Italian submarine Luigi Settembrini

The Settembrini class was an improved and enlarged version of the preceding Mameli-class submarines. They displaced 953 metric tons (938 long tons) surfaced and 1,153 metric tons (1,135 long tons) submerged. The submarines were 69.11 meters (226 ft 9 in) long, had a beam of 6.61 meters (21 ft 8 in) and a draft of 4.45 meters (14 ft 7 in).[1] They had an operational diving depth of 80 meters (260 ft).[2] Their crew numbered 56 officers and enlisted men.[1]

For surface running, the boats were powered by two 1,500-brake-horsepower (1,119 kW) diesel engines, each driving one propeller shaft. When submerged each propeller was driven by a 700-horsepower (522 kW) electric motor. They could reach 17.5 knots (32.4 km/h; 20.1 mph) on the surface and 7.7 knots (14.3 km/h; 8.9 mph) underwater.[2] On the surface, the Settembrini class had a range of 6,200 nautical miles (11,500 km; 7,100 mi) at 7.3 knots (13.5 km/h; 8.4 mph);[1] submerged, they had a range of 100 nmi (190 km; 120 mi) at 3 knots (5.6 km/h; 3.5 mph).[2]

The boats were armed with eight 53.3-centimeter (21 in) torpedo tubes, four each in the bow and stern for which they carried a total of 12 torpedoes. They were also armed with a single 102-millimeter (4 in) deck gun forward of the conning tower for combat on the surface. Their anti-aircraft armament consisted of two or four 13.2-millimeter (0.52 in) machine guns.[1][2]

Luigi Settembrini was launched by Cantieri navali Tosi di Taranto at their Taranto shipyard on 28 September 1930 and completed later that year.[1] During the Spanish Civil War she made one patrol in the Eastern Mediterranean during which she attacked the 3,100-gross register ton (GRT) Soviet cargo ship SS Blagoev off the island of Skyros on 1 September 1937. Luigi Settimbrini missed with her first torpedo, but the boat surfaced and fired a warning shot, which caused the freighter's crew to abandon ship. The submarine then fired a pair of torpedoes which sank the Soviet ship.[3]

• Bagnasco, Erminio (1977). Submarines of World War Two. Annapolis, Maryland: Naval Institute Press. ISBN 0-87021-962-6.
• Brescia, Maurizio (2012). Mussolini's Navy: A Reference Guide to the Regina Marina 1930–45. Annapolis, Maryland: Naval Institute Press. ISBN 978-1-59114-544-8.
• Chesneau, Roger, ed. (1980). Conway's All the World's Fighting Ships 1922–1946. Greenwich, UK: Conway Maritime Press. ISBN 0-85177-146-7.
• Frank, Willard C., Jr. (1989). "Question 12/88". Warship International. XXVI (1): 95–97. ISSN 0043-0374.
• Rohwer, Jürgen (2005). Chronology of the War at Sea 1939–1945: The Naval History of World War Two (Third Revised ed.). Annapolis, Maryland: Naval Institute Press. ISBN 1-59114-119-2.