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REGIA MARINA (ITALY)

CRUISERS

BOLZANO heavy cruiser

Bolzano 1940

Bolzano 1942

Name No Builder Laid down Launched Comp Fate
Bolzano   Ansaldo, Genoa 11/6/1930 31/8/1932 19/8/1933 damaged 13/8/1942, repair incomplete

 

Displacement standard, t

10890

Displacement full, t

13665

Length, m

187.6 pp 196.9 oa

Breadth, m

20.6

Draught, m

6.80 mean deep

No of shafts

4

Machinery

Parsons geared steam turbines, 10 Yarrow-Ansaldo boilers

Power, h. p.

150000

Max speed, kts

36

Fuel, t

oil 2224

Endurance, nm(kts) 4432(16)

Armour, mm

belt: 70, bulkheads: 60 - 50, decks: 50 - 20, barbettes: 70 - 60, turrets: 80, CT: 100 - 40, communication tube: 70 - 60

Armament

4 x 2 - 203/53 Ansaldo 1929, 8 x 2 - 100/47 OTO 1928, 4 x 1 - 40/39 Vickers-Terni 1917, 4 x 2 - 13.2/76, 8 - 533 TT aw (beam, 12), 1 catapult, 3 seaplanes (P.6, M.41, Cant.25)

Complement

725

Ship project history: Bolzano was built under the 1929-1930 program and was the development of Trento class cruisers with increased speed. The hull with obviously expressed forecastle (as on Zara) instead of flush-deck ones, improved machinery, forced to 150000hp, new fore superstructure (as on Pola), new M1929 guns instead of M1924 on Trento became the basic differences.

Though machinery power was raised, the boilers number was shrank from 12 to 10 at the expense of larger steam output of each boiler. The general scheme of machinery arrangement basically repeated accepted on Trento (en echelon), but now the fore group included not 8, but 6 boilers. The second, aft group included, as before, 4 boilers in two rooms, but internal arrangement differed from predecessors. It has been called by necessity to place funnels on larger distance for transference of a catapult from a forecastle (where it was exposed to influence of waves on Trento class) to amidships.

Protection practically did not differ from accepted on Trento.

Bolzano became the fastest Italian "Washington" cruiser: on trials she reached 36.81kts at 173772hp power. Real (during daily service) speed also was appeared enough high: about 33kts.

 13/8/1942 she was damaged by torpedo from British submarine Unbroken. Repair of battle damages it has been decided to combine with conversion to semi-aircraft carrier intended for carrying and launching of 12 Re.2000 fighters. Landing of aircrafts on the deck was not provided, after fulfilment of the task they should fly to nearest coastal airfields. For launch of aircrafts two catapults on forecastle were provided. Fighters were planned to store openly on the deck, thus all superstructures fwd from fore funnel were demounted, and the fore funnel was shared on two, moved to sides. All old armament was removed, assuming to change on 10 single 90mm/50 guns and 20 twin 20mm/65 MGs. After conversion displacement should be moderated to 9000/11800t. Actually conversion did not start.

Ship protection: 70-mm main belt expanded between fore side of "A" and aft side of "Y" barbettes and closed by 60-mm upper and 50-mm (fwd) or 40-mm (aft) lower bulkheads. 50-mm flat main deck connected with upper edge of main belt. Ship ends outside the citadel were protected by 20-mm lower deck with 30-mm slopes. Barbettes and communication tube had 70-mm protection above and 60-mm below the upper deck. CT had 100-mm sides, 40-mm deck and 50-mm roof. Director had 80-mm sides and 60-mm roof.

Modernizations: 1934: - 2 x 1 - 40/39

1937: - 2 x 2 - 100/47, 2 x 1 - 40/39; + 4 x 2 - 37/54 Breda 1932

1942: - 4 x 2 - 13.2/76; + 4 x 1 - 20/65 Breda 1940

Naval service: 25/8/1941 Bolzano was torpedoed by British submarine Triumph and was 3 months under repair. 13/8/1942 she was again damaged by torpedo from British submarine Unbroken and ran aground. A month later she was salvaged and towed to La Spezia but repair (and planned conversion to semi-aircraft carrier) was incomplete. 9/9/1943 Bolzano was captured at La Spezia by Germans. She was sunk 21/6/1944 by British Chariot type human torpedoes (with Italian crews), carried on Allied Italian MTB MS74.

Bolzano 1942

 

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Ivan Gogin, 2009-11