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By sea & stealth: maritime special forces tend to arrive in hostile territory by sea and by stealth, but where once they would be delivered by rubber dinghies from a submarine now they are using Special Delivery Vehicles (SDV) and even midget submarines.

Maritime special forces have a variety of roles that include covert reconnaissance and surveillance, hydrographical reconnaissance, minefield surveillance and covert ship/harbour attack. These require quiet vehicles with low acoustic or magnetic signatures to reduce the chances of detection and, for these reasons, many are made of nonferrous metals with battery-powered electric propulsion.

At the bottom end of the market are vehicles designed for one or two operators who are usually immersed in the water. Anteon has produced the Sea Shadow, which is actually a 107-kg diver propulsion vehicle for one or two people and powered by lead-acid batteries; despite this simplicity the vehicle is surprisingly sophisticated. The hull is of moulded high-density polyethylene plastic to provide a low magnetic signature while folding bow planes and rotating motors allow the vehicle to be deployed through a 76-cm escape hatch.

The Sea Shadow features electronic speed control with a manual back-up mode and an option of electronic drift compensation. A liquid crystal display provides speed, depth, battery duration and voltage details while there are visual warning signals on low battery power as well as unsafe rates of both ascent and descent. However, the vehicle has a range of only five nautical miles (9.25 km) at 2 to 3 knots and at a maximum of depth of 30 metres but it has still been acquired by a number of special forces including those of the United States.

A more sophisticated one-man vehicle is the Serbian Brodosplit R-l, which weighs 150 kg and resembles a torpedo, with the operator straddling the aluminium alloy hull behind the first of two buoyancy tanks. The vehicle has silver-zinc batteries operating a one-kW motor that provides a range of eight nautical miles (15 kilometres) at 2.5 knots (maximum speed three knots) at a maximum depth of 60 metres. The 52-cm vehicle can actually be housed in a submarine torpedo tube and the operator can deliver 40 kg of limpet mines of either the 7 or 15 kg size. Both Serbia and Croatia are known to have these underwater vehicles and the foreign customer list is believed to include Sweden.

Two-man units are more common and one of the most basic is the Cosmos Chariot CE2F/X100-T which is a development of the Italian so-called piloted maiali (pigs) used by the famous 10. Mas whose most famous exploit was to damage two British battleships in Alexandria harbour. The light (2.10-tonne) vehicle resembles a torpedo but with two open compartments amidships for the crew, it also has ballast tanks that can be blown or flooded to ascend or descend and a small rudder to turn.

It reaches the operating area either attached to or towed by another vessel and can operate down to 100 metres. The electric motors give it a submerged range of 50 nautical miles (95 km) at four knots, the maximum speed being five knots. The payload can be a 230-kg charge or 150 kg of limpet mines. These vehicles are known to have been acquired by Argentina, India and Pakistan. The latest version includes a digital control module, displaying navigation and platform details, as well as a fully integrated autopilot.

The Croatian Brodosplit R-2 follows a similar concept but the two-man crew ride astride the 1.41-tonne spindle-shaped vehicle. The 3.3 kW DC electric motor is powered by either lead/acid or silver-zinc batteries. Navigation equipment comprises an aircraft-type gyro compass, a magnetic compass, depth gauge with a 0 to 100-metre scale, echo-sounder, sonar, two searchlights and so on. All navigation equipment is housed in a waterproof container.

With the lead-acid batteries it can travel 23 nautical miles at 3.7 knots and with the silver-zinc batteries 46 nautical miles at the same speed, the maximum speed being 4.4 knots. The R-2 can operate down to 60 metres with a maximum limpet mine load of 250 kg.

An interesting modern two-man vehicle is the Columbia Research Corporation Piranha, which uses a powerful brushless DC motor and silver-zinc batteries. The 1.63-tonne glass-fibre vehicle has a range of 27.5 nautical miles at five knots but is capable of burst speeds of seven knots and can operate down to 70 metres, although it will usually be kept at 45 metres. A high-resolution multi-beam sonar is fitted for obstacle avoidance. Although the vessel is 'wet', forcing the crew to wear scuba gear, even though they are fully enclosed.

There is a growing demand for larger SDVs to deliver teams of special forces or other groups with a large amount of equipment who can then conduct wider or more effective operations. These vessels are often mini submarines but differ from submarines in that they lack a pressure hull and the crew compartment is generally flooded, forcing the personnel to wear underwater breathing apparatuses.

One of the first, developed by the US Naval Surface Warfare Center, was the Mark VIII. The original Mod 0 version was something like the Pompidou Centre or Lloyd's building consisting of a pipe-work frame which also served as part of the ballast system. In 1995 the Mod 1 version replaced this structure; it featured flat aluminium framing which is lighter, stronger and easier to maintain. Mod 1 included larger internal space by the repackaging of internal components such as air flasks. Also the movable-weight ballast system was replaced by trim tanks.

The Mod 1 has also received a substantial improvement in its electronics, with the navigation and sonar systems now housed in watertight containers. The vehicles received a precise Doppler sonar and integrated GPS receiver, secure communications as well as new digital displays.

The vehicle, used by American and British special forces, still carries six personnel (including the pilot) but now has rechargeable silver-zinc batteries and a quieter new motor with increased power doubling speed to nine knots and the range to 36 nautical miles (66 km), although the Mk VIII can travel at a depth of only six metres.

The short range of these vehicles means they must be delivered by submarine. Since 1982 the US Navy's traditional submarine manufacturers, General Dynamics' Electric Boat and Northrop Grumman Newport News, have built air transportable Dry Deck Shelters (DDS) to house these vehicles and their support personnel on the backs of nuclear submarines with the installation usually behind the sail. The shelters transport and launch an SDV or are used by combat swimmers.

The 30 tonne DDS is subdivided into three watertight compartments each capable of independent pressurisation to at least 40 metres--allowing its use even when the submarine is submerged. The forward compartment is a hyperbaric chamber to treat injured divers. The middle compartment is a transfer chamber providing access to the other compartments and the submarine while the aft compartment is a floodable hangar for a single SDV or other vehicles as well as the special forces' equipment and houses up to 20 personnel. About half-a-dozen American and British submarines are equipped to operate the DDS and the Indian Navy has expressed interest in acquiring them following the United States-India rapprochement of recent years.

The Mk VIII has been augmented by the Columbia Research Corporation Dolphin or SDV-X in both US and British service. This is essentially a larger version of the Piranha carrying up to eight personnel but with brushless DC motor and silver-zinc batteries. These will provide a range of 56.5 nautical miles (104.5 km) at 5 knots as deep as 91 metres, but burst speeds of nine knots are possible.

The sophistication of these 2.75-tonne vehicles is illustrated by the electronics fit. This includes colour liquid crystal displays and colour digital charts, while the computer-based navigation system includes GPS and Doppler velocity log. There is also a multi-beam obstacle-avoidance sonar to distinguish targets while the integrated communications suite includes an underwater telephone and a VHF radio.

Traditionally SDVs have been produced by the United States, Italy and Serbia, but a new player is the United Arab Emirates. Emirates Marine Technologies (EMT) has developed four SDVs since the mid 1990s, both for domestic use and for neighbouring countries. The Classes 4, 5, 6 and 8 are built of glass reinforced plastic and carbon composite materials, with the first two being two-man units powered by an eight-kW motor with external battery packs, the three-tonne Class 4 uses silver-zinc while the eight-tonne Class 5 uses nickel-cadmium. Their sensor/control suites include a sonar, echo sounder, GPS, electronic compass and electronic mapping facility and an onboard computer. They have a range of 60 nautical miles (110 km) at six (maximum speed 7) knots and can operate down to 50 metres, the Class 4 carries a 200 kg payload while the Class 5 can handle 450 kg.

The manufacturers are now developing two more ambitious designs, the Class 6 and Class 8, to carry four and eight (two crew) personnel. The former will have two eight kW electric motors for underwater use and a diesel for surface operations, making it almost a midget submarine. The crew compartment will, however, be 'wet', although the crew will be able to conserve their underwater breathing apparatuses by using built-in breathing sets. The 'cab' will have a computer-controlled system--including an automatic pilot to reduce operator workload. It will also feature a telescopic mast with a television camera and possibly a thermal imager. The vehicle will have a range of 100 nautical miles (185 km) at four knots down to 50 metres, but on the surface the diesel will give it a maximum speed of around 20 knots.

Details of the planned Class 8 design are limited but it will apparently be eleven metres long, propelled by two eight-kW motors and powered by a lithium-ion battery. This will give a range of 50 nautical miles (93 km) at five knots, with a maximum speed of six knots. It will carry a six-man team, have a crew of two and, like the Class 6, will have built-in breathing sets.

One unusual vehicle for delivering special forces is the KSA SSK 96 Subskimmer, which is a 1.52-tonne rigid inflatable boat that can carry a two-man crew and two divers, the vehicle being capable both of surface operations and underwater. It is powered by a 90 hp Yamaha three-cylinder outboard motor in a water-tight engine compartment.

For underwater operations, a section of the hull is partially or wholly deflated by an electric pump and a centrally placed buoyancy tank can then be filled in an operation which takes between 14 and 90 seconds. Flexible electric propulsion units near the bow are powered by lead-acid batteries and the vehicle can be left on the sea bed for periods of up to several days. The Subskimmer can also be operated awash with a snorkel supplying the engine with air.

The vehicle has a cruising speed of 20 knots (maximum speed of more than 25) while the surface range is 70 nautical miles, although this can be increased with extra tanks. The Subskimmer usually operates a crew of two with up to 300 kg of stores and it is in service with a number of countries including Thailand.

For longer-range operations the SDV is usually replaced by the midget submarine. Larger versions of the SDV, such as the EMT Class 6 and the Columbia Dolphin may blur the distinction between the two, but the midget submarine not only tends to have longer sea legs but the personnel are in a dry environment. However, 'dry' is a relative term, and these small vessels tend to be effected by condensation due to several people living in close proximity within a confined space. A floodable chamber allows personnel to enter and to leave the submarine.

Italy's Cosmos has been foremost in developing commercial designs that have been used not only for special operations but also to provide in miniature the capability that was expected from a conventional diesel-electric submarine. The MG 120/ER, for example, is described as a Shallow Water Attack Submarine (Swats) that was originally designed for special operations but has since had its roles expanded through the addition of improved sensors and the capability to conduct anti-ship operations.

With a submerged displacement of 130 tonnes it is capable of 1600 nautical miles (2960 km) at seven knots on the surface and 60 nautical miles (111 km) at 4.5 knots submerged. It is also available with an air independent propulsion system based on a closed circuit diesel fuelled by liquid oxygen, which provides an underwater range of 400 nautical miles (740 km).

The vessel has a crew of six and can carry a team of up to 15 and two Cosmos CE2F/X100 with 20 limpet mines. But the two 53-cm torpedo tubes mean it can also carry two heavyweight torpedoes and two spare. It is used by several navies in Eastern and Western Asia as well as Latin America.

The manufacturer has improved the concept with a new design as the X 201, a 200-tonne vessel with a surface range of 2500 nautical miles (4600 kin) at 15 knots and can operate down to 200 metres. The X201 can carry six torpedoes or two SDVs as well as up to twelve special forces personnel. Cosmos, based in Leghorn, went bankrupt in March 2004 following the involvement of its owners in the Iraqi Oil for Food scandal.

A derivative of another Cosmos design has been built by the Pakistan Navy as the MG 110, with a submerged displacement of 110 tonnes. The performance and weapon load are similar to the MG 120 but it can carry eight special forces personnel.

The former Yugoslavia produced the Una class midget submarines. A Yugoslav-based design has certainly been used by North Korea (and exported to Vietnam as well as Iran) to land special forces operatives as one of these so-called Yugo boats became stranded in South Korean waters in 1998. They have a submerged displacement of 90 to 110 tonnes and a surface range of 550 nautical miles (1020 km) at ten knots and a submerged range of 50 nautical miles (92.5 kin) at four knots. It is operated by a crew of four and carries about half-a-dozen special forces, and the weapon load can include two lightweight (40 cm) torpedoes.

By contrast the 60-tonne (submerged) displacement Northrop Grumman Electronics Sensors and Systems Division, Oceanic Systems Advanced Seal Delivery System (ASDS) is designed to deliver up to 16 special forces personnel. Powered by silver-zinc batteries and using retractable thrusters the vessels are capable of about 125 nautical miles (230 km) at eight knots and it can operate down to 60 metres.

The ASDS control system includes multifunction displays, an inertial navigation system identical to that of the F/A-18 Hornet, forward- and side-scan sonars as well as dual-redundancy control computers. Improvements include the introduction of lithium-ion batteries and new assemblies for the bow and stern.

RELATED ARTICLE: Clockwork Special.

Special operation fighters can make use of a myriad systems to fulfil their missions--from the largest to the smallest and to the most anonymous. Macroswiss a fairly new company specialising in surveillance and covert operations equipment, has recently developed an underwater version of its Giraffe recently and quite successfully tested by the US Marine Corps (4th Marines) over a period of six months. The Giraffe consists of a telescopic aluminium pole that can expand to a length of 5.5 metres and at the tip of which is affixed a miniature camera that conveys real time images to a chest-carried display. This enables one to very discretely watch <<what's going ore, over walls, behind even second-floor windows, or even search down sewer manholes for suspect items. Macroswiss has recently developed an underwater version that can be used down to depths of 70 metres, including its display.

The anonymous, in such circumstances, are connectors. For instance in the case of this Delftjet underwater propulsion system, disaster could strike if for any reason the connector between the battery pack and the motor could fail. A connector is an item that is often brutalised and tampered with during endless plug-in/unplug manipulations, but must yet give flawless service at all times--and in this case also remain waterproof. This is the gauntlet raised by another Swiss company, Fischer Connectors, that produces connectors for medical pacemakers as well as for the military. See the <<What's Up>> section in the main issue of this magazine.
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Title Annotation:Complete Guide
Author:Hooton, E.R.
Publication:Armada International
Date:Dec 1, 2005
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