Perla-class submarine

Perla-class submarine (Perla)
Class overview
Name:	Perla class
Builders:	Odero Terni Orlando (OTO), Muggiano Cantieri Riuniti dell' Adriatico (CRDA), Monfalcone
Operators:	Regia Marina
Preceded by:	Sirena class
Succeeded by:	Adua class
Built:	1935–36
In commission:	1936–1954
Completed:	10
Lost:	6
Scrapped:	4
General characteristics
Type:	Submarine
Displacement:	680 tonnes (669 long tons) surfaced 844 tonnes (831 long tons) submerged
Length:	60.18 m (197 ft 5 in)
Beam:	6.45 m (21 ft 2 in)
Draft:	4.7 m (15 ft 5 in)
Installed power:	1,200 bhp (890 kW) (diesels) 800 hp (600 kW) (electric motors)
Propulsion:	Diesel-electric 2 × diesel engines 2 × electric motors
Speed:	14 knots (26 km/h; 16 mph) surfaced 7.5 knots (13.9 km/h; 8.6 mph) submerged
Range:	5,200 nmi (9,600 km; 6,000 mi) at 8 knots (15 km/h; 9.2 mph) surfaced 74 nmi (137 km; 85 mi) at 4 knots (7.4 km/h; 4.6 mph) submerged
Test depth:	80 m (260 ft)
Complement:	45
Armament:	6 × 533 mm (21 in) torpedo tubes (4 bow, 2 stern) 1 × 100 mm (3.9 in)/47 deck gun 1 or 2 × twin 13.2 mm (0.52 in) anti-aircraft guns

The Perla-class submarines were the third sub-class of the 600 Series of coastal submarines built for the Royal Italian Navy (Regia Marina) during the 1930s. Of the ten boats built of this class, only three survived World War II.

The Perla-class submarines were essentially repeats of the preceding Sirena class. They displaced 680 metric tons (670 long tons) surfaced and 844 metric tons (831 long tons) submerged. The submarines were 60.18 meters (197 ft 5 in) long, had a beam of 6.45 meters (21 ft 2 in) and a draft of 4.7 meters (15 ft 5 in).

For surface running, the boats were powered by two 600-brake-horsepower (447 kW) diesel engines, each driving one propeller shaft. When submerged each propeller was driven by a 400-horsepower (298 kW) electric motor. They could reach 14 knots (26 km/h; 16 mph) on the surface and 7.5 knots (13.9 km/h; 8.6 mph) underwater. On the surface, the Adua class had a range of 5,200 nautical miles (9,600 km; 6,000 mi) at 8 knots (15 km/h; 9.2 mph), submerged, they had a range of 74 nmi (137 km; 85 mi) at 4 knots (7.4 km/h; 4.6 mph).

The boats were armed with six internal 53.3 cm (21.0 in) torpedo tubes, four in the bow and two in the stern. One reload torpedo was carried for each tube, for a total of twelve. They were also armed with one 100 mm (3.9 in) deck gun for combat on the surface. The light anti-aircraft armament consisted of one or two pairs of 13.2 millimeters (0.52 in) machine guns.

Iride and Onice were lent to the Nationalist side in the Spanish Civil War, renamed Gonzales Lopez and Aguilar Tablada respectively. They retained their Italian crews with a Spanish liaison officer. They were returned to the Italian Navy at the end of the conflict.