Finnish submarine
Iku-Turso was a 500-tonne submarine that served in the Finnish Navy during the Second World War. It was launched in May 1931 and was named after a mythological Finnish sea monster, Iku-Turso. It was built by the Crichton-Vulcan shipyard in Turku according to a project developed by NV Ingenieurskantoor voor Scheepsbouw, "IvS", and was scrapped in 1953.
Combat history.
Winter War.
On 7 December "Iku-Turso" was sortied to intercept the Soviet freighter "Ivan Papanin" sailing from Stockholm. The submarine was informed of the departure time of the target and the likely route and so "Iku-Turso" patrolled in the international waters off Sandhamn and Svenska Högarne during the night. Unidentified patrol boats harassed the submarine and forced it to dive and by the time "Iku-Turso" was able to reach periscope depth there were no freighters in sight. "Ivan Papanin" had passed the area few hours earlier and likely having been warned of the presence of the Finnish submarine, it had altered its course to evade "Iku-Turso".
In late December 1941 "Iku-Turso" patrolled for a couple of days off Liepāja but did not encounter any targets the rules of engagements would have allowed the submarine to attack. In January 1941 "Iku-Turso" patrolled four days off Saaremaa and Hiiumaa but without any luck.
Continuation War.
On 22 June 1941 "Iku-Turso" laid 20 mines north of the island of Mohni/Ekholm. A further 20 mines were laid at Ruuskeri SE from Gogland on 24 June and 18 mines to south of Vaindloo on 26 June after which further minelaying operations were postponed. "Iku-Turso" laid 18 already loaded mines on 11 July of the coast of Estonia east of Mohni.
On 30 July "Iku-Turso" along with "Vetehinen" were sortied to intercept a Soviet convoy moving to and from the besieged base of Hanko. The submarines saw the convoy but were unable to maneuver to attack position.
In December 1941, after the Soviets had evacuated Hanko, "Iku-Turso" was docked for the winter. Though "Iku-Turso" had not had much chance of using its torpedoes, the experiences from other Finnish subs were that the Italian torpedoes used (Finnish designation T/40) were unreliable. During 1942, "Iku-Turso" was upgraded with new 12-hydrophone listening arrays and equipped with a depth charge rack capable of carrying 4 depth charges. The submarine was further modified by streamlining the tower and moving the 20 mm gun up to the tower.
On 27 October 1942, after unsuccessfully attacking a Soviet with the 20 mm Madsen cannon in poor visibility, "Iku-Turso" later came across and torpedoed another Soviet Shchuka-class submarine. After the torpedo impacted, the target disappeared. On the impact site, the Finnish submarine located a large oil spill with even more oil still rising to the surface. The sunken submarine's identity has later been contested as several Soviet submarines of Shchuka class were lost at that time in the area but the most likely candidates are either "Shch-320" or perhaps even more likely "Shch-308" as some Russian sources claim that "Shch-320" had been sunk by a mine earlier that month and that the initial unsuccessful attack by "Iku-Turso" had been against "Shch-307".
On 30 July 1944 "Iku-Turso" attempted to attack a convoy targeting a tug but failed to reach firing position. On 24 August 1944 "Iku-Turso" ran into an obstacle — apparently an anti-submarine net - but was able to get loose. A mine which had been attached to the obstacle exploded but caused only light damage to the submarine.
Notes and references.
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