The Gotland class is one of the most praised non-nuclear submarines.
Yet, even though it has many innovative design features and superior capabilities, no country
other than Sweden has preferred this silent underwater hunter.
Why?
As the Weapon Detective, we are now investigating the Gotland-class submarines and the answer
to this question.
The Gotland class, a.k.a.
A19-class, is among the best diesel-electric submarines.
One of them, HMS Gotland, even sent a shiver up/down the U.S. Navy's spine.
Despite everybody's admiration, no export success has been achieved.
Before seeking an answer to this question, let's briefly look at the history and features
of the Goland class first.
Before we start, we would like to thank kris tis for his generous donation to our channel.
On February 4, 1958, the Swedish Riksdag passed the Defence Act of 1958, which gave priority
to the army and air force.
Stockholm reduced to navy's share in the defence budget from 18 to 12 per cent.
Sweden would gradually replace the major surface combatants with the fast attack crafts in
the anti-surface warfare mission, while submarines would become the backbone of anti-submarine
warfare missions.
But the existing vessels were insufficient for the new mission definition.
So, Stockholm authorised Marinplan 60, which initiated the commissioning of a new and highly
capable submarine and torpedo boat.
One part of this plan was the construction of Sjöormen-class submarines.
During the design phase of this class, Sweden also evaluated the use of an air-independent
propulsion system, shortly AIP.
But due to technical difficulties, time constraints and high development costs, the Sjöormen
class was ultimately built with conventional battery-powered machinery in underwater mode
and diesel propulsion in surface mode.
The Sjöormen class had a teardrop hull shape and bow planes on the fin/sail, and their
stern diving planes were configured in an X-shape.
These design features would be typical for the later Swedish submarines.
In 1982, Sweden began the study phase of a new submarine programme to replace the Sjöormen
class.
Initially, these vessels, called the Gotland class, would be the only an-improved variant
of the Västergötland class.
Even when Stockholm ordered them on March 28, 1990, they were still conventional diesel-electric
submarines without AIP.
However, the works on an AIP powered by Stirling engines had already grown in maturity in the
late 1980s.
Between 1987 and 1988, HMS Näcken had been cut in half, and an 8-metre-long hull section
containing a prototype AIP using a closed cycle Stirling engine had been installed between
the aft battery/propulsion room and the engine/motor room.
This technology increased submerged endurance to 14 days.
So, Sweden decided to equip the Gotland class with an AIP on September 5, 1991.
The Swedish Riksdag approved the budget for the redesigned submarines in 1992.
Initially, Sweden had planned to have five Gotland-class vessels.
But due to increasing costs and the end of the First Cold War, only three submarines
were ordered.
The first of its class, HMS Gotland, was laid down on October 10, 1992, launched on February
2, 1995, and commissioned on September 2, 1996.
HMS Uppland was laid down on October 21, 1994, launched on February 9, 1996, and commissioned
on October 1, 1997.
HMS Halland was laid down on January 14, 1994, launched on February 19, 1996, and commissioned
on May 1, 1997.
The hull design of the Gotland class highly resembles the previous Västergötland-class.
The fin/sail is the same as that of the Näcken-class.
Thanks to the X-shaped rudder design of the Gotland class, all four control surfaces can
be used for both turning and depth control.
Along with two bow planes on the fin/sail, they allow sharp turns and enable the ability
to operate very close to the seabed.
The hull design of the Gotland class reduces acoustic and infrared signatures and active
sonar response.
Also, the submarine's machinery is isolated and mounted on rubber dampeners to minimize
vibrations and noise.
It has a degaussed hull, which is also covered by various types of coatings.
The mast is also coated with radar-absorbent material.
A conventional blade propeller produces steam bubbles because of frictional heat when it
rotates at high speed.
When these bubbles pop, they make noise.
It is called cavitation.
When the Stirling AIP is engaged, the propeller turns slowly, which prevents cavitation.
The Gotland is the first operational submarine class with a Stirling engine AIP, which extends
its submerged endurance from a few days to weeks.
Only nuclear-powered submarines previously had this capability.
The 100 horsepower V4-275R Mk.2 Stirling AIP of the Gotland class is the improved variant
of the Mk.1 used on the HMS Näcken.
The Stirling engine AIP of the submarine works as follows; a combustion reaction between
liquid oxygen stored in a tank and kerosene fuel generates heat to approximately 800 degrees,
which is transferred to helium gas through a heat exchanger, expanding it, and cooling
it with seawater.
The Gotland-class submarines can carry 24 tons of liquid oxygen.
So, they can cruise underwater for 14 days at 5 knots speed without snorkelling.
A nuclear reactor needs a constant cooling system operating at all times.
So, using the surrounding seawater as a heat sink in a Stirling engine increases efficiency.
The pumps of a nuclear reactor's cooling system produce noise.
On the other hand, since a Stirling engine does not require such a system, it is quiet
and vibration free.
During the surfaced cruise, the two diesel engines are engaged.
Thanks to the high automatization, the Gotland class requires a small number of crew members.
For example, a single operator can steer the submarine in depth and course.
A smaller complement leads to good accommodation standards and low operating costs.
The Gotland class has the SESUB 940A combat management system, whose derivative, the SESYM,
is also used on the Gävle-class corvettes.
The submarine can manage 272 targets, 95 of which can be tracked simultaneously.
The fire control system of the Gotland class can control several torpedoes simultaneously.
The armament consists of four 533mm and two 400mm torpedo tubes.
The submarine can carry up to 12 of these torpedoes.
The 533mm wire-guided/passive homing Tp 613 torpedo is effective against both submarines
and surface targets.
It has a speed of 45 knots and a maximum range of 30 kilometres.
Its warhead weighs 240 kilograms.
The maximum range of the 533mm Tp 62 is over 50 kilometres.
It can be used against the target at 500 metres deep.
The torpedo with a 130-kilogram warhead has a pump jet propulsion system giving it a maximum
speed of over 45 knots.
It can also track several targets and classify them at the same time.
The Tp 62 can also share these data with the submarine simultaneously.
The Gotland class can also launch the 400mm Tp 45 lightweight anti-submarine torpedoes,
whose maximum range is 20 kilometres and speed is 50 knots.
It has a 45-kilogram warhead.
The submarine can also lay sea mines.
The operational diving dept of the Gotland class is 150 metres.
The complement of the Gotlands class is 27-person.
The submarine has a length of 60.4 metres, a beam of 6.2 metres, and a draught of 5.6
metres.
Its surfaced displacement is 1,526 tons, while its submerged displacement is 1,647 tons.
The propulsion system consists of two 1,300 horsepower MTU diesel engines and two 100
horsepower Kockums V4-275R Stirling engines.
Its maximum surfaced speed is 10 knots, while its maximum submerged speed is 20 knots.
HMS Gotland and HMS Uppland were already subjected to mid-life modernization.
Sweden approved the same work for HMS Halland in 2022.
After modernization, these submarines have 50 improved systems.
More than 20 of these systems are the same as the planned A26 class, a.k.a.
Blekinge class.
In this way, the Swedish Navy can test the subsystems of its future submarine.
Also, the crew of the Gotland class will have a chance for a smooth transition to the Blekinge
class.
The modernized Gotlands have the Mk.3 variant of the V4-275R Stirling engine, a new mast
suite, the Kongsberg SA9510S sonar, new sensors, and management and communication systems.
The submarine has also received the Excelis ES-3701 ESM.
To host all these subsystems, the Gotland class has gained additional 2 metres in length
and another 200 tons in weight.
In 2000, HMS Halland took part in a multi-national exercise in the Mediterranean.
Swedish sources claim that she could track many NATO surface combatants while remaining
undetected.
In the same year, HMS Halland participated another exercise in the Atlantic and won mock-up
duels against the Spanish naval units and the French and U.S. nuclear-powered submarines.
So, the U.S. Navy requested to lease HMS Gotland for one year for use in antisubmarine warfare
exercises in 2004.
After the governmental approvals were done, she sailed to the Pacific.
In 2015 and 2016, the submarine managed to penetrate the defensive measures of a U.S.
carrier strike group and snap several pictures of the aircraft carrier USS Ronald Reagan.
So, why no country has preferred the Gotland class, which has proved it can defeat NATO
naval forces, including the U.S. Navy?
The superior capabilities of the Gotland class did not cause these achievements alone, but
again the inadequacy of the anti-submarine warfare capabilities of the modern fleets
determined the result.
During an exercise in the Caribbean Sea in 2001, the German Type 206-class diesel-electric
submarine U-24 won a mock-up victory against the carrier USS Enterprise by firing flares
and taking a photograph through her periscope.
Besides, in 2016, a Walrus-class submarine of the Royal Netherlands Navy tracked the
Russian carrier RFNS Admiral Flota Sovetskogo Soyuza Kuznetsov without being detected for
a long time.
As mentioned in our many videos, the countries are conventional about their arms suppliers.
Even while less capable diesel-electric submarines can threaten modern surface fleets, who wants
to change its traditional supplier for a more advanced yet more expensive vessel?
And these traditional suppliers, such as Germany and France, also offer AIP submarines, which
have similar combat capabilities as the Gotland class.
The Stirling AIP makes the Gotland class one of the best submarines.
So, Australia and Japan preferred the engine, not the vessel.
From this perspective, we may say that Sweden has managed the find new customers, which
is a big market success.
Yes, Australia will retire the Collins class soon.
But the problem is not the Stirling engine; it is the vessel's design.
Although it is efficient, Japan gave up the Stirling engine in favour of lithium-ion battery
technology, which is simpler and cheaper.
Besides, who wants to defeat NATO naval forces, especially the U.S. Navy?
And do you think Sweden desires to sell its Gotland-class submarines to those countries?
Would the Swedish Riksdag approve of such an arms deal?
So, according to our analysis, the conservative customers in the international defence market,
the powerful traditional rivals, and the political situation have prevented the sales success
of the Goland class.
Also, many former diesel-electric submarines still pose a formidable threat to modern surface
fleets.
So, the Gotland class was just born at the wrong time, in the wrong place and in the
wrong situation to be successful in the international market.
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