Finnish Post-WW2 Submarines

[General Tirpitz]

The Paris Peace Treaty in 1947 forbade Finland from having submarines but what if that hadn’t been a case? I’m mainly interested in following questions:

What would have the post-war submarine fleet looked like? Not surprisingly, the navy’s early plans had called for small, short-range submarines. The first plan for the post-war navy in 1946 called for two submarine viirikkö (a Finnish term meaning a small group of two or more ships) located in Southwestern Finland and Western Finland respectively. Overall plans called for 6-8 submarines. Interestingly, in plans made in 1949, after the peace had been signed already, the navy created a “maximum plan” which called for ten submarines and ten miniature submarines. The navy commander at the time had also suggested that Finland should have 5-6 submarines. It seems that by the 1950's the navy finally gave up with submarines and didn't give them anymore much thought.

Where could Finland had gotten those submarines? Or could we had even built them by our own? While Finland own five submarines were already old-fashioned in the late-1940’s, the navy did hope that it could take them into use again. At least Vesikko, the newest one, was planned to be used as a training ship. It’s rather questionable how much of use they would have been in combat situations in the early 1950’s anymore though.

What sort of role could submarines have had in naval planning? During wars, their main task had been mining and interfering with Soviet merchant shipping in the Baltic Sea. During the late-1940’s and the early 1950’s Finnish military plans considered a possible Western attack to Finland but this threat got less attention later on as the military started to focus on the Soviets. What sort of role would submarines had played in planning against the Soviet Union?

 

[DrakonFin]

Where could Finland had gotten those submarines? Or could we had even built them by our own? While Finland own five submarines were already old-fashioned in the late-1940’s, the navy did hope that it could take them into use again. At least Vesikko, the newest one, was planned to be used as a training ship. It’s rather questionable how much of use they would have been in combat situations in the early 1950’s anymore though.

What sort of role could submarines have had in naval planning? During wars, their main task had been mining and interfering with Soviet merchant shipping in the Baltic Sea. During the late-1940’s and the early 1950’s Finnish military plans considered a possible Western attack to Finland but this threat got less attention later on as the military started to focus on the Soviets. What sort of role would submarines had played in planning against the Soviet Union?

Having recently looked into Finnish missile purchases in the 60s and 70s, I think the only realistic options for 1945-1990 might be Finland buying Soviet-made submarines or building their own. That Finland could restart using submarines at all would need a reinterpretation of the Paris Peace Treaty, and that would mean getting both the West and the East to agree on it. If submarines are seen in any way like missile weapons, the West would be sceptical of the Finnish project as the US and the British would think that any submarines Finland gets would in the case of war used to support the Soviet Navy in the Baltic, against NATO vessels. Finland was seen as too closely linked to the Soviets to be able to resist Soviet pressure if push came to shove. The Soviets, on the other hand, might even be positive towards Finnish submarine projects, provided the submarines or at the very least their torpedo armament is bought from the USSR.

So, maybe Finland could make a deal over smaller diesel submarines, in the vein of the Whiskey, Quebec and Romeo Classes. Just buying a Soviet design and building Finnish versions of it at domestic shipyards could be an option. Either way, I can't in any case see the Finnish Navy having a fleet of more than five submarines. Perhaps a one class of three circa 700-1300 ton vessels would be likely. The biggest obstacle would be money, and I am having a hard time seeing where the kind of money and political will to build or buy these vessels would come from. The Navy was starved of resources and money in the 50s and 60s as it was, and buying or building surface vessels would be seen as more important. If the choice has to be made between building three "Hylje Class" submarines (think a slightly enlarged Quebec Class coastal sub) and two or three corvette-sized gunboats in the vein of the OTL Turunmaa Class, the surface vessels would be seen as the priority.

One thing the submarines would compete with would be the Navy's anti-ship missile project. If it is decided to put resources into submarines, the Navy might forgo obtaining missile boats in the 60s and 70s. There would have to be more resources put into torpedo development and introduction, as in the 50s-60s IOTL the torpedo weapon sort of fell by the wayside due to the peace treaty restrictions and limited resources. A postwar Finnish submarine TL would see more effort on torpedos, also for surface ships. The domestic electric torpedo project might be more successful. On the other hand, there would probably not be missile boats at all, and even the coastal artillery's missiles might be limited into short-range weapons like the OTL RO-63. If the Navy and coastal artillery don't adopt a true anti-ship missile in the 60s and 70s, the Finnish Navy's missile projects might only get started after the USSR falls, with western weapons instead of the OTL Soviet missiles. All the experience gained in using (and developing) missiles from the MTO-66 to the MTO-85, as well as building domestic missile boats would not be there, but then the Finnish Navy would have been much more knowledgeable about submarine and torpedo matters. Slowing down the missile developments would give something of a lease of life for the traditional coastal artillery, and phasing out the coastal forts might be pushed forward a couple of decades.

In terms of planning, submarines would provide the Finnish fleet reach, the ability to attack a invading enemy somewhat further out before they closed up to the minefields and various land-based coastal defences. IOTL, after the early 70s, this was a role given to the missile boats that were (in the kind of thinking represented by Jouko Pirhonen as the commander of the Navy, say) to attack the enemy's bigger vessels from the cover of the archipelago. IOTL, the abandoned Tuuli Class hovercraft was in my view the culmination of this line of thinking - conceived as a fast, missile-armed "archipelago interceptor".

IOTL, there was a project to acquire submarines for the Finnish Navy in the 90s, in cooperation with the Swedish. It fell through because of there not being money for it. In a TL where Finland had Soviet subs or domestic subs based on Soviet designs, it is pretty likely that in the 90s or 00s the Finns would then seek to modernize their submarine fleet by buying Swedish boats or using Swedish designs for a new domestic submarine class.

I'll have to look into this all to get more insight, so maybe I'll get back to you.

 

[Jukra]

What sort of role could submarines have had in naval planning? During wars, their main task had been mining and interfering with Soviet merchant shipping in the Baltic Sea. During the late-1940’s and the early 1950’s Finnish military plans considered a possible Western attack to Finland but this threat got less attention later on as the military started to focus on the Soviets. What sort of role would submarines had played in planning against the Soviet Union?

In case of Finnish defense spending being at OTL level the main use of submarines would have been to prevent other Navy acquisitions. Submarines were and are expensive. But let's try a TL:

POD 1: Paris Peace Treaty does not omit submarines and magnetic mines from Finland, Britain simply forgets the issue.

Finnish submarine arm during 1950's: The Beginning

Submarine "Vesikko" (Prototype of German Type II -class) was reconditioned and refurbished for 1952 training season as Fast ASW target. This means streamlined hull and conning tower, snorchel and more battery capacity. Schnorchel conversion was somewhat unsuccesful resulting the "Vesikko" nicknamed as "The Eardrum Popper." The conversion is rather rudimentary but judged as good enough. Finnish officers are also sent to Sweden for submarine training.

Second Step: H-class

Like other arms purchases during late 1950's, economic factors were a primary driver. British surplus equipment was readily available, politically uncomplicated and credit could be arranged. Thus four V-class submarines were bought in 1956 and, after small modernization with schnorchel, slightly remodeled conning tower and some battery capacity., entered in service in 1957-1958 as "Halli", "Hylje", "Hauki" and "Harjus". In mid-1960's they entered more radical modernization inspired by Swedish "Abborren II" program.

Each season two of the boats were operated and two were kept in reserve. In addition to torpedo attack and minelaying duties the boats were extensively used to deploy, support and supply combat divers. Unconventional warfare was all the rage in Finnish Defense Forces during 1960's. The secret wartime tasks for the boats in case of Soviet surprise attack did include, if conventional defense failed, support of resistance movement in Finnish mainland and archipelago. Submariners considered themselves to be the elite arm within the Navy.

The most dramatic deployment of the boats was in Autumn of 1968 when both active boats (Halli and Hylje) were deployed to recon and guard against possible Soviet intervention.

Third Step: Into Kekkoslovakia

By early 1970's Finnish Navy submarine arm was well developed and appreciated combat arm. The old submarines needed replacement and the Finnish maritime industry was well equipped to produce, although not to design, their replacement. Finnish Navy together with Rauma-Repola shipyards contacted British and Swedish firms for design aid and in order to guarantee left-wing support for the project decided to buy Soviet torpedoes. This was a good opportunity to gain intel on them, as well.

The resulting four boat class "Inari", "Saimaa", "Päijänne" and "Pyhäjärvi" could be shortly described as small "Sjöörmen" -class with British electronics and Soviet torpedoes with curious and definitely not allowed German influences by Type 206 -class. With surface displacement of some 600 tons "Inari" -class entered service in 1976-1980.

 

[Jukra]

Fourth Step: Pirate hunting and deep strike

Rauma-Repola managed to sell eight "Inaris" to Imperial Iran but deal fell through due to Islamic Revolution. Rauma-Repola had hard luck as Libyan sale was put down due to American pressure and Iraqi sale did not materialize due to delays in payment and finally, due to 1991 Gulf War. Yugoslavian interest did not materialze to substantial level and North Korean interest was kindly declined by Finnish Ministry of Foreign Affairs.

While "Inari" -class small submarines were well suited to Finnish waters their small size meant small flexibility in weapon use and their short endurance restricted both peacetime and pre-crisis operations. Small boats also could not fully utilize new AIP propulsion methods. Thus already during 1980's the Navy had decided the replacement class should have larger size for larger endurance and more flexibility in operations.

Sweden was contacted for co-operation and some initial sketches were made during late 1980's for joint post-Gotland class, "U-båt 2000". After end of the Cold War Norway and Denmark joined the project as well in Nordic sub project "Porpoise" (Originally called Viking, but as in Finland vikings were historically heralded as targets a new name was decided.). After some pains during the development project, including Denmark leaving the project, the three Finnish subs "Vetehinen", "Vesihiisi" and "Iku-Turso" entered service in 2007-2013. They have been active in Operation Atalanta.

A new, and somewhat controversial task for Finnish submarines has been the deep strike mission. Finnish Navy purchased 30 MBDA Scalp Naval (MdCN) cruise missiles "in order to establish a deep strike capability to support joint warfighting". This has been critcized as duplication as the Air Force operates JASSM cruise missiles as well, but on the other hand this distribution assures Finnish strike back capability in event of surprise attack which manages to eliminate the Air Force.

(Porpoise is an ATL version of this OTL project)

https://en.wikipedia.org/wiki/Viking-class_submarine