Brin-class submarine

The "Brin"-class submarine was a group of five long-range submarines built for the Royal Italian Navy ("Regia Marina") during the 1930s.
Design and description.
The "Brin"-class submarines were improved versions of the preceding . 
Two boats were replacements for submarines of that class that were secretly transferred to the Nationalists during the Spanish Civil War in 1937. They displaced surfaced and submerged. The submarines were long, had a beam of and a draft of . The class was partially double hulled.
For surface running, the boats were powered by two diesel engines, each driving one propeller shaft. When submerged each propeller was driven by a electric motor. They could reach on the surface and underwater. On the surface, the "Brin" class had a range of at , submerged, they had a range of at .
The boats were armed with eight internal torpedo tubes, four each in the bow and stern. They carried a total of 14 torpedoes. They were also armed with one deck gun for combat on the surface. The gun was initially mounted in the rear of the conning tower, but this was re-sited on the forward deck later in the war in the surviving boats and the large conning tower was re-built to a smaller design. The light anti-aircraft armament consisted of one or two pairs of machine guns.