| Page Created |
| January 17th, 2025 |
| Last Updated |
| January 17th, 2025 |
| Italy |
 |
| Length |
| 63.15 metres |
| Wide |
| 6.98 metres |
| Draught |
| 4.87 m |
| Tonnage |
| 930 |
| Propulsion |
| 2 Diesel engines, 2 Electric motors |
| Armour |
| – |
| Armament |
- four bow 53.3 centimetre torpedo tubes
- two stern 53.3 centimetre torpedo tubes
- 12 torpedoes
- single 100-millimetre/47 caliber Deck gun
- 4 13.2-millimetre anti-aircraft guns
| Flutto-Class Submarine |
 |
The Flutto-class submarines are a significant development of medium-sized, or seagoing, submarines designed for the Regia Marina. Based on the 600 Series, these submarines are built using a partial double-hulled Bernardis design, incorporating lessons learned from wartime experience. The design prioritises mass production, improved seaworthiness, stronger hulls, better internal arrangements, enhanced anti-aircraft defences, and faster diving times. The Flutto-class is considered the most advanced medium-displacement submarine series constructed by Italy during the war.
A total of 48 submarines are ordered, divided into three series, or Types. The first series (Type I) features names inspired by marine terms and sea creatures, while the second (Type II) and third (Type III) series bear names of metals. The class takes its name from the Italian word Flutto, meaning wave.
The first series comprises 12 submarines laid down in 1941, with six built by CRDA, three by OTO, and three by Tosi. Of these, 10 are completed and see service, while two remain unfinished at the time of Italy’s armistice in September 1943, with construction abandoned thereafter. Of the operational vessels, three are sunk by Allied forces during the war, while four are scuttled by their crews during the armistice to prevent capture. These scuttled submarines are later raised by the Germans, refitted, and redeployed, but all four are subsequently destroyed in Allied air raids in 1944.
The remaining three Type I submarines, including Grongo and Murena, are surrendered to the Allies and survive the war. Grongo and Murena are modified with containers for carrying Siluro a Lenta Corsa, enabling them to support special operations conducted by the Xa Flottiglia MAS.
The second series consists of 24 submarines, laid down in 1942. This series introduces minor design modifications, including a slightly enlarged hull to address trim issues encountered in the Type I vessels. These submarines are distributed among three builders: 15 at CRDA, six at OTO, and three at Tosi. However, Italy’s armistice in September 1943 halts construction on all vessels, and none are completed at the time. Many incomplete hulls fall into German hands, and work continues on some of these submarines, but none become operational before Germany’s surrender in 1945.
The third series is planned as a copy of the Type II design, with construction scheduled to begin in 1943. However, none of the submarines in this series are laid down before Italy’s surrender in September 1943, and the entire series is subsequently cancelled.
| Xa Flottiglia MAS |
The Murena, Sparide, and Grongo are the three submarines of the Flutto-Class constructed at the OTO shipyard in Muggiano, La Spezia. They are launched on April 11th, 1943, February 21st, 1943, and May 6th, 1943, respectively. During outfitting, Sparide and Grongo are assigned to the Xa Flottiglia MAS for assault craft transport roles, while Murena is already fitted with watertight cylinders at the time of its launch.
Unlike earlier conversions, these submarines feature four watertight cylinders instead of three. The cylinders are mounted above the ballast tanks on either side of the conning tower, rather than forward and aft of it. This configuration improves their capacity for carrying explosive motorboats or other assault craft.
Murena is scheduled to carry out its first operational mission in early October 1943 under the command of Lieutenant Commander Luigi Longanesi-Cattani. The mission involves transporting four Motoscafo Turismo Ridotto explosive motorboats in its cylinders to target Gibraltar. However, the submarine remains in La Spezia when the Italian armistice is declared. Despite being operationally under the control of Xa Flottiglia MAS, inaccurate information regarding its status leads the local Navy Department to order its scuttling, which is carried out along with Sparide, the latter being unable to move under its own power.
Grongo, still under construction at the time, is sabotaged to prevent its immediate use but is later captured by German forces. The Germans refloat Murena and Sparide alongside Grongo, renaming them U.It. 16, U.It. 15, and U.It. 20, respectively. Plans had been made to assign at least one of these submarines, likely Murena, to the Republican Xa Flottiglia MAS for assault craft transport following the completion of restoration work. The submarines are towed to Genoa for further outfitting but are destroyed during Allied aerial bombardments in September 1944.
| Multimedia |
