The Italian Heavy Cruiser Pola

The Pola was a Zara-class heavy cruiser of the Italian Regia Marina operating during the Second World War.

She was the last of four ships in this class (Zara, Fiume e Gorizia were the other three), built in the Odero Terni Orlando shipyard in Livorno in 1930 she entered service in 1932.
At the beginning of 1928, the Italian Regia Marina, not to be disadvantaged compared to the other navies, needed to build new cruisers whose could be used with the Trento-class ships, while waiting until the economic resources of the Italian state allowed it to get new battleships or to renovate old ones like Cavour or Giulio Cesare.
Since there was a halt in building and the study of projects, the only existing one was what the Navy Ministry had prepared was for a Trento-class cruiser in which the thickness of the armour was increased to 150 mm.

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In fact, it was necessary to produce other cruisers more resistant to combat to the lighter ones, too vulnerable to constitute the core of the support units.
Keeping unchanged the armament and reducing slightly the speed it seemed possible that the vessels can be built without exceeding the standard displacement of 10,000 tons set by the Treaty of Washington.
Anyway the instructions for the study of these cuisers were not to determined from the beginning the displacement and not to be tie up to the limit imposed in Washington for the heavy cruisers.
It was also important that the new heavy cruisers had extensive vertical and horizontal protection, but also a robust hull structure. It was decided to equip them with a main armament of eight 203 mm guns, as on the Trento-class cruisers, and to provide them with an effective operating speed of 32 knots.

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To increase the protection of the new cruisers, providing them with a 200 mm armour without exceeding 10,000 tons, it was necessary to reduce the main armament to six 203 guns. This could be possible if there had been the economic resources necessary to order three ships, but at that time, it was hard to obtain it quickly. So the Italian Regia Marina ordered just two cruisers with sixteen guns instead of twelve, with an armament of eight 203 guns and reduced protection of 150 mm of armor.
In 1928 it was decided to build the first two Zara-class cruisers (namely Zara and Fiume) and later in 1929 the Gorizia and finally in 1930 the Pola. The building of the Pola cost 114 millions and 700.000 liras. Pola, at the end of the building, like the other three cruisers of the same class, all entered into service between 1931 and 1932, turned out to be 12,000 tons, although officially reported of 10,000 British tons.
Her motto was “I dare in any undertaking”.

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Design, propulsion and armour

Compared to the Trento-class, the Zara-class had a more squat hull, in fact their length was reduced by 14 metres, and it was less suitable for high speed. She had a big bridge structure, that included the fore bridge, the turret and the bow–funnel.
To give them good seakeeping they were equipped with a prow-castle and this solution, compared with the flush-deck of the Trento-class, had the advantage of a considerable saving of weight. The bow was straight ahead to the waterline and it had an arched and very flared shape up to the foredeck.
The stern was very rounded and the rudder was semi-compensed and similar to the Trento ones.
The hangar for the storage of the two floatplanes was built into the hull structure at the bow of the first 203 turret. An elevator lifted the floatplane on the castle bridge where the “Gagnotto” catapult was placed, which extended to the extreme bow.

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The ship was protected with a armoured belt that was 150 mm thick amidships. Her deck armor was 70 mm thick in the central portion of the ship and reduced to 20 mm at either end. The gun turrets had 150 mm thick plating on their faces and the barbettes they sat in were also 150 mm thick. The main superstructure had 150 mm thick sides.
The Pola was designed to function as a squadron flagship, so her forward superstructure was larger than that of her sisters, and was faired into the fore funnel.
The vertical protection consisted in a partial belt 150 mm thick at water-line and 100 mm in the lower side part. It continued between the two extreme turrets where it ended with a deck girder 120 mm thick. In height the armored belt reached the protected bridge 70 mm thick. The sides above the belt armor had 30 mm thick to the main deck, that was protected by steel plates 20 mm thick. The turrets and the 203 mm barbettes had 150 mm armor, as was also the armored structure for the direction of the shot. The steering –gear deck of the rudder was protected by a 20 mm bridge.

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The engine was made up of eight water-pipe boilers with Thornycroft overheaters. They produced steam to the maximum operating pressure of 25 kg/cm2 with a 60° overheating. The disposition of the boilers was in separated rooms: two at the bow of the prow engine and another one laterally from this; four in the center of the ship between the two groups of engines and another one laterally from the stern group. The boilers fed two “Parsons” steam turbines that fed power to a couple of three blade “Scaglia” screws.
Her engines were rated at 95,000 sh (71,000 kW) and produced a top speed of 32 knots (59 km/h; 37 mph).
The cruiser was built as a flagship with a larger superstructure to accomodate an admiral’s staff.
She had a crew of 31 officers and 810 men.

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