 2021.

European efforts

The UK is also evaluating XLUUVs, with the RN receiving a 9m-long Manta from Plymouth-based MSubs in 2020. This $3 million project completed its first two phases in April; a third phase will see closer integration in operational environments. The Manta demonstrator could eventually lead to an operational British XLUUV, a capability that would prove useful since the RN fleet will never exceed seven submarines.

In mid-April, the UK announced a £32 million ($40.2 million) contract to Atlas Elektronik for three Medium Autonomous Underwater Vessel (MAUV) systems (three AUVs each) for the RN. The first MAUV for this British Block 1 mine-hunting capability will be delivered in Q2 of 2023. These MAUVs comprise Atlas Elektronik’s SeaCat SAS with synthetic aperture sonar and an endurance exceeding 30h.

Apart from the SeaCat SAS, Atlas Elektronik’s most important AUV family has other versions too. The standard configuration features an Edgetech 2205 side-scan sonar for 8h missions. The extended-range type possesses extra batteries for 16h of endurance. The SeaCat’s SwapHead foremost-hull section permits sensors such as the SurveyHead and InspectionHead to be exchanged in less than 5min.

🜂 German company Atlas Elektronik recently won a significant contract for nine SeaCat SAS AUVs fitted with a synthetic aperture sonar for the Royal Navy. (Photo: Atlas Elektronik)

An Atlas Elektronik spokesperson told Shephard that the company is working on introducing SeaCat to other navies. Mine-hunting and naval hydrography are routine SeaCat tasks, but the German OEM is broadening its appeal with new applications like a SwapHead releaser mechanism that can attach charges to hard surfaces by means of a nail gun or by dropping objects. This capability has been initially tested.

Another SeaCat type is a submarine capability extender with high manoeuvrability and precise navigation for operations from submarines. ‘This application is under steady discussion and interest seems to grow,’ the spokesperson noted. Another interesting concept is using a SwapHead with depressor wings that turns the SeaCat into a towfish, thus eliminating the need for a winch.

An ASW application is coming into focus too. In cooperation with IAI Elta, Atlas is exploring bi-static sensing of targets using active sound sources on surface vessels. This operation requires larger AUVs capable of towing low-frequency towed arrays.

Atlas Elektronik shared: ‘Now, customers ask for more precision (more accurate navigation, images of higher resolution) but also new applications. This trend seems to lead to bigger systems, which are capable of incorporating or even towing larger acoustic arrays. At the same time, endurance will increase. With higher autonomy, new options to transfer data and commands are sought. Over-the-horizon satellite-based communication will be a backbone to satisfy the demand of bandwidth and range… In this context, we will witness a class of vehicles which include flying drones for this, but also for extended surveillance tasks.’

The German company also referred to a trend of extending the range of UUVs thanks to automatic delivery via USVs. ‘In future, there will be covert missions by operating submarines and, later, bigger XLUUVs with smaller, more agile AUVs for local activities.’

France, meanwhile, boasts UUV manufacturers such as ECA Group, its products ranging from the hand-launched A9 to the medium-sized A18 and the A27 with 50h endurance. Then, in April, RTsys of France announced Slovenia had ordered three of its products, namely the man-portable Comet-300 AUV, lightweight NemoSens AUV and diver-held Sonadive sonar and navigation system.

Elsewhere, Kongsberg Maritime produces the Hugin AUV family, which has been sold to 12 navies so far. The Norwegian firm recently introduced the 4m-long Hugin Edge, a smaller vehicle aimed at the littoral or low logistics segment. Weighing 300kg, the Hugin Edge is rated to 1,000m.

Richard Mills, Kongsberg Maritime’s VP of marine robotics sales, told Shephard: ‘In a system of this size, we wanted to pack in as much capability as possible, and also improve efficiency.’ This is achieved via a low-drag hull form that improves propulsion efficiency, and better packaging of the sensor payload.

🜂 This is a Hugin AUV from the Norwegian concern Kongsberg Maritime. The newest member to join the family is the smaller Hugin Edge that measures 4m long. (Photo: Kongsberg Maritime)

The Hugin Edge also focuses on operational efficiency through a new goal-based mission planning capability coupled with performance-based in-mission autonomy. Mills explained: ‘The planning tool enables operators to simply select an area and a function, set some performance criteria, and the system does the rest. It works out the most efficient and effective way of completing the task.’ Mills believes this capability is unique today.

He elaborated on new trends too, saying: ‘We’re starting to see the adoption of true autonomy and advanced autonomy, and data processing tools that will accelerate the adoption of uncrewed and autonomous systems. Combined with better over-the-horizon communications systems, uncrewed platforms allow safe operation whilst maintaining a low-latency view of the battlefield.’

An example is an MCM capability Kongsberg is working towards, comprising USVs and AUVs empowered with advanced decision-making capabilities for BLoS operations. ‘The goal is to launch a package of USVs, each with different capabilities. One may be dedicated to detection and identification, another to neutralisation and possible others to influence-sweep activities.’

Meanwhile, more capabilities are coming on platforms like the Hugin Endurance, which can perform persistent ASW and long-range route clearance missions lasting several weeks. Kongsberg is also a partner of Trondheim-based Eelume, which developed an articulated robot for subsea residence and inspection. Swimming like a snake, this Eely500 robot can access relatively confined spaces.

Asian interest

China’s PLAN displayed two HSU001 LDUUVs in a 2019 parade in Beijing. While there are no indications of how the PLAN plans to use them, the HSU001 features a nose-mounted sonar and mast-mounted sensor, which could allow them to be employed for seabed warfare alongside Chinese SSNs.

🜂 The PLAN exhibited two HSU001 large AUVs in a military parade in Beijing on 1 October 2019. Unsurprisingly for China, little is known about their roles. (Photo: author)

In December 2020, Indonesian fishermen discovered a Chinese-built Haiyi sea glider (possessing a 1,500km range and 60-day endurance) on the fringes of the Makassar and Lombok Straits. As part of an emerging pattern, Indonesian fishermen found another Haiyi in the Riau Islands in 2019. Their discovery demonstrates that China is busy collecting data for Chinese submariners. To enter the Indian Ocean, for example, Chinese warships and submarines must pass through chokepoints, the Makassar, Lombok and Malacca Straits being among them.

In March, Mazagon Dock Limited (MDL) in India issued a 15-page expression of interest seeking an overseas collaborative partner to help design, develop and construct a long-endurance XLUUV capable of ASW, ASuW, EW, MCM and strike missions. MDL listed key attributes of extended range, autonomy and persistence. ‘The XLUUV will transit to an area of operation; loiter with the ability to periodically establish communications, deploy payloads, carry out various pre-programmed missions and transit home.’

Supply and demand

Dalton assessed: ‘UUVs continue to be an area of immense technical progress. Sensor providers continue to introduce new components that drive major performance improvements in areas like precision navigation and data quality, or deliver comparable performance in a smaller, lower-power package, enabling their use on smaller platforms. Onboard data processing and automated target recognition are also seeing significant performance improvements year over year, reducing the timeline to connect the user with their data, and ultimately speeding up the decision-making process in tactical settings.’

Deploying weapons on AUVs is controversial, so policy questions have to be resolved first. However, Atlas Elektronik predicted: ‘It is merely a matter of time until AUVs are equipped with underwater weapons like torpedoes, mines, rockets or other charges. With increasing capabilities of AI, automatic clearance of sea mines may be one option, especially within the “system of systems” approach. Increased trust of users and technology development will bring uncrewed underwater systems towards the full spectrum of undersea warfare in coming decades.’

Conflict in Iraq and Afghanistan helped catapult UAVs into the forefront of military consciousness. This has not yet happened with UUVs, though increasingly nefarious underwater activities, or an ‘undersea conflict’, could well lead to greater UUV demand.

Follow the author @combatpaparazzi.