Yugoslav submarine Mališan (P-901)

Mališan (pennant number: P-901) was a CB-class midget submarine in service with the Yugoslav Navy (Jugoslavenska ratna mornarica; JRM). Mališan was laid down in 1943 as CB-20 for the Regia Marina. Following the Italian Armistice in September 1943, the unfinished submarine was captured by the Germans who handed it to the forces of the Italian Social Republic. In 1945 the submarine was captured by Yugoslav Partisans in Pula, and soon commissioned with the Yugoslav Navy.

After being decommissioned in the 1950s, the submarine was donated to the Technical Museum in Zagreb. Starting in 2008, Mališan underwent restoration of its interior and exterior which included returning its original Italian paint scheme and designation.

Design and building
Mališan was laid down sometime during 1942 by Caproni in Milan as CB-20 for service in the Regia Marina. The boat measures 15 m in length, with a 3 m beam and a 2.4 m draft. Undewater it displaced 45 t compared to 35.4 t when surfaced. Propulsion consisted of a single 90 hp Isotta Fraschini D 80 diesel engine and a single 100 hp Marelli Motore Corrente Contina MG 754 S electric engine, mounted on a single shaft. Maximum speed was 7.5 kn surfaced and 6 kn when underwater.

Traveling surfaced at a speed of 5 kn the boat had a range of 1000 - 1400 nmi, with the exact figure varying between sources. Traveling underwater at a speed of 3 kn this was reduced to between 50 - 60 nmi. Maximum diving depth was 55 m. The boat's complement during wartime was made of four crew members, one officer and three seamen. During peacetime the boat could have been operated by a crew of just two. Armament consisted of two 450 mm external torpedo tubes located on the sides of the hull.

Service and aftermath
After the Kingdom of Italy surrendered to the Allies on 3 September 1943, the unfinished CB-20 was captured by German forces and completed by March 1944. The boat was then handed over to the forces of the Italian Social Republic as part of the Tenth Flotilla performing reconnaissance and landing saboteurs. Starting from between September and October 1944, CB-20 was homeported in Pula where it was eventually captured by Yugoslav Partisans on 3 May 1945. Renamed Mališan (P-901), translating as nipper in English, the boat was overhauled at the Uljanik Shipyard and commissioned in 1948. The Yugoslav Navy used it for training new submariners as well as evaluating the concept of midget submarines for future use, which eventually materialized in the form of the Una-class midget submarines, three decades later. Depending on source, the exact time Mališan was decommissioned differs from the early 1950s to 1957.

In 1959 the boat was donated to the Technical Museum in Zagreb where it has remained since and is the only known preserved boat of its class. In 2007 the museum decided to perform restoration on the boat which was starting to show signs of degrading condition. Work started in 2008 and included the restoration of the interior. This was followed by work on the exterior in 2009 which returned the boat's original Italian paint scheme and name in favor of its later Yugoslav service.