The boats were small coastal submarines built to a French design (Loire-Simonet).[1] Ronis means "seal" in the Latvian language, Spīdola is a character from the Latvian language poem Lāčplēsis.[2] The submarines were 55.0 m (180 ft 5 in) long overall with a beam of 4.8 m (15 ft 9 in) and a draught of 3.6 m (11 ft 10 in). The vessels of the class displaced 390 long tons (400 t) surfaced and 514 long tons (522 t) submerged. The submarines had a dived depth of 160 feet (49 m). They had a complement of 27 officers and ratings.[1]
The Ronis-class submarines were propelled by two shafts driven by two Sulzer diesel engines for travel on the surface, rated at 1,300 brake horsepower (970 kW) and two electric motors 700 shaft horsepower (520 kW) for subsurface movement. The submarines had a maximum speed of 14 knots (26 km/h) surfaced and 9 knots (17 km/h) submerged. They were armed with six 21-inch (533 mm) torpedo tubes with two located in the bow, and four situated in two twin external turnable mounts. The Ronis class was also armed with one 75-millimetre (3 in) main deck gun and two 7.62 mm (0.30 in) machine guns.[1]
The two submarines were ordered in 1925 as part of the expansion of the nascent Latvian Navy which was first suggested in 1923.[3] Constructed in France, the submarines were part of the navy's plan to guard Latvia's coastlines. With the onset of the Great Depression, the Latvian Navy comprised just the two submarines and two minesweepers acquired in the 1920s, although Latvia had planned to buy two more submarines of higher tonnage.[3]
Both submarines were sent to Liepāja in 1941 where they were scheduled to overhaul in July. However, with the Germans approaching the city, the Soviets were forced to blow up and scuttle the Ronis-class submarines on 24 June 1941 to prevent their capture.[1] Liepāja was captured on 29 June by the Germans.[4]
Chesneau, Roger, ed. (1980). Conway's All the World's Fighting Ships 1922–1946. Greenwich, UK: Conway Maritime Press. ISBN0-85177-146-7.
Groos, Poul (2017) [2014]. The Naval War in the Baltic 1939–1945. Barnsley, UK: Seaforth Publishing. ISBN978-1-5267-0003-2.
Further reading
Yakubov, Vladimir & Worth, Richard (2008). Raising the Red Banner: The Pictorial History of Stalin's Fleet 1920–1945. Staplehurst: Spellmount. ISBN978-1-86227-450-1.