The German siege of Leningrad was broken at Pähkinälinna in January. Soviet troops opened a land route along the coast of Lake Ladoga to besieged Leningrad and thereafter the supply route by lake was no more important. Finland began to seek a way out of the war after the disastrous German defeat in Stalingrad January-February 1943. Negotiations were conducted intermittently between Finland on the one side and the Western Allies and the Soviet Union on the other, but no agreement was reached.
|The Navy had now five detachments and one submarine flotilla. It was still organized partly under command of Commander of the Navy and partly under direct command of Commander of the Naval Forces. Commander of the Navy was in charge of naval operations in the Gulf of Finland. The bulk of the Navy was divided in to four Detachments.
The year 1943 was still trench warfare also on the sea front. Winter had been mild and the Gulf of Finland was free from ice in March. The Soviet submarines had broken through the mine barrages in the Gulf of Finland too easily in previous year. To keep Soviet submarine force away from Baltic shipping stronger efforts were planned. The barrages would be larger and in addition a double submarine net would be laid from Porkkala to Naissaari, operation "Walross".
|Repair of the "Nashorn" mine barrage began on 24.4. and it continued till the end of June. The barrage had more than 8 400 mines of which 838 were bottom mines against submarines. The "Rukajärvi" and "Seeigel" fields were also improved and they consisted of more that 10 000 mines.|
|The submarine net was 30 miles long, 60 to 90 metres high. It was made from 18 mm steel wire with 4 x 4 m mesh. The netlaying operation began on 28.3.1943 and it was finished on 15.5. The old Russian net on the Finnish coast was replaced 10.6. Because of the net all submarine hunting forces could be concentrated between Porkkala and Suursaari.|
The only unit lost in 1942 had been a motor mine sweeper. Motor torpedo boat strength increased tremendously this season. When in 1942 there had been only four old worn-out Thornycroft boats and two captured vessels, the season 1943 began with three new classes of boats:
With the three captured enemy boats there was now boats for two flotillas. Motor Torpedo Boat Detachment was created, with "Taisto" and "Jymy" classes in first Flotilla and "Hurja" class and captured boats in second Flotilla.
The sailing season 1943 began with setbacks for Finns. Gunboat Turunmaa was hit by bombs and to prevent sinking it was beached in shallow water at Haapasaari islands on 2 May. The boat was raised immediately and repaired, but it was not back in service until end of October. 15.5. old Thornycroft boat Raju hit an underwater boom obstacle and sank. The boat was not repaired anymore. Vinha and repaired Syöksy were transferred to Lake Ladoga as patrol boats. 22.5. patrol boats were in fight with Soviet boats. Two men were lost in VMV 17 and four men wounded.
|The Soviet submarine operation began in May when Щ-class boats sailed. They managed to cross the mine barrages, but not the submarine net. One boat was damaged by mines, one was destroyed by Finnish light naval units and one disappeared. The larger S-class boats sailed in August. Two boats sailed, neither returned.|
Motor torpedo boats of the 1st Flotilla attacked enemy convoys sailing to Lavansaari. On 19/20. August Taisto 1 and Taisto 5 shot torpedoes against three barges, of which at least one was sunk. The following night Taisto 2 sank a barge and Taisto 6 a transport. In the night 6/7 September 1st Flotilla was hunting near Seiskari. The MTB's managed to sail to south from the convoy after some skirmishes with enemy patrol boats. At 03.03 the flotilla attacked. Taisto 2 and Taisto 6 sank together a 2 000 ton barge and Jymy 3 a smaller one. In the end of summer the second MTB flotilla dropped mines in the areas of Diamant shallows, northeast from Seiskari, northwest and southwest from Lavansaari, the "Salpa" barrages.
When the submarine operation had failed, Soviet forces began to attack German small naval units protecting the mine barrages. Auxiliary gunboat Ost and M 15 were damaged and while retreating Ost hit a mine southwest from Tytärsaari and sank. M 18, M 30 and M 17 had to be taken away from Narva Bay. On 15.9. auxiliary gunboat West was lost south from Neugrund and M 22 had to be towed away from the area. Combined attacks of air force and MTB's forced German units to retreat with heavy losses and from the middle of September nobody was defending "Seeigel". The Baltic Red Fleet managed to sweep a channel through "Seeigel" between Neugrund and Namsi, but this was of no use yet.
The Finnish Navy suffered some heavy losses during the season. Minelayer Riilahti was torpedoed on the night of 24.8. southeast from Tiiskeri. Torpedo from Soviet MTB TK 94 hit the ship that sank in two minutes. 11 survivors were picked up, but the commander, Knight of Mannerheim Cross Osmo Kivilinna died later. On 16.9. a low-flying IL-4 torpedo plane surprised escort vessels Uisko and Tursas north from Keri lighthouse. Uisko was hit with the loss of 18 men, including commander, Lt Sandholm. Only two men survived, cook and steward. The wreck was located by an Estonian search team in 2004 and the bow of the vessel was found to be totally destroyed [Paa08]. The icebreaker and depot ship Sisu was damaged by magnetic mine just off Helsinki between Kytö and Rysäkari.