BOLZANO (Italy)

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D. v. Nieuwenhuijzen
Posts: 871
Joined: Fri Sep 24, 2010 7:46 pm

BOLZANO (Italy)

Post by D. v. Nieuwenhuijzen » Thu Jul 07, 2016 7:19 pm

Built by Ansaldo, Genova, laid down 11-06-1930, launched 31-08-1932, completed 19-08-1933.
Cruiser of the 'Trento' class with increased speed, displacement:10.890/13.665 tons,Loa:196,90m. Lbpp:187,60m. B:20,60m. Draft:6,80m. 10 Yarrow-Ansaldo boilers, 4 Parsons geared steam turbines:150.000 hp. 4 shafts, 36 kn. fuel:2224 tons oil, range: 4432 nm/16 kn. complement:725.
Armour in 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)

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 150.000hp, 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, 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 173.772 hp. power. Real (during daily service) speed also was appeared enough high: about 33kts.

13-08-1942 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 9000/11800 tons. 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: 25-08-1941 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 on 22 June 1944 in La Spezia by a British Chariot Mk I crew operating from the Italian destroyer Grecale. The two British crewmen of the Chariot were Sub Lieutenant Malcolm Causer RN and Able Seaman Harry Smith RN.
After the war she was refloated, and sold for scrap in 1947.

(Somaliland 2011, 1500 a. StG.?)
Internet.
Attachments
bolzano.jpg
bolzano 2.jpg

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