Marconi-class submarine

The Marconi class was a group of six ocean-going submarines built for the Italian Regia Marina and launched between 1939 and 1940. The boats were built at the Cantieri Riuniti dell'Adriatico yard at Monfalcone, and the Wikipedia infobox also names Odero Terni Orlando among the builders. They had two CRDA diesel engines and two Marelli electric motors, a surfaced speed of about 17.8 knots and a submerged speed of about 8.2 knots, and they carried eight 533 mm torpedo tubes and a 100 mm gun. The class included Leonardo da Vinci, which became the most successful Italian submarine of the Second World War. All of the boats except Luigi Torelli were lost in the Atlantic during the war.