Special force small team attack craft either surface or subsurface have gained importance in light of their potential for littoral raids.
Special Forces (SF) operations at sea have been clouded in a shroud of secrecy compared to land-based SF deployments. But a renewed focus on maritime SF capabilities has been brought into sharp focus with the success of Ukrainian attacks on Russian forces in the Black Sea. The use of marine SF units and the ability to covertly insert operators in the littoral regions presents an important capability in the age of great power competition (GPC).
The SF community is adapting to the new strategic environment whereby GPC is more likely to bring about a conflict between peer or near-peer rivals. Defensive strategies centred on Anti-Access Area Denial (A2AD) systems implemented by great powers such as China and Russia will make it difficult for expeditionary forces employed by the United States, its NATO allies in Europe and its allies in the Indo-Pacific to deploy against them in-theatre without being detected and exposed to attack.
It means that the covert and clandestine nature of SF capabilities at sea and in the littoral and riverine environments will become increasingly important for forward surveillance, targeting and raiding. SF operate in small-unit teams and use a variety of methods and equipment to access denied areas. At sea this means using small surface vessels and underwater vehicles to both insert and extract these units and their equipment without being discovered.
In terms of surface vessels, SF teams use high-speed interceptor craft, rigid-hull inflatable boats (RHIBs) and inflatable boats often deployed from a larger mother ship from far offshore, or a submerged submarine closer in to enter enemy held coastal areas. These platforms are specialised for SF operations with the ability to host additional fire support weapons, sensors for intelligence gathering and communications systems for command and control, as well as any other specific mission requirements.
Underwater SF teams use a variety of ‘wet’ swimmer delivery vehicles and undersea vehicles that can be used by combat divers using underwater breathing equipment and also dry submersibles that keep both personnel and their equipment dry.
For example, U.S. Special Operations Command (USSOCOM) Naval Special Warfare (NSW) units possesses the largest and most sophisticated fleet of surface and underwater platforms for SF operations.
NSW teams operate a surface fleet that consists of Combatant Craft Heavy (CCH), Combatant Craft Medium (CCM), Combatant Craft Assault (CCA), and Special Operations Craft – Riverine (SOC-R). Meanwhile its fleet of undersea platforms consists of the SEAL Delivery Vehicles (SDV), Dry Deck Shelter (DDS), and Dry Combat Submersible (DCS).
USSOCOM PEO Maritime (PEO-M) is currently looking for a new CCM Mk2 to replace the existing 31 CCM Mk1 platforms that were delivered by Vigor Works. Funding for a new acquisition has been provided from FY2025-28. The Mk2 will require a host of new capabilities to allow NSW teams to operate more effectively in a contested environment and remain undetected. Emerging requirements include the need for advanced data transfer in a GPS and denied electro-magnetic environment, additional precision navigation and timing (PNT) capabilities, and higher levels of platform readiness.
The CCM Mk1 stealthy special operations boats were introduced in 2015 as a replacement for the SOC MkV and Naval Special Warfare Rigid Inflatable Boat (NSW-RIB). Displacing about 29.8 tonnes the CCM Mk1 are over 60 feet (18.47 metres) long with a beam of 13ft (4m) and have space for 19 passengers with a crew of four. The cruising speed is 40kt (74km/h) offering a range of 600nm and a can attain a top speed of 52kts (96km/h). Norway has ordered two CCM Mk1 units in a contract awarded on 10 May 2023 for $22 million. Deliveries are expected by August 2025.
USSOCOM also operates 32 CCAs, which were delivered from US Marine Inc by August 2021 and three CCH platforms. The CCAs are smaller versions of the CCMs that are 41ft (12.5m) long and are transportable in a Lockheed Martin C-130 and Boeing C-17 aircraft for airdrop delivery, which means they can be rapidly deployed anywhere at sea worldwide. The CCAs employ a deep-V shaped monohull and can reach a top speed in excess of 40kts (74km/h) and has a radar mast that hosts a search radar and FLIR camera system.
Meanwhile the CCH SEALION (Sea Air Land Insertion Observation and Neutralisation) craft at 32tt and 77ft (23.5m) long are larger than the CCM and CCA and can transport platoon-sized units of about 30 personnel. The first pair of CCH were delivered by Vigor Works in 2003 with a third delivered in 2021. These are being used in ways that were different than originally intended. In May 2024, PEO-M announced that it had ordered a fourth unit from Fincantieri in April and there are plans for a fifth unit. These two new CCHs will replace the two earlier platforms when they retire.
USSOCOM’s primary riverine and littoral vessels is the Special Operations Craft – Riverine. At 33ft (10m) long with a beam of 2.97m and displacing 9.4 tonnes the SOC-R have a crew of four and can transport eight USN SEALs. US SOCOM has 24 SOC-R in its inventory and they are transportable as an underslung load from a CH-47 helicopter or inside a C-130 tactical transport aircraft.
The U.K. Special Boat Service (SBS) operates the Fast Interceptor Craft that reportedly has a top speed of 60kts (111km/h). Built by BAE Systems Maritime there are three variants available: the FIC 33, FIC 40 and FIC 180. These are 34.5ft (10.75m), 42.5ft (13m) and 59ft (18) long respectively and are transportable in C-130, C-17 and A400M aircraft.
In Europe, the Netherlands Maritime special forces are replacing the Fast Raiding Interception and Special Forces Craft (FRISC) from 2024. The Royal Netherlands Navy operates a fleet of 48 FRISC, but at just 39ft (12m) long and 7.4 tonnes displacement with space for just six operators they have limited capacity. It is expected that the procurement of 12 Littoral Assault Craft (LAC) and eight Littoral Craft Mobility (LCM) that will replace the RNLN’s existing 12 landing craft vehicle personnel (LCVP) will also replace the FRISC capability. The LAC will enter service from 2026 with the LCM from 2028.
The problem with surface vessels is that they can be detected by the maritime surveillance systems of rival countries. With the proliferation of surveillance platforms – especially uncrewed systems – sensor systems and rapid data transfer it means that even small fast-moving craft can potentially be discovered and destroyed.
Underwater Attack
The underwater environment is far more effective for the deployment of SF from the sea. Radar and electro optical / infrared (EO/IR) systems cannot be used and detection systems are limited to sonar systems. By remaining stealthy this offers SF higher levels of survivability and success when deployed.
Underwater SF personnel have usually deployed from submarines or surface ships using swimmer delivery vehicles (SDVs) such as the U.S. Navy’s SEAL Delivery Vehicle, which has been in-service since the early 1980s. The latest variant in use by USSOCOM is the SDV Mk8.
SDVs are flooded so operators have to use wet suits and breath using air supplies from the vehicle or from their own scuba equipment. It means that operators are exposed to cold temperatures, which limits range and endurance. The SDV Mk8 is also used by the U.K. Special Boat Service (SBS) and other SDV variants are widely used by SOF units worldwide to provide a sub-surface SF insertion and recovery capability.
For long distance operations, SDVs are transported into theatre on submarines, usually nuclear-powered attack submarines (SSNs) using a Dry Deck Shelter (DDS) fitted to the submarine’s hull. DDS are modules that can be fitted to a SSN that allows them to deploy and recover SOF teams and their SDVs while submerged. The U.S. Navy has five DDS used on its Ohio-class submarines, the oldest of which has been in operation for almost 50 years.
The U.K. Royal Navy’s Astute-class SSNs were designed to be able to host DDS modules, which were built under Project Chalfont and known as a Special Forces Payload Bay. China’s Sea Dragon SF units have been seen operating SDVs from their Shang-class SSNs using a dry deck shelter. French SOF command uses the PSM3G Propulsor Sous-Marins 3rd Generation) Special Warfare Underwater Vehicle (SWUV), 10 of which have been delivered by ECA. The 28ft (8.5m) long SWUV is interoperable with the Dry Deck Shelter fitted on the French Navy’s new Suffren-class SSNs.
In the U.S., the SDVs are gradually being replaced by the SDV Mk11 Shallow Water Combat Submersible (SWCS), which displaces about 4.5tonnes and is 22ft (6.8m) long and 4.9ft (1.5m) wide. It has two crew and can transport four passengers with the ability to operate at depths of up to 328ft (100m) with a range of 50nm (92.6km) and has a top speed of 9kts (16.6km/h). Teledyne is delivering up to 10 SWCS to the USN SEALs and U.K. SBS, who have ordered three.
A new DDS programme for the U.S. Navy – dubbed DDS Next – which started in FY2024 is in the research and development phase. DDS Next will develop a new DDS that can fit on the USN’s Virginia-class submarines. The intention is for the new shelter to accommodate 18 swimmers and their equipment – including the SDV Mk11 – and potentially connect to the new Dry Combat Submersibles (DCS).
Using DCS is considered more effective for transporting SF units longer distances and providing protection from the elements. It means that operators can retain their strength and concentration for operations on location rather than expending their energy on transiting to the deployment area.
In June 2023, a new DCS for USSOCOM achieved an initial operating capability (IOC). Built by Lockheed Martin the DCS can transport SF operators under the surface without the need for a wetsuit or individual breathing apparatus. Personnel can enter and leave the DCS whilst submerged using a lock-in/lock-out system. The DCS is operated by two crew and can insert eight U.S. Navy SEALs out to a range of 62 miles (100km) underwater at depths of up to 100ft (30m).
The advantage of dry submersibles is that SF personnel can be transported to their destination dry without wasting their own energy swimming or using up oxygen bottles on long transits offering the possibility of longer duration missions at longer ranges.
The DCS is based on a design from MSubs. At the Indo-Pacific Maritime exhibition in 2022, MSubs displayed a new variant of its DCS range of underwater vehicle designs – the S302 Diver Lockout Submersible. The S302 is 31ft (9.5m) long, 6.5ft (2m) wide and displaces 13.6t. It is designed to operate with a crew of two and can transport six passengers across two compartments at speeds of up to 10kts (18.5km/h) out to ranges of about 60nm (111km) at up to 300ft (92m deep). Its life support system can last for 24 hours with the ability to extend to 96 hours and there is a swimmer lockout hatch in each compartment. MSubs is building the S302 at its facility in Plymouth, U.K.
The S302 offers a range of improvements over the earlier S301 model, three of which were delivered to USSOCOM at Joint Expeditionary Base, Little Creek-Fort Story in Virginia from 2015-2022. The S301 is a larger design at 40ft (12m) long, 7.2ft (2.2m) wide and displacing 30t. It has space for two operators plus eight passengers but with a range of 25nm (46.3km) at depths of more than 36m.
However, because of its size DCS have to be transported into theatre using large logistics ships and deployed using cranes or towing rigs. This limits the deployment options compared to SDVs which are transportable on submarines. To fill this capability gap USSOCOM NSW is also considering a new Submarine-Launched Dry Submersible (SLDS).
In July 2023, the new Victa Diver Delivery Unit (DDU) from manufacturer SubSea Craft achieved a proof-of-concept certification in the U.K. reaching technology readiness level six. Victa has been designed as a long-range insertion craft that can travel up to 240nm (444km)on the surface at a speed of 40kts (74km/h) with the ability to submerge within two minutes and get depths of up to 100ft (30m). When submerged the DDU has a range of up to 25nm (46km)operating at a cruising speed of 6kts (11km/h) with the capability to surge to 8kts (14.8km/h) with four hours of air. The DDU is 45f (11.95m) long and 7.5ft (2.3m) wide displacing about 20.500lbs (9,300kg) with the capacity to hold a crew of two and six divers.
Built to a monohull design from carbon fibre and a Diab core, the DDU design incorporates the features of a fast interceptor craft and a SDV so that it can achieve the surface and subsurface capabilities of both. It means the Victa can approach a target rapidly on the surface before submerging and completing the final part of its journey covertly. SubSea Craft is developing the prototype further and making additional enhancements as well as beginning the construction of a second craft.
Elsewhere, semi-submersible delivery vehicles are also under consideration. At the SOF Week exhibition in 2023, UK-based JFD announced it was handing over its first production model of the Shadow Seal tactical diving vehicle (TDV) to its U.S. partner Blue Tide Marine, which will demonstrate its capabilities to U.S. customers. The Shadow Seal TDV is 26ft (8m) long, 6.2ft (1.92m) wide with a displacement of 5,500lbs (2,500kg). It can operate as a surface craft with speeds of up to 7kts (13km/h) with a range of 60nm (111km), as a semi-submersible or fully submerged platform for transit at 13ft (4m) deep at speeds of up to 5kts (9.2km/h) giving a range of up to 40nm (74km), or it can remain stationary at nearly 100ft (30m). It can transport four combat divers in two compartments with two seats each.
The need for stealth remains paramount and SF maritime delivery vehicles will have to ensure that they retain the balance between speed of entry with remaining undetected. As A2AD defences become more sophisticated and uncrewed systems with more accurate sensors make the littoral battlefield more transparent restricting the movement of conventional forces, so the importance of SF capabilities in providing surveillance about defensive sites and also degrading those defences themselves becomes ever more important.
by Andrew White
