The F class consisted of 27 submarines constructed in the Kingdom of Italy between 1915 and 1918. They were the most numerous class of submarines constructed for the Italian Regia Marina (Royal Navy) during World War I. Twenty-one of them served in the Regia Marina. Three others were sold to Portugal, where they served in the Portuguese Navy as the Foca class. Another three were constructed for Spain, serving in the Spanish Navy as the A class.
== Design == Between 1913 and 1915, the FIAT-San Giorgio shipyard at La Spezia, Italy, built five submarines for Brazil which served in the Brazilian Navy as the F class or Foca class. The Italian Regia Marina (Royal Navy) was quite impressed with the design of the Brazilian submarines and ordered the construction of submarines of an improved design for its own use. In Italy, these also were known as the F class. The F class were small, coastal submarines of the Laurenti type, developed from the earlier Medusa class. Like all Laurenti-type submarines, they had a full double-hull design with an internal pressure hull with variable-section shaping tailoring the hull shape to optimize it for the submarines' machinery, requiring them to have very thick hulls to allow a greater collapse depth. They were agile and maneuverable, optimized for use in enclosed waters like those of the Adriatic Sea. They had radio and a faster diving time than the Brazilian submarines on which their design was based. Unlike the Brazilian submarines, the Italian F class had a deck gun, two periscopes, a gyrocompass, and a Fessenden-type hydrophone and underwater signaling system. Those numbered F13 and higher had their aft diving planes relocated below the waterline and made fixed. Some of the later submarines to enter service had a bridge screen fitted to their conning towers, changing their silhouette significantly. The F-class submarines had a length overall of 45.6 metres (149 ft 7 in), a length between perpendiculars of 45.1 metres (148 ft 0 in), a beam of 4.2 metres (13 ft 9 in), and a draft of 3.1 metres (10 ft 2 in). They displaced 262 long tons (266 t) on the surface and 319 long tons (324 t) submerged. Two Fiat 670 bhp (500 kW) diesel engines driving two screws gave the F-class submarines a top speed on the surface of 12.5 knots (23.2 km/h; 14.4 mph). Their two 500 hp (373 kW) Savigliano electric motors gave them a maximum submerged speed of 8.2 knots (15.2 km/h; 9.4 mph). They could carry 15 tons of diesel fuel, and on the surface they had a range of 1,600 nmi (1,800 mi; 3,000 km) at 8.5 knots (15.7 km/h; 9.8 mph). Submerged, their range was 80 nmi (92 mi; 148 km) at 4 knots (7.4 km/h; 4.6 mph). Each F-class submarine had two 450 mm (17.7-inch) torpedo tubes, both in the bow, and carried four torpedoes. Each submarine also had a 76 mm (3-inch) deck gun. The F-class submarines had a crew of 26, consisting of two officers and 24 enlisted men. They had a diving depth of 45 metres (148 feet).
== Construction == Italian shipyards constructed 21 F-class submarines for Italian service, numbered F1 through F21. FIAT-San Giorgio built 13 of them at La Spezia, while the Cantiere navale fratelli Orlando (Orlando Brothers Shipyard) built five at Livorno (Leghorn) and the Cantieri navali Odero (Odero Shipyards) built three at Sestri Ponente. FIAT-San Giorgio constructed six additional F-class submarines for foreign sale. Three laid down in 1915 and originally numbered F19, F20, and F21 were sold to Portugal while under construction, and they entered service in the Portuguese Navy as the Foca class. Italy replaced them by ordering three additional submarines for the Regia Marina also laid down in 1915 and also numbered F19, F20, and F21, and these were commissioned in the Regia Marina in 1918. Three other submarines FIAT-San Giorgio laid down at La Spezia in 1915 and 1916 were numbered F22, F23, and F24. These were sold to Spain, where they served in the Spanish Navy as the A class.
Submarines of the class
=== Italian F class === SOURCES: F4 sank in an accident in port at La Spezia on 7 July 1917, but was refloated and repaired. F8 sank at La Spezia on 14 February 1917 during her sea trials, but she was refloated, repaired, and in service by September 1917. F14 sank in the Adriatic Sea with the loss of her entire crew in 1928 after colliding with the destroyer Giuseppe Missori during an exercise off Pula, Yugoslavia. She was raised and scrapped.
=== Portuguese Foca class === SOURCES
=== Spanish A class === SOURCES On 28 June 1927, Cosme García sank pierside at Barcelona without loss of life when her torpedo tube doors malfunctioned. She was refloated, repaired, and returned to sevice. After the Second Spanish Republic replaced the Kingdom of Spain in 1931, the three Spanish submarines were part of the Spanish Republican Navy late in their service lives.
References
Citations
=== Bibliography === Chesneau, Roger, ed. (1980). Conway's All the World's Fighting Ships 1922–1946. Greenwich, UK: Conway Maritime Press. ISBN 0-85177-146-7. Gardiner, Robert; Gray, Randal, eds. (1985). Conway's All the World's Fighting Ships 1906–1921. London, UK: Conway Maritime Press. ISBN 978-0851772455. Oliveira, Maurício de (1972). Os Submarinos na Marinha Portuguesa [Submarines in the Portuguese Navy] (in Portuguese). Lisbon: Sociedade Nacional de Tipografia.