Pisani-class submarine

The Pisani-class submarines were built for the Regia Marina (Royal Italian Navy) during the late 1920s. They played a minor role in the Spanish Civil War of 1936–1939 supporting the Spanish Nationalists.

Design and description
Designed in parallel with the Mameli-class submarines, the Pisani class was larger to accommodate more fuel and give them more range. They displaced 866 LT surfaced and 1040 LT submerged. The submarines were 68.2 m long, had a beam of 6.09 m and a draft of 4.93 m. They had an operational diving depth of 90 m. Their crew numbered 48 officers and enlisted men.

For surface running, the boats were powered by two 1500 bhp diesel engines, each driving one propeller shaft. When submerged each propeller was driven by a 550 hp electric motor. Like the Mamelis, their stability was poor and they had to be modified with bulges after completion. This reduced their speeds from 17.25 kn on the surface and 8.75 kn underwater to 15 kn and 8.2 kn respectively. On the surface, the Pisani class had a range of 5000 nmi at 8 kn; submerged, they had a range of 70 nmi at 4 kn.

The boats were armed with six 53.3 cm torpedo tubes, four in the bow and two in the stern for which they carried a total of nine torpedoes. They were also armed with a single 102 mm deck gun forward of the conning tower for combat on the surface. Their anti-aircraft armament consisted of two 13.2 mm machine guns.

Service history
During the Spanish Civil War, Vettore Pisani made at least one patrol off the Catalan coast in August 1937 during which she made one unsuccessful attack.