The Turunmaa-class gunboat, which is internationally defined as corvette, is generally overlooked,
but it is a historically noteworthy warship.
FNS Turunmaa and FNS Karjala, two vessels of this class, attracted international attention
with their state of the art propulsion systems and electronics of their time.
Still, they were bizarre in many ways.
Now, we are investigating the Turunmaa-class, the first major surface combatant designed
and built by Finland after the Second World War.
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The Turunmaa-class, which we will call it corvette like its international classification,
was an unusual surface combatant.
It was a small naval vessel with a big gun for the rest of the world.
On the other hand, given the 1960s it was built, it was a warship that could be considered
large for Finland.
To better understand the Turunmaa-class, we should look at the political condition of
this country at that time and the rooted gunboat tradition of the Finnish Navy.
After the Second World War, Helsinki quickly realized that it could not trust the war-weary
western countries' military aid in case of a possible Soviet invasion.
But, Stalin did not want an adventure over Finland.
Keeping Finland as a buffer zone with the West was a preferable choice for Moscow.
So, a neutral Finland was the best solution for all parties.
Still, the USSR could not allow this country to have a sizable military power.
Thus, the 1947 Paris Peace Treaties limited the Finnish Navy to a fleet of no more than
10,000 tons and 4,500 men.
Also, this naval force would not have weapon systems, such as torpedoes, submarines, mines
and missiles.
So, Finland reorganized its navy based on the limitation.
Helsinki acquired frigates from both the Eastern and Western blocs.
But, the Finnish naval staff knew that the big warships were not suitable to protect
the country's maritime interests.
Especially considering the restrictions, the navy would have only a small number of them.
Also, the big ship meant deeper draught.
On the other hand, the Finnish maritime interests were on the shallow waters.
The Finnish Navy's experiences of the Second World War had proved that the lightweight
gunboats were quite versatile.
They had successfully performed anti-surface warfare, submarine hunting, escorting, providing
fire support for ground troops, minelaying, and minesweeping missions.
These vessels had even acted as motherships for the submarines.
So, in the late 1950s, Finland decided to design and build indigenous minor and major
surface combatants in its local shipyards.
The first step of this plan was the 40-ton Nuoli-class gunboats.
Yet, these fast attack crafts had the 40mm guns at heaviest.
The previous Rihtniemi and Ruissalo classes with 23mm guns and 17-18 knot top speed were
still defined as minesweepers.
They would become the patrol boats in the late 1960s.
These under-gunned and small vessels did not have a change in a possible naval battle.
The Finnish Navy needed a warship with a bigger gun.
The Turunma-class was designed to answer this requirement.
The development of the corvette began in 1963.
The Finnish naval engineers worked on five different hull designs and over thirty propulsion
variants.
After the final design emerged, Helsinki ordered two ships in 1963.
The first ship of the class, FNS Turunma, was laid down in March 1967, launched on July
11, 1967, and commissioned on August 29, 1968.
The second corvette, FNS Karjala, became operational two months later.
The Turunmaa-class was the first and only Finnish-built modern major surface combatant
class after the Second World War.
Please remember that the construction of the Pohjanmaa-class corvette has not begun yet.
Finland classified the vessel as a gunboat.
Most probably, Helsinki did not take a risk to cause anxiety over Moscow by using the
term corvette.
But also, for the Finnish Navy, the term "corvette" was not familiar.
Yet the "gunboat" was an acquainted term.
There were some handicaps of the design of the Turunmaa-class.
First of all, the Finnish Navy had been organized for coastal operations to protect the archipelago.
The Turunmaa-class was too big for operating around the archipelago.
But also it was too small for the open sea.
The design studies of the Turunmaa-class had begun in the early 1960s when the big guns
were the most effective weapon system, which the Finnish Navy could get.
But, after a while, the restriction for the missiles and mines was lifted.
Thus, this country laid down FNS Isku missile-equipped training vessel in 1968, in the same year
the Turunmaa-class corvettes were commissioned.
Later, Finland decided to locally build four Osa-class missile boats, defined as Tuima-class.
So, the Turunmaa-class ships instantly became obsolete when they were commissioned.
Why did Finland not attempt to equip these corvettes with missiles?
Well, it would not be cost-effective.
Instead, Finland started a programme to develop a new indigenous missile boat, which would
lead to the Helsinki-class in 1976.
The high top speed was crucial for these corvettes.
So, the Finnish naval engineers preferred a narrow hull design.
But it caused steering difficulties.
Also, the slim design of the hull and superstructure made the ship crampy for the crew.
Still, as mentioned before, the Turunmaa-class attracted international attention with their
state of the art propulsion systems and electronics of their time.
It was one of the early examples of installing gas turbines in a small naval vessel.
The steel-hulled and flush-decked corvette weighed 700 tons at commissioning but gained
more than 100 tons during various upgrades.
Its superstructure was made of aluminium.
There were armour plates attached to critical areas.
The Turunmaa-class had the Vosper-Thornycroft roll-damping equipment.
One of the unusual features of these ships was that the large, tubular gas-turbine exhaust
trunks were led over the quarterdeck, discharging over the stern, with their plumes coalescing
some 15 metres abaft the stern.
According to Jane's Fighting Ships, this arrangement enabled the ships to be driven at around 12
knots without using propellers.
There are also many other rumours about the speed of the vessel.
Some say the Turunmaa-class with "war-time propellers" could reach a top speed of 60
knots.
But, for many sources, its recorded top speed was 37.3 knots.
Initially, they had both Eastern and Western electronic systems.
But, by the modernizations, the Western systems gradually replaced the Eastern ones.
For example, the Simrad hull-mounted sonar took the place of the Soviet-built MG-11 sonar,
whose NATO reporting name is Stag Hoof.
In 1985–86, Finland refitted both ships and updated the entire fire control and communications
systems.
The complement of the Turunmaa-class was 70-person.
The corvette had a length of 74.1 metres, a beam of 7.8 metres, and a draught of 2.4
metres.
Its fully loaded displacement was 770 tons.
The propulsion system consisted of one 15,000 horsepower Rolls-Royce Olympus TM1A gas turbine
and three 3,000 horsepower MTU MB diesel engines in CODOG configuration.
Its maximum speed was 35 knots.
The range was 4,630 kilometres, in other words, 2,500 nautical miles, at an economical speed
of 14 knots.
The armament of the Turunmaa-class consisted of one 120mm single-barrel TAK 120 mm L/46,
two 40mm single-barrel SAK 40L/70-350s and two 23mm twin-barrel ZU-23-Sako guns, and
two five-barrel RBU-1200 anti-submarine rocket launchers.
It also had the capability of launching depth charges and laying sea mines.
The water-cooled TAK 120mm L/46 was the naval gun variant of the Bofors FAK 120 X 53, which
was initially designed as a land-based anti-aircraft gun against high altitude air targets.
It was capable of firing 80 rounds per minute to a range of 18.5 kilometres.
The TAK 120mm L/46 had two feed tables, each holding six rounds, located on the sides of
the automatic loader and beneath the ammunition compartments.
It could be fed from either magazine, permitting the loading of two different kinds of ammunition.
The three-person crew consisted of one operator and two loaders.
For some former navy gunners, the TAK 120mm L/46 was the best naval gun in Finland.
But others claim that it had problems and was dangerous to use.
During training in 1970, the gun's barrel exploded, which caused minor injuries.
Finland used only anti-aircraft and shell-fragmented munitions with the TAK 120mm L/46 instead
of armour-piercing ones.
The Bofors 40mm SAK 40L/70-350 had a practical rate of fire of 300 rounds per minute.
Its maximum range was 12,500 metres against surface targets and 6,900 metres for air targets.
The TAK 120mm L/46 and SAK 40L/70-350 guns were equipped with electrohydraulic laying
machinery and was remotely controlled from a central fire-control system or an optical
director.
The I/J-band Signaal WM22 fire control radar of the Turunma-class could detect a target
at a range of between 30 and 32 kilometres and an altitude of 7,600 metres, in other
words, 25,000 feet.
It could track a target with a 1 square meter radar-cross section.
The radar could simultaneously engage one air and one surface target at 29 kilometres.
There was also the EOS-400 TV tracker/laser rangefinder fire director system on the ship.
The ZU-23-Sako was the Finnish-built naval variant of the ZU-23-2, and it had a practical
rate of fire of 200 rounds per minute for each barrel.
The range o these manually operated anti-aircraft guns was 2 kilometres for surface targets
and 1.5 kilometres for air targets.
The Finnish gave it the nickname "Sergei".
A common joke for this anti-aircraft gun was, "the Sergei doesn't even hit the barn door,
but there's nothing left of the barn walls".
The RBU-1200 anti-submarine rocket systems were in fixed mountings inside the main deck
superstructure.
The launchers were being taken out during the fire.
A full salvo was taking 12 seconds.
The RGB-12 rocket of the RBU-1200 was creating a kill-zone of ​​5 meters in diameter
at a depth of 300 meters.
It had a 34-kilogram warhead and a range of 1,200 meters.
Due to the neutral policy of Finland, the career of the Turunmaa-class was uneventful.
But, it was a significant vessel for the Finnish Navy.
These two corvettes were schools, where the whole generation of new officers learnt to
be seamen.
Besides, they trained more than 2,000 conscripts during their service time.
FNS Turunmaa and FNS Karjala also served as command ships for fast attack craft groups,
which consisted of the Nuoli-class motorboats first and then the Helsinki-class missile
boats.
The Turunmaa-class became the doom of the Finnish Riga-class frigates, locally designated
as Hämeenmaa-class.
As mentioned before, the 1947 Paris Peace Treaties had limited the human power of the
Finnish Navy to 4,500-person.
The commissioning of FNS Turunmaa and FNS Karjala caused personnel shortages.
So, Finland began to operate only one of its two Riga-class frigates at a time.
In 1979 FNS Uusimaa was decommissioned.
In the early 1980s, the Finnish Navy converted FNS Hämeenmaa to a minelayer first and then
retired the ship in 1985.
FNS Karjala made many naval visits to the ports of the Baltic and North Seas.
Her most distant sailing was to Norway, wherein 1982 participated in the silver jubilee of
the reign of King Olav V of Norway.
The Finnish Navy decommissioned its Turunmaa-class corvettes in 2001.
FNS Karjala is now a museum ship in the maritime museum Forum Marinum in Turku.
The Turunmaa-class symbolizes a significant leap for the Finnish naval shipbuilding capability.
Even though their weapon systems were already outdated when FNS Turunmaa and FNS Karjala
came into the world, they once managed to gain the world's admiration with their extraordinary
features.
The little-known Turunmaa-class deserve to be mentioned as a secret legend of naval history.
Thanks for watching our video.
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