Acciaio class Submersible (1941)

The Acciaio-class submarine were the penultimate class in the 600 Series, first WW2 class, decided and ordered aft Junbe 1941 and the Regia Marina already at war. They were still semi-coastal submarines wth solid range, good armament, same basic design as their predecessors. They returned to names based on minerals, and built by OTO, Muggiano, CRDA, Monfalcone and Tosi in Taranto shipyards in 1940-42. They were relatively successful, and also paid a heavy price in operations, with eight out of thirteen lost in action, others due to scuttling in 1943 and just four surviving World War II. They took part in all important operations.

Development

The Acciaio-class submarine were near-repeats of the preceding Adua, themselves derived from the Perla, Sirena and Argonauta class, of the “Bernardis” single hull designs, with blisters and minor upgrades. They were all named after metals, and ordered in June 1940, as Italy entered the war, from Odero Terni Orlando (OTO), Muggiano, Cantieri Riuniti dell’ Adriatico (CRDA), Monfalcone and Tosi in Taranto, the “usual suspects”. The admiralty wanted more speed, and when Tosi proposed more powerful engines, it was decided it was worth the loss of the two stern torpedo tubes, giving a surface speed of 14.7 knots (27.2 km/h; 16.9 mph), buy only on, the Tosi built boats, Argento, Bronzo and Volframio.

The conning tower “bridge” was brand new and the most distinguishing aspect of the class. It was no longer the classic streamlined, fully enclosed shape of the past, designed for less resistance underwater, but in the “German style”. Meaning it had an open station forward, the helmsman post was deleted (which also simplified construction), albeit voice tubes in the CT enabled rapid orders to be passed on to the helsman below. The aft part was enclosed by a simple guard barrier with pintles for Breda AA HMGs. Otherwise other details of the hull were similar to pas designs.

Like the previous boats they also had radiogoniometer controllable from inside. They however missed the air conditioning system of the Adua, designed for African service, and that proved a blessing given their issues (causing the loss of Macallé notably). Displacement rose a bit, fuel stowage as well. As this last, 5th series of 600t submarines, and a repetition of Adua class the smaller (but taller anf offering more vibility) German style CT improved stability. Diesels were made more poerful as well. In Italian nomenclature they were “medium” types.

About the names: In Italian sources they were often referred as the “Platino” series as the class or “Metalli”. It was not the first time material names (see the “gems” before or part of the Adua batches) were used for submarines but it was unique to the Regia Marina. Being the most recent Italian submarines in a large homogeneous class, they saw plenty of action and met successes, but also paid dearly their wartime operations.

Design of the Acciaio/Platino class

Hull and general design

src assoc. navimodellisti bolognesi via betasom.it

The Acciaio class had a designed surfaced displacement of 697 long tons (708 t) surfaced and 850 long tons (864 t) submerged versus 680/844 metric tons submerged on the Adua, a small, but not insignificant increase. To be exact this varied between builders from 629 to 643 tonnes normal and 697 to 850 tonnes submerged and submerged, fully loaded. The size was the same, with an overall length of 60.18 m (197 ft 5 in) in overall length, a beam of 6.44 m (21 ft 2 in) and draft of 4.78 m (15 ft 8 in), only figures that cghanged compared to the Adua class.

The crew comprised 45 men, 41 ratings and 4 officers. The hull was virtually identical to the Adua, sporting the very same “shark bow” for better seaworthiness, a raised deck, same outer hull lines in the prolongation of the 600 series, same overall design for water scoops over the ballasts, a few ones in the bow and two-rows series. The conning tower design as said above was the greatest difference and easiest recoignition point. Instead of the traditional, enclosed helsman’s post forward, open spotting bridge behind around the central cone of the CT housing the two periscope tubes, it was designed in the “German style”, with an open bridge forward, protected from waves by two breakers, one mid-height at the level of the aft platform and another at the rim of the bridge’s bulwark.

This space contained all the bells and whistles of an open bridge less the Helsman’s post, with voice pipes down. There was a step at its base also, housing ammunitions for the deck gun. Let’s recall here that this design was about the same size and tonnage as the German Type VIIa. So both CTs were quite similar. We don’t know however if German engineers came in Italy or the contrary to design these, but they still diverged in details; The position and shapes of the recesses for the lights for example, the shape of the bell, the portico supporitng protective steel cables, the shorter aft platform but taller structure overall, this was all Italian. In the end, it cause slightly less drag and reduced top weight, improving stability, and aside being a better lookout position, that was the main idea behind this design change. There were slight changes in shape also between yards. Acciaio fo example had the aft bulwark cut to free the platform, whereas CRDA, Monfalcone might have a fully enclosed aft sail. The CT changed when rebuilt for the Marina Militare in the cold war as well (see below).

The hull was pretty much the same as before, with marked blisters over the outer hull, two anchors in recesses forward, main upwards folding diving planes, aft exhausts, rear propellers protected by side framing and upper anti-collision bars on the upper stern hull. Propellers were also protected from grounding by a lower extension bar acting as underkeel for the main axial rudder as well, connected on its axis. The deck also had wwo main hatches paced the same as before (also the same accomodations, including those for the new air conditioning system), the largest one was located aft, acting with a submersion chamber for evacuations. Another was located in the CT.

The pressure hull was separated into 6 main compartments. Forward to aft, the forward torpedo room integrated the four tubes, going through the hemispheric cap ending the pressure hull’s head, narrow, and berthing for the forward crew, then a flat bulkhead and forward escape hatch, forward living quarters, mess and galley, the CO compartment separated by concave walls, aft crew quarters. Aft, was the engine compartment for the diesels, one for electric engines with a light separation, in the last aft compartment (flat bulkheads) and the aft torpedo room and extra berthing, ending in a needle-like fashion with the same convexe cap though which went the two aft tubes.

On the surface, the hull sported the same usual net-cutting saw at the nose, with extra cutting tooth on the chin, deck struts to support the wireless radio cables, anchored on two T style masts fore and aft, then a portico in the CT. The radiogonometric antenna was located either aft or forward of the CT, but this varied by shipyard. They were a few variations in CT shape as said above. A frame could be installed to stretch a tarpaulin for summer navigation, even an extra small spotting platorm aft of the two periscopes. It’s possible that some had their conning tower partly rebuilt in 1942.

Powerplant

The Acciaio class were designed originally to be powered by two Fiat diesels and two CRDA electric motors, albeit Argento, Bronzo, Volframio from Tosi Yard in taranto had their own Tosi diesels and two Ansaldo or Marelli electric motors. Whatever the case, requirements were strict and they were supposed to all be rated for 1,400 hp (1,000 kW) or 700 bhp each, and the electric motors to be rated at 800 bhp (600 kW) and 400-horsepower (298 kW) each.

The previous Perla and Adua indeed had 600-brake-horsepower (447 kW) diesels instead. What did not changed were the mass-produced 3-bladed bronze fixed pitch propellers and the electric motors. Argento, Bronzo, Volframio had better Tosi diesels rated for 750 hp each, for 1500 hp total, but these long diesels, receiving extra cylinders, forced the adoption of a longer machinery space, which in turn pushed the following electric engine space futher aft. This left too little space for a practical aft torpedo room, so it was deleted pure and simple. Conversely this freed a lot of space there for extra berthing or payloads, provided they did not changed the weight balance.

These submarines could reach in any cases 14 knots (26 km/h; 16 mph) surfaced but a bit more, 7.7 knots (14.3 km/h; 8.9 mph) underwater than the previous Adua. The three Tosi boats could reach 14.7 knots surfaced, a 0.7 knots improvement for the lost of their aft torpedo tubes. While surfaced, the Aciaio or Platino had a range of 3,180 nmi (5,890 km) at 10.5 kn (19.4 km/h) surfaced, the same noted for the Adua class, so no improvement there, based on 78 tonnes of diesel oil. Other sources points out 2,300 nautical miles (4,230 km) at 14 knots, so close to full speed. When submerged, this range fell to 80 nmi (148 km; 92 mi) at 4 knots (7.4 km/h; 4.6 mph), still an improvement over the previous class (78 nm), due to a revised battery with more modern cells.

Armament of the Acciaio class

It was the same as the Perla and Adua class: One deck gun, the usual 100mm/47 M1935 on deck, two 13.2 mm Breda M.1931 in thre CT, six 533mm or 21 inches torpedo tubes, four in the bow, two in the stern, apart for the Tosi boats as seen above.

Cannone da 100/47 Mod. 1938

Placed on the forward deck, on wider platform well integrated into the hull, and raised to act as an extra wave breaker to avoid sea spray. This 100 mm/47 (3.9″) Modello 1938 benefited from developments and improvements made on the earlier Modello 1935, manufactured by OTO. It’s possible that some were completed with the Modello 1935 if the 1938 was not available. They carried either 144 or 152 rounds. There were aletrnatives though: Instead of two single 13.2 mm HMGs, some boats could have two twin mounts instead or a single 20mm/70 Scotti-Isotta Fraschini Modello 1939 AA gun, or two of the same.

Specs

Gun Length oa: 194.5 in (4.940 m), 8-10 rpm.
Fixed Ammunition (HE) 30.4 lbs. (13.8 kg) 2,756 fps (840 mps)
Range: 35° 13,800 yards (12,600 m), OTO 1932
Weight 4.6 tons (4.7 mt) -5 /+32 or 35°.

AA: Breda Breda Mod. 31

The anti-aircraft defence counted on one or two twin Breda M1931 13.2 mm L/76 heavy machine guns, placed aft of the conning tower. Each mount weighed 695 kg, but ensured an elevation of -10° to 90°. They fired 125 g unitary rounds, with a muzzle velocity of 790 m/s, maximum range of 6,000 meters and effective range of 2,000 meters. Their rate of fire was 500 rounds/min, so 2,000 rounds when both twin mounts fired in concert, however. They carried a total of 3,000 rounds. It seems before or during the war, this progressed to two twin mounts for extra AA firepower according to many sources.

20mm/70 Scotti-Isotta Fraschini Modello 1939

In alternative, some boats could received either one or two of the latter. The Scotti-Isotta Fraschini Modello 1939 instead of the Breda 20 mm, experiencing bottlenecks. Development started in 1930 through a collaboration between designer Alfredo Scotti an Officine Meccaniche A. Grandi, to create a versatile anti-tank and anti-aircraft gun. It had a gas-operated automatic mechanism, fixed barrel, gas-actuated breech-locking system patented by Scotti in 1931. The first was chambered for a 20x110mm cartridge for 15-round box magazines or 60-round drum magazines with gravity feed, single-barrel or twin-barrel static mount. Tested in 1932 it lost in competition in 1935 againsty the Breda 20/65 Mod. 1935 chambered for the better 20x138B cartridge. However, manufacturing rights were licensed to Isotta-Fraschini which continued development for a new ground-based version chambered for 20x110mm until 1937 and then the 20x138B cartridge with identical feed clips as the Breda Mod. 35.

At last it met success, with production orders from the Regia Aeronautica and Regia Marina as the “Scotti-I.F based on the 20/70 Mod. 38”. It was compatible with a wide variety of mounts.
It was followed by the Scotti-I.F. Mod. 39 (adopted here) featuring a dual gas-regulation valve and made under licence by C.E.M.S.A as the Scotti-O.M. Mod. 41 for the Royal Army. Thos of the Navy had the same types of mounts. After 1943 the Wehrmacht used them as the 2 cm Scotti (i). It was also adopted by the Dutch Army and in 1938, by Nationalist Spain. The British also captured some. Itw as dubbed the “Italian Oerlikon” but apart its 70 calibre, the two were not related.

Specs

Mass 70.5 kg, length 2,270 mm, barrel 1,400 mm, rifling 8 grooves, right-hand twist.
Caliber 20 mm for 20 × 138 mm B rounds 136 g (330 g full), rate 230 rounds/min
Muzzle velocity 830 m/s
Best Range 5,500 m
Feed system Production models: clip-fed.
Elevation -10°/+85°, Air-cooled

12x 533 mm (21 inches) torpedoes

The Acciaio/Platino class submarines repeated the previous class for the stabndardized torpedo armament, six overall including four in the bow, and two in the stern, all reloadable for the pressure hull, and a reserve of 10-12 torpedoes including the six already in the tubes. The three Argento group (Tosi) had only four in the bow, for 8 torpedoes total.
Models available in 1936:
-W 270/533.4 x 7.2 Veloce: 1,700 kg, 7.2 m WH 270 kg, 3,000-4,000 m/50 knots or 12,000 m/30 knots.
-W 270/533.4 x 7.2 “F”: 1,550 kg, 6.500 m, WH 250 kg, speed 3,000 m/43 knots or 10,000 m/28 knots
-W 250/533.4 x 6.5: 1,550 kg, 7.200 m, WH 270 kg, 4,000 m/48 knots or 12,000 m/30 knots.
-Si 270/533.4 x 7.2 “I”: 1,700 kg, 7.2 m, WH 270 kg, speed 3 km/42 kts or 7 km/32 kts, 9,2km/30 knots, 12km/26 kts
-W 250/533.4 x 6.72: 7.2m, WH 270 kg speed 4km/49 kts or 8km/38 kts.
-Si 270/533.4 x 7.2 “M”: 1,7 ton, 7.2 m, WH 270 kg speed 4km/46 kts, 8km/35 kts or 12km/29 kts.
They were also given also a pair of hydrophones.

---

⚙ specifications as built
Displacement	697 tonnes surfaced, 850 tonnes submerged
Dimensions	197 ft 6 in x 21 ft x 15 ft 8 in (60.2 x 6.4 x 4.78 m)
Propulsion	2 shaft diesel 1,400 bhp, 2 EM 800 hp
Propulsion Tosi boats	2 shaft diesel 1,500 bhp
Speed	14 kts (26 kph; 16 mph) surfaced, 7.7 kts (14.3 kph; 8.9 mph) submerged
Speed Tosi Boats	14.7 kts (27.2 kph; 16.9 mph) surfaced
Range	3,200 nmi at 10.5 kts surf., 80 nmi (148 km; 92 mi) at 4 kts sub.
Max depth	80 m (260 ft)
Armament*	1x 100mm deck gun, 6(4)x 533mm TTs, 2-4x 13.2mmm AA, 20mm/70 Scotti, see notes
Crew	45

Appearance and Camouflage

By default of a reconstruction as they already had the “right CT” at launch, the “metalli” only had little changes, but the possible replacement of their Breda 13.2 mm HMGs in single mounts for twin mounts, or the installation or a 20mm Isotta-Ftaschini Scotti in a single or a twon mount depending on the size of theior open aft platform. As for their liveries, they showed at first the usual 1940 “Grigio Generino Chiaro” and if some showed a standard dark hull paint, the majority had the usual copper-base green (made of acetoarceniate of copper), whereas the upper hull surfaces were all painted with the usual light grey/dark grey combo.

Vertical surfaces had the “Grigio Piombo Ponte”, basically ‘lead grey’. The light grey showed a bluish hue under the Mediterranean light, but it was soon superseded by the “Grigio-Azzuro Chiaro” which mixed light blue to the grey and matched better the sky’s color. During the war they were almost all camouflaged, with a variety of style. It could be a spotted camo in some cases with the military “Verde Scuro” or a mix between it and the Grigio Plombo, darker in tone. But straight shapes, triangles or large areas paintd in dark grey, same Grigio Piombo Ponte, was the norm.

Postwar Service: Giada

The only one to survive in good shape the war, was Giada. In 1953 she lost her 100mm/47 gun and her fin was streamlined, she kept however two twin 13.2mm/76 of AA defence. As completed after ovehaul she displaced between 701 and 865 tonnes standard and 1,350 and 800hp, for a top speed of 14.7 kts surfaced and 7.9 kts underwater for a crew of 54, and an endurance, surfaced, of 3,500 nautical miles at 8 knots, and she carried 40t of diesel oil, having in addition a radar and sonar. However the AA guns were later removed as an obsolete feature. Guada remained active as a school submarine after Italy joined NATO in 1951 and was decommissioned in 1966 and scrapped.

Career of the Acciaio class

Note, due to the lack of time, these are abbreviated careers with strong points, to be updated in the future.

Built in the Odero Terni Orlando shipyard in La Spezia, she entered service on 30 November 1941. On 10 December 1942 she unsuccessfully attacked a Leander-class cruiser off Algiers. On 7 February 1943, she launched two torpedoes at a ship identified as a Jervis-class destroyer. In reality it was the anti-submarine fishing vessel HMS Tervani with a displacement of 409 tons, which quickly sank with only two survivors. Other sources credit the sinking to her sister ship Platino, stating she was to be instead the fast minelayer HMS Abdiel, missed by two torpedoes in that area and at that time. On 13 July 1943 Acciaio was torpedoed by the submarine HMS Unruly and sank north of the Strait of Messina. Commander t.v. Mario Pescatore and the entire crew went down under.

Built at CRDA Monfalcone, Alabaster entered service on 9 February 1942. She set sail from Cagliari on 13 September 1942 for her first combat mission, under CO t.v. Giuseppe Bonadies, only to be sunk the next day north of Bougie, at 4.20 pm, by an aircraft from the 202nd Wing of the Royal Air Force. The entire crew went down after a direct hit broke her hull.

Argento (Silver) was built at the Franco Tosi shipyard in Taranto, she entered service in September 1941. Her first mission saw her attacked by an aircraft, and managing to shoot it down. In November 1942 she attempted to penetrate the Philippeville harbor as part of Operation Totch counter-attack, without succeeding as patrols were just too strong. On 21-22 January 1943, she was attacked by two aircraft, damaged one enough for it to withdraw and shot down the other. On 21 July she barely dodged torpedoes from an unknown submarine. On August 3 under command of CO t.v. Leo Masina, she was chased off, hit with depth charges dropped by USS Buck off the coast of Pantelleria. Forced to surface, she was scuttled and the crew evacuated. Apart the 6 men killed in the DC hit, all the crew survived and was made POW by USS Buck.

Built at CRDA Monfalcone, she entered service in the spring of 1942. She carried out two attacks, on 14 July and 13 November 1942, but missed (explosion noted in the first case). In the second case she was attacked by an aircraft, repelled, after damaging it. On 17 February 1943 she attacked but missed the destroyers HMS Westland and Easton and was depht charged for seven hours until she was forced to surface, badly damaged, and sank about 25 miles from Bougie. CO Dante Moroni and part of the crew were rescued and captured. 5 men lost their lives however.

Avorio (“Ivory”) was built at CRDA Monfalcone. In wartime, she took part in the air-naval “battle of Mid-August” (Operation Pedestal). On 9 February 1943 she was attacked by the corvette HMCS Regina and hit by depth charges, forced to surface. Ivorio attempted to fight the Corvette with her own deck gun and AA HMGs, but the Corvette was ready and hit straight away te CT, killing the commander t.v. Leone Fiorentini, XO (second in command) and NO (navigation officer). Survivors prepared scuttling charges and started to evacuate when greeted by a boarding party from the corvette, intended to capture her maneuvers. The Canadians however were too late to stop the flooding. All evacuated and “Ivory” sank with 20 men out of 46 still trapped inside.

Built at Franco Tosi shipyard, Taranto, “Bronze” entered service on 21 January 1942. On 13 June 1942, she took part in the “mid-June battle” (Operation Vigorous) when attacked by an RAF patorl aircraft and forced to dive, later surfaced emerged unscathed. Three days later she had the battleship Malaya and an aircraft carrier in her scope, but could not close, located and repelled by the escort. She took part in Operation Pedestal afterwards and on 12 August 1942, torpedoed the large 16,688 GRT steamship Empire Hope, already damaged by air attacks. Six days later, she was attacked by another submarine, and managed to dodge the torpedoes. On 10 December, she launched four torpedoes against two cruisers and destroyers, missed, but the latter followed the trails and started an unrelentless hunt for hourse. She had no damage.

Her crew distinctly during the attack heard after a torpedo launching a detonation and a violent explosion was heard. She rapidly came to the surface, to spot a cloud of smoke at a distance, but no damage was ever confirmed. On 12 July 1943, while off Syracuse, she was attacked by the minesweepers HMS Seaham, Cromarty, Boston and Poole. Hit by depth charges, she was forced to surface and immediately machine gunned. The commander t.v. Antonio Gherardi, second in command and 6 sailors were jkilled on the CT and deck and she was soon boarded and captured, towed to Syracuse for examination. Once done, she was renamed P.714. Transferred to France in 1944, she was renamed Narval and became a sub school in Toulon until scrapped in 1948.

Built at Odero Terni Orlando shipyard, La Spezia, she entered service on October 30, 1941 and took part in Op. Pedestal on August 12, 1942, during which she was at the head of the force that attacked the British convoy. However, while approaching, surfaced, she was spotted by the destroyer HMS Ithuriel. As she dived, Cobalto was hit by depth charges. Severe damage resulted in having her aft compartments flooding, so Lieutenant Commander Raffaele Amilcarelli attempted to surface to save his crew. But as she had done so, Cobalto was immediately hit by gunfire and then rammed by Ithuriel. Her crew surrendered, a boarding party sent in, seizing documents, and the captain attempted to tow Cobalto but she sank. Apart two men killed in action, Sub-Lieutenant Giovanni Gardella and Sailor Mario Volpe, the crew was rescued and made POW by Ithuriel.

Built at CRDA shipyard Monfalcone, Giada entered service on December 6, 1941 and on June 14, 1942, at Operation Vigorous, she spotted the British aircraft carrier HMS Eagle and 17 other ships, and attacked them with four torpedoes. Two explosions were heard (never confirmed). It’s likely they exploded prematurely. In Operaiton pedestal, she failed to reach the British convoy due to an attack by two aircraft, forcing her to manoeuver to dodge bombs. She shot down the second Short Sunderland, not a small feat, but was forced to seek refuge in Valencia for repairs. She was forced to leave duz to neutrality rules and resumed patrols. On January 22, 1943, she fired four torpedoes at a merchant ship escorted by two destroyers. Three explosions were heard and a periscope observation showing the two destroyers assisting thes tricken ship. But was never confirmed.

With the armistice, she surrendered to the Allies at Bône, French North Adrica. The 1947 peace treaty allocated her to France, but France waived its right to take delivery so Giada and Vortice, another also allocated to France were granted back to Italy. They were not sold for scrap as they were retained as generator hulks during the reconstruction of Italy. Giada was now called V. 1. However, they were secretly used for training at night (Italy was prohibited by treaty to have submarines, like Germany). But in 1951, when Italy entered NATO, this was lifted and and Giada (like Vortice officially were recommissioned under their original name. Modernized in 1952–1953 Giada was decommissioned in 1966 and scrapped.

Granito (‘Granite’) was built at CRDA Monfalcone, entering service on January 3, 1942. On August 14, she launched all torpedoes but missed any targets. On November 14, 1942, while sailing from Augusta toward her patrol area, she was caught by HMS Saracen underway surfaced by night, and struck by three torpedoes, breaking and sinking immediately with all hands.

Nichelio (“Nickel”) was ordered from Odero Terni Orlando shipyard, La Spezia, entering service on July 30, 1942. On January 17, 1943, she was surfaced underway when attacked by an aircraft, but repelled it by gunfire. On July 14 she was attacked by night, by motor torpedo boats south of the Strait of Messina, returned fire with her deck gun, sinking MGB 641 and repelling the others. On the afternoon of the 19th, Nichelio spotted a steamer, estimated 8,000 GRT, escorted by two corvettes. She fired two torpedoes, albeit one was stuck in the tube. She reported a hit and the merchant ship starting to settle by the stern, apparently sinking but she ship survived, only damaged. After the armistice, she surrendered to the Allies at Bona and was agreed to remained in service with the Free Italian Navy, training allied crews as part of the co-belligerence. After peace treaty, she was handed over to the Soviet Union on February 7, 1949 and redesignated Z. 14, remaining in service there until 1960 and scrapped.

Built at Odero Terni Orlando shipyard, La Spezia, she entered service on October 2, 1941. On March 17, 1942, she was attack while surfaced by a Bristol Blenheim. Three bombs fell but missed. Her AA managed to damage and repel the bomber. On November 13, under command of Lieutenant Roberto Rigoli she managed to enter the roadstead of Bougie, torpedoed the 16,642-gross-ton steamer Narkunda. Due to shallow water, the latter remained partially above the surface. She was however finished off by German bombers the following day. During the night of January 29, 1943, under command of Lieutenant Vittorio Patrelli Campagnano, she fired four torpedoes at a convoy off Cape Carbon. The corvette HMS Samphire was hit and sank, albeit postwar records attribute her instead the sinking of the anti-submarine trawler HMS Tervani on February 7, 1943 rather than Acciaio*. On February 18, she attacked another convoy of ten merchant vessels, firing four torpedoes, heard a detonation but nothing was confirmed. With the armistice, she surrendered to the Allies at Bône. In the co-belligerence she performed five missions and in 1948, was stricken and sold for BU in accordance with the peace treaty.

Laid down on November 9, 1940 at CRDA Monfalcone, Porfido was launched on August 23, 1941, and entered service on January 24, 1942. She was present for Operation pedestal, and made a total of five combat patrols. On December 2, 1942, she departed for her final mission off Bône. At 01:50 on December 6, she spotted the british T-class large sub. HMS Tigris, which also had spotted her and alreayd fired in between two torpedoes: One missed, the other struck Porfido in her engine room. She sank in twenty seconds near La Galite Island with just 4 survivors rescued by Tigris.

Built at Franco Tosi shipyard, Taranto, she started her first mission on August 7, 1942, for Operation Pedestal. Afterwards she was selected to transport commando units, but all these spec ops missions failed: On February 2-8, 1943, Allied air and naval opposition was too strong. On a third attempt on May 30, she had to turn back due to bad weather. When the armistice came out she was under repairs in La Spezia; unable to move, she was scuttled in the harbor workers on September 9. Salvaged by the Germans, she was examined, never repairs and sunk again during an air raid in 1944, raised and scrapped postwar.

Read More/Src

Books

Bagnasco, Erminio (1977). Submarines of World War Two. Annapolis, Maryland: Naval Institute Press.
Chesneau, Roger, ed. (1980). Conway’s All the World’s Fighting Ships 1922–1946. Greenwich, UK: Conway Maritime Press.

Frank, Willard C. Jr. (1989). “Question 12/88”. Warship International. XXVI (1): 95–97.
Giorgerini, Giorgio (2002). Uomini sul fondo. Storia del sommergibilismo italiano dalle origini ad oggi (Second ed.). Mondadori.
Pollina, Paolo (1963). I Sommergibili Italiani 1895–1962. Rome, Italy: SMM.
Rohwer, Jürgen (2005). Chronology of the War at Sea 1939–1945: The Naval History of World War Two (Third Revised ed.). NIP.

Links

uboat.net
betasom.it scirè

sommergibili.com
sommergibili.com
navypedia acciaio class
commons.wikimedia.org
it.wikipedia.org
en.wikipedia.org
xmasgrupsom.com

Model kits

None found