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San Giorgio-class cruiser
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San Giorgio-class cruiser
The San Giorgio class consisted of two armored cruisers built for the Royal Italian Navy (Regia Marina) in the first decade of the 20th century. The second ship, San Marco, was used to evaluate recently invented steam turbines in a large ship and incorporated a number of other technological advances. The ships participated in the Italo-Turkish War of 1911–1912, although San Giorgio was under repair for most of the war. San Marco supported ground forces in Libya with naval gunfire and helped them to occupy towns in Libya and islands in the Dodecanese. During World War I, the ships' activities were limited by the threat of Austro-Hungarian submarines, although they did bombard Durazzo, Albania in 1918.
San Giorgio spent several years in the Far East and Italian Somaliland after the war and became a training ship in 1931. After a brief deployment to Spain in 1936, she was reconstructed to better serve her role as a training ship. The ship's anti-aircraft armament was augmented when she was deployed to Tobruk, Libya to reinforce the port's defenses after Italy declared war on Britain in May 1940. San Giorgio was scuttled in early 1941 when Allied forces were poised to capture the port. Her wreck was salvaged in 1952, but sank while under tow. San Marco was converted into a target ship in the early 1930s and was found sunk at the end of the war. She was scrapped in 1949.
The San Giorgio class was ordered almost immediately after the preceding Pisa-class ships, and was an improved version of that design. The forecastle was extended to improve seaworthiness, turret armor was increased, habitability was improved and the propulsion machinery was redistributed. San Marco was given the first steam turbines fitted in a large Italian ship for comparative purposes with San Giorgio, which retained the traditional vertical triple-expansion steam engines (VTE). San Marco was a very innovative ship as she was the first turbine-powered ship in any navy to have four propeller shafts, the first with a gyroscopic compass, the first with antiroll tanks, and the first not to use wood in any way.
The San Giorgio-class ships had a length between perpendiculars of 131.04 meters (429 ft 11 in) and an overall length of 140.89 meters (462 ft 3 in). They had a beam of 21.03 meters (69 ft 0 in) and a draft of 7.35–7.76 meters (24 ft 1 in – 25 ft 6 in). The ships displaced 10,167–10,969 metric tons (10,006–10,796 long tons) at normal load, and 11,300–11,900 metric tons (11,100–11,700 long tons) at deep load. The ships had a complement of 32 officers and 666 to 673 enlisted men.
The machinery installation of this class was changed in comparison to that of the Pisa class, with the engines amidships with the 14 mixed-firing water-tube boilers fore and aft of the engines. Their exhausts were trunked together into two widely spaced pairs of funnels. Designed for a maximum speed of 23 knots (43 km/h; 26 mph), the two ships were given different types of propulsion machinery for evaluation. San Giorgio's two shafts, pair of 19,500-indicated-horsepower (14,500 kW) VTE steam engines and Blechynden boilers differed only slightly from those used by the Pisas. In contrast, San Marco's four shafts, each driven by a license-built Parsons steam turbine, was a first for the Regia Marina. The turbines used steam provided by Babcock & Wilcox boilers at a working pressure of 210 psi (1,448 kPa; 15 kgf/cm2) to reach their designed output of 23,000 shp (17,000 kW). Both ships exceeded their designed speeds, with San Giorgio reaching 23.2 knots (43.0 km/h; 26.7 mph) and San Marco 23.75 knots (43.99 km/h; 27.33 mph) during their sea trials. The biggest difference between the sisters was that the turbines of San Marco proved to be significantly less economical in service (a range of 4,800 nautical miles (8,900 km; 5,500 mi) at a speed of 10 knots (19 km/h; 12 mph) and 2,480 nautical miles (4,590 km; 2,850 mi) at 21.25 knots (39.36 km/h; 24.45 mph)) compared to San Giorgio's VTE steam engines (6,270 nautical miles (11,610 km; 7,220 mi) at 10 knots (19 km/h; 12 mph) and 2,640 nautical miles (4,890 km; 3,040 mi) at 21.25 knots (39.36 km/h; 24.45 mph).
The main armament of the San Giorgio-class ships consisted of four Cannone da 254/45 A Modello 1907 guns in electrically powered, twin-gun turrets fore and aft of the superstructure. The turrets had an arc of fire of 260°. The 254 mm (10.0 in) gun fired 204.1–226.8-kilogram (450–500 lb) armor-piercing (AP) projectiles at a muzzle velocity of 870 meters per second (2,850 ft/s). At maximum elevation of +25°, the guns had a range of about 25,000 meters (27,000 yd). The ships mounted eight Cannone da 190/45 A Modello 1908 in four electrically powered twin-gun turrets, two in each side amidships, as their secondary armament. Their arc of fire was 160°. These Armstrong Whitworth 190 mm (7.5 in) guns fired 90.9-kilogram (200 lb) AP shells at 864–892 m/s (2,835–2,927 ft/s). At maximum elevation of +25°, the guns had a range of about 22,000 meters (24,000 yd).
For defense against torpedo boats, the San Giorgios mounted 18 quick-firing (QF) 40-caliber 76 mm (3.0 in) guns. Eight of these were mounted in embrasures in the sides of the hull and the rest in the superstructure. The ships were also fitted with a pair of QF 40-caliber 47 mm (1.9 in) guns. The San Giorgio-class ships were equipped with three submerged 450 mm (17.7 in) torpedo tubes. During World War I, eight of the 76 mm guns were replaced by six 76 mm anti-aircraft (AA) guns and one torpedo tube was removed.
The ships were protected by an armored belt that was 200 mm (7.9 in) thick amidships and reduced to 80 mm (3.1 in) at the bow and stern. The belt was 2.2 m (7 ft 3 in) high, of which 1.5 m (4 ft 11 in) was below the waterline. The armored deck was 50 mm (2.0 in) thick and the conning tower armor was 254 mm thick. The 254 mm gun turrets were protected by 200 mm of armour while the 190 mm turrets had 160 mm (6.3 in).
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San Giorgio-class cruiser
The San Giorgio class consisted of two armored cruisers built for the Royal Italian Navy (Regia Marina) in the first decade of the 20th century. The second ship, San Marco, was used to evaluate recently invented steam turbines in a large ship and incorporated a number of other technological advances. The ships participated in the Italo-Turkish War of 1911–1912, although San Giorgio was under repair for most of the war. San Marco supported ground forces in Libya with naval gunfire and helped them to occupy towns in Libya and islands in the Dodecanese. During World War I, the ships' activities were limited by the threat of Austro-Hungarian submarines, although they did bombard Durazzo, Albania in 1918.
San Giorgio spent several years in the Far East and Italian Somaliland after the war and became a training ship in 1931. After a brief deployment to Spain in 1936, she was reconstructed to better serve her role as a training ship. The ship's anti-aircraft armament was augmented when she was deployed to Tobruk, Libya to reinforce the port's defenses after Italy declared war on Britain in May 1940. San Giorgio was scuttled in early 1941 when Allied forces were poised to capture the port. Her wreck was salvaged in 1952, but sank while under tow. San Marco was converted into a target ship in the early 1930s and was found sunk at the end of the war. She was scrapped in 1949.
The San Giorgio class was ordered almost immediately after the preceding Pisa-class ships, and was an improved version of that design. The forecastle was extended to improve seaworthiness, turret armor was increased, habitability was improved and the propulsion machinery was redistributed. San Marco was given the first steam turbines fitted in a large Italian ship for comparative purposes with San Giorgio, which retained the traditional vertical triple-expansion steam engines (VTE). San Marco was a very innovative ship as she was the first turbine-powered ship in any navy to have four propeller shafts, the first with a gyroscopic compass, the first with antiroll tanks, and the first not to use wood in any way.
The San Giorgio-class ships had a length between perpendiculars of 131.04 meters (429 ft 11 in) and an overall length of 140.89 meters (462 ft 3 in). They had a beam of 21.03 meters (69 ft 0 in) and a draft of 7.35–7.76 meters (24 ft 1 in – 25 ft 6 in). The ships displaced 10,167–10,969 metric tons (10,006–10,796 long tons) at normal load, and 11,300–11,900 metric tons (11,100–11,700 long tons) at deep load. The ships had a complement of 32 officers and 666 to 673 enlisted men.
The machinery installation of this class was changed in comparison to that of the Pisa class, with the engines amidships with the 14 mixed-firing water-tube boilers fore and aft of the engines. Their exhausts were trunked together into two widely spaced pairs of funnels. Designed for a maximum speed of 23 knots (43 km/h; 26 mph), the two ships were given different types of propulsion machinery for evaluation. San Giorgio's two shafts, pair of 19,500-indicated-horsepower (14,500 kW) VTE steam engines and Blechynden boilers differed only slightly from those used by the Pisas. In contrast, San Marco's four shafts, each driven by a license-built Parsons steam turbine, was a first for the Regia Marina. The turbines used steam provided by Babcock & Wilcox boilers at a working pressure of 210 psi (1,448 kPa; 15 kgf/cm2) to reach their designed output of 23,000 shp (17,000 kW). Both ships exceeded their designed speeds, with San Giorgio reaching 23.2 knots (43.0 km/h; 26.7 mph) and San Marco 23.75 knots (43.99 km/h; 27.33 mph) during their sea trials. The biggest difference between the sisters was that the turbines of San Marco proved to be significantly less economical in service (a range of 4,800 nautical miles (8,900 km; 5,500 mi) at a speed of 10 knots (19 km/h; 12 mph) and 2,480 nautical miles (4,590 km; 2,850 mi) at 21.25 knots (39.36 km/h; 24.45 mph)) compared to San Giorgio's VTE steam engines (6,270 nautical miles (11,610 km; 7,220 mi) at 10 knots (19 km/h; 12 mph) and 2,640 nautical miles (4,890 km; 3,040 mi) at 21.25 knots (39.36 km/h; 24.45 mph).
The main armament of the San Giorgio-class ships consisted of four Cannone da 254/45 A Modello 1907 guns in electrically powered, twin-gun turrets fore and aft of the superstructure. The turrets had an arc of fire of 260°. The 254 mm (10.0 in) gun fired 204.1–226.8-kilogram (450–500 lb) armor-piercing (AP) projectiles at a muzzle velocity of 870 meters per second (2,850 ft/s). At maximum elevation of +25°, the guns had a range of about 25,000 meters (27,000 yd). The ships mounted eight Cannone da 190/45 A Modello 1908 in four electrically powered twin-gun turrets, two in each side amidships, as their secondary armament. Their arc of fire was 160°. These Armstrong Whitworth 190 mm (7.5 in) guns fired 90.9-kilogram (200 lb) AP shells at 864–892 m/s (2,835–2,927 ft/s). At maximum elevation of +25°, the guns had a range of about 22,000 meters (24,000 yd).
For defense against torpedo boats, the San Giorgios mounted 18 quick-firing (QF) 40-caliber 76 mm (3.0 in) guns. Eight of these were mounted in embrasures in the sides of the hull and the rest in the superstructure. The ships were also fitted with a pair of QF 40-caliber 47 mm (1.9 in) guns. The San Giorgio-class ships were equipped with three submerged 450 mm (17.7 in) torpedo tubes. During World War I, eight of the 76 mm guns were replaced by six 76 mm anti-aircraft (AA) guns and one torpedo tube was removed.
The ships were protected by an armored belt that was 200 mm (7.9 in) thick amidships and reduced to 80 mm (3.1 in) at the bow and stern. The belt was 2.2 m (7 ft 3 in) high, of which 1.5 m (4 ft 11 in) was below the waterline. The armored deck was 50 mm (2.0 in) thick and the conning tower armor was 254 mm thick. The 254 mm gun turrets were protected by 200 mm of armour while the 190 mm turrets had 160 mm (6.3 in).
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