| Page Created |
| January 17th, 2025 |
| Last Updated |
| January 17th, 2025 |
| Italy |
 |
| Length |
| 61.5 metres |
| Wide |
| 5.7 metres |
| Draught |
| 4.7 metres |
| Tonnage |
| 691 |
| Propulsion |
| two diesel engines |
| Armour |
| – |
| Armament |
- four bow 53.3-centimetre torpedo tubes
- two stern 53.3-centimetre torpedo tubes
- 12 torpedoes
- single 100-millimetre deck gun
- four 13.2-millimetre machine guns.
| Sirena-Class Submarine |
 |
The Sirena-class submarines are the second sub-class of the 600 Series coastal submarines constructed for the Regia Marina during the early 1930’s. Of the twelve submarines built in this class, only one survives the Second World War.
The Sirena-class represents an improved and slightly larger design compared to its predecessor, the Argonauta-class. These submarines displace 691 metric tons surfaced and 850 metric tons submerged. They measure 61.5 metres in length, with a beam of 5.7 metres and a draught of 4.7 metres. Each submarine accommodates a crew of 45 officers and enlisted men.
For surface propulsion, the Sirena-class is equipped with two diesel engines, each producing 675 brake horsepower, driving a single propeller shaft. When submerged, propulsion is provided by two electric motors, each generating 400 horsepower. The submarines achieve a maximum surface speed of 14 knots and can reach 7.5 knots when underwater. They have a surface range of 5,000 nautical miles at a cruising speed of 8 knots and an underwater range of 72 nautical miles at 4 knots.
Armament includes six 53.3-centimetre torpedo tubes, with four mounted in the bow and two in the stern, allowing each vessel to carry a total of 12 torpedoes. For surface engagements, the submarines are equipped with a single 100-millimetre deck gun positioned forward of the conning tower. Anti-aircraft defence consists of two to four 13.2-millimetre machine guns.
The Sirena-class embodies advancements in range and firepower compared to earlier designs, making them versatile for both offensive and defensive operations. Despite these capabilities, the class suffers significant losses during World War II, with only one submarine surviving the conflict.
| Submarine Ametista |
The submarine Ametista of the Sirena-Class is the first vessel converted for the transport of Siluri a Lenta Corsa manned torpedoes. In early 1940, the La Spezia Shipyards modify the submarine by installing three deck saddles designed to secure the Siluri a Lenta Corsa’s during transport. Under the command of Lieutenant Junio Valerio Borghese, the Ametista is used to conduct the first experiments in transporting and deploying the craft in the waters off the Ligurian base.
During the final exercise, the Ametista transports three Siluri a Lenta Corsa’s close to boom defences, simulating an attack on the hull of the decommissioned cruiser Quarto, which is moored to a buoy in the roadstead for training purposes. Out of the three devices launched, only one successfully reaches the target and attaches its training head to the hull, demonstrating the concept’s potential but highlighting operational challenges.
Following the completion of these trials, the saddles are removed, and the Ametista is restored to its original operational configuration. The tests, while generally promising, reveal significant limitations. The placement of the Siluri a Lenta Corsa’s on deck saddles exposes the craft to sea conditions that can cause damage during long transits. Additionally, the submarine’s operational depth is restricted to a maximum of 30 metres to ensure the safety of the transported devices, limiting its maneuverability and increasing its vulnerability during extended missions.
Despite these challenges, the Ametista remains an integral part of the early development of Italian manned torpedo operations. Over the course of the war, the submarine completes 27 missions. However, following the armistice in September 8th, 1943, the Ametista is scuttled off Numana near Ancona on September 12th, 1943 to prevent its capture.
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