• Forum
• SITREP

• Military

• Introduction
• Systems
• Facilities
• Agencies
• Industry
• Operations
• Countries
• Hot Documents
• News
• Reports
• Policy
• Budget
• Congress
• Links

• WMD
• Intelligence
• Homeland Security
• Space
• Public Eye

Further Reading

A19 Gotland

With her Stirling AIP (Air Independent System), Swedish Navy submarines are able to remain submerged for weeks at a time, without having to surface and thereby risk detection. The Stirling system is an important element of the overall stealth concept. Much else is involved, however, such as various forms of signature reduction and the elimination of noise.

Typical missions include anti shipping operation, anti submarine warfare missions, forward surveillance, special operations and minelaying. Gotland class submarines can carry a powerful range of wire-guided and homing torpedoes, missiles and mines. The Gotland class is the world's first conventional submarine designed specifically to incorporate an AIP system. This, combined with low underwater signatures and target strengths, ensures the ultimate in underwater stealth. The Gotland class can operate independently of any major infrastructure facilities ashore. The fuels used is widely available and weapons can be reloaded with the aid of a small crane, giving the Gotland class a very high operational value.

A very high degree of automation and remote control enables the Gotland class to operate with a relatively small crew. This not only minimises operating costs: it permits a higher standard of crew accommodation. The Combat Management System handles detection, identification, weapons launch and control at distances well beyond the horizon. All weapons can be launched in rapid succession and guided simultaneously toward individual targets. The Combat Management System includes an effective sonar suite with circular, intercept and flank arrays. The Gotland class also possesses extremely high shock endurance, enhancing survivability.

A study phase started in 1982 in order to substitute the Sjöormen class sub-marines. In 1990 FMV signed a contract with the Swedish company Kockums for aquisition of three new submarines. After delivery from Kockums, FMV carried through extensive test activities in 1996 - 1997. In 1997 Kockums completed building three Gotland (Type A 19)-class boats to replace the Sjöormen-class boats built in the 1960s. The Swedish Defence Materiel Administration (FMV) handed over the three Gotland class submarines "HMS Gotland", "HMS Uppland" and "HMS Halland" to the Swedish Armed Forces in Novmber 1998.

In the context of the new rapid reaction force, the submarine's multi-mission capability is especially useful, as is the ability to operate unseen. In particular, the submarine has developed into a superb surveillance platform, which can see and hear over huge distances while able to remain undetected.In the strictly naval context, the submarine is also well suited to operate as a subsurface command centre. Another advantage is that submarines permit great freedom of action, when the decision to act is restricted by political uncertainty. The fact is that submarines operate mainly in international waters. And high-risk operations can be conducted on a clandestine basis.

These submarines are conventional submarines equipped with a machinery (Stirling) which is independent of air supply. This allows the submarines to operate submerged throughout several weeks, a fact that makes these submarines unique.Compared with other submarines the Gotland class is a relatively small submarine, containing long endurance and advanced technology and it is probably the most silent of today's conventional submarines. Shortly - the Swedish Armed Forces today have three of the most modern conventional submarines in the world.

The main roles envisaged for the Gotland boats are attack, surveillance, minelaying and ASW. Externally the single-hull Gotland is very similar to the Södermanland class (Type A 17), but has improved performance in submerged endurance, and with increased stealth capability afforded by anechoic tiles that are fitted to the hull. All equipment is resiliently mounted and major platform decks and all equipment are carried on rubber mountings to isolate them from the hull.

The hull is divided into two watertight compartments separated by a tank section, which incorporates a one-man escape chamber accessible from both compartments. A DSRV or a rescue bell can be mated to the chamber. The forward compartment is divided into two decks, the lower deck housing the four 533 mm and two 400 mm bow torpedo tubes and associated weapon handling gear and reload racks. Beneath this compartment is the battery space and auxiliary machinery. The upper deck houses the control room, accommodation and other equipment rooms associated with the sensors and communications. The aft compartment houses the diesel generator sets and more battery space, as well as auxiliary machinery and propulsion control equipment. This aft section also contains the Air-Independent Propulsion (AIP) machinery and electric motor. In the aft section are installed two Stirling V4-275R AIP Mk 2 systems developed by Kockums using liquid oxygen and diesel in a helium environment.

The submarine is equipped with two MTU diesel engines and two Kockums V4-275R Stirling Air Independent Propulsion units. The Stirling engines are mounted in elastic, soundproof modules and each provide up to 75 kW. The submarine has the capacity for two weeks of air independent propulsion at a speed of 5 knots without snorting. The AIP uses liquid oxygen and diesel fuel in a controlled inert (helium) environment. The AIP liquid oxygen tanks are located on the deck below the engines. The propulsion system provides a speed of 11 knots surfaced and 20 knots dived.

The Gotland is manned by a complement of 28 crew and 5 officers The submarines are fitted with four 21 inch torpedo tubes taking the Bofors Torpedo 2000, and two 15.75 inch torpedo tubes taking the Bofors Underwater Systems Type 613 torpedo. The Gotland can also be used to deploy the Bofors Underwater Systems stand-off self-deployed Mine 42. The submarine also has the capacity to carry 48 mines mounted externally in a girdle arrangement. The ship's combat management system is the 9SCS Mark 3 from CelsiusTech. The system carries the Swedish Royal Navy designation SESUB 940A. The system uses an extended version of the ADA software from CelsiusTech's 9LV Mk 3 surface ship combat management system.

The fire control system has the capacity to control several torpedoes in the water simultaneously. The new application software includes target motion analysis developed by Kockums and the University of Lund at Malmo. Kockums have also been responsible for the development of enhanced software for navigation, for torpedo tube control and torpedo tube simulation. The 9SCS Mark 3 Combat Management System has three multifunction consoles, Type IID from Terma. The terminals are for command and control, communications, and weapon control. The consoles are connected via a dual Ethernet copper wire local area network. The combat management system receives data from the submarines' sensors. The submarine is equipped with a CSU 90-2 integrated sonar sensor suite from STN Atlas Elektronik. This includes a passive cylindrical bow array, an intercept array and two passive flank arrays. The sonar system uses ADA software. The submarine is equipped with a Kollmorgen search and attack periscope and a Terma Scanter navigation radar.

The electronic support measures system is the Racal Thorn Manta radar surveillance and warning system as deployed on the British Royal Navy Oberon and Churchill class submarines. Manta carries out surveillance, detection, analysis, classification and identification of hostile radar threats from D-band to J-band. The Manta system also provides a prediction of the detectability of the host submarine by the threat radar using a combination of data from the hostile radar frequency, the sea state and the configuration of the submarine's periscope assembly.

For two years the Swedish Navy submarine HMS Gotland, built at Kockums, was leased to the USA, complete with a Swedish crew. The Swedish submarine participated in intense and demanding exercises off the US coast, for which she gained great respect and won the praise of professionals worldwide. HMS Gotland was in the USA since June 2005, operating out of the USN's San Diego naval base, on the west coast. In June 2006 the Swedish Government approved a US request that the Swedish Navy submarine HMS Gotland be allowed to extend its stay in the USA by a further twelve months, to conduct exercises with the US Navy, as well as with the Royal Canadian and Royal Australian Navies. HMS Gotland had performed extremely well in these joint exercises so far, and has impressed both the experts and the professionals who are monitoring her success.

The training areas lie some 100 nautical miles off the US coast, where the depth varies between 1000 and 2000 metres. The entire area is equipped with microphones and underwater telephones. The vessels the Swedes have been matched against include Arleigh Burke-class destroyers and Ticonderoga-class cruisers. The submarine has also participated in manoeuvres with the P 3 Orion ASW aircraft and the Sea Hawk ASW helicopter, the F 18 Hornet strike aircraft and the Ronald Reagan aircraft carrier, class Nimitz (CVN-68). The Swedish vessel managed to evade detection on several occasions.

Kockums personnel have made a number of trips to the US to maintain the vessel between exercises. On one occasion, 35 specialists from Kockums' support and maintenance team flew to San Diego to carry out a thorough overhaul, over a period of several weeks. During the first twelve months, HMS Gotland was at sea for more than 160 days. During these exercises, as well as having to evade the attentions of a range of US Navy units, she also had to deal with those of airborne units. The exercises in which she participated during the second year of her lease were equally challenging.

Her Stirling AIP (Air Independent Propulsion) system, which enables a conventional (non-nuclear) submarine to remain submerged without having to surface and risk detection, has played a decisive role in her success. In exercises conducted with the US Navy, as well as with naval units from Australia and Canada, she performed superbly and proved extremely difficult to detect. She has also surprised her hunters in many other respects during these joint exercises. The performance of her Swedish crew was excellent, for which it has been warmly commended. The vessel's stealth capabilities have been highly praised. She is neither heard nor seen, appearing without warning and surprising her hunters. Participation in these exercises has naturally provided the Swedish crew with considerable additional experience, which will prove particularly valuable in future international operations. The series of joint exercises was concluded by mid-2007, at which point HMS Gotland returned to Sweden.

In the February 2009 issue of the respected Armed Forces Journal, Professor Mikan Vego of the US Naval War College proposes that the US Navy complement its force of nuclear submarines with a number of conventional submarines. This proposal derives from expectations that the US nuclear submarine force will be reduced over the next 15 to 20 years, and that conventional submarines are better suited for shallow-water missions, as in the littoral zone off the US coast. It is precisely these zones that are currently subject to the greatest threat, throughout the world.

Professor Vego points to Kockums' Gotland-class submarine as one of two main candidates in the field of advanced conventional (non-nuclear) submarines. The Gotland class is described as exceptionally manoeuvrable, silent-running, difficult to detect and tough, with the ability to remain submerged for weeks at a time. HMS Gotland also enjoyed considerable success during the two years in which she was leased to the US with a Swedish Navy crew. Her performance gained the attention of naval and industry professionals throughout the world.

Compared with other conventional submarines of similar capabilities, the Gotland class comes with an attractive price tag, notes Professor Vego. According to him, a Gotland-class submarine costs almost 30 percent less than other comparable submarines. And the Gotland class also possesses better stealth characteristics.

Main characteristics: Displacement 1495 tonnes Length overall 60,5 m Diameter of the hull 6,1 m Weaponry 4 tubes for heavy torpedos type 613, 62 2 tubes for torpedos type 43, 45 Crew 25