Modernization
Four months after Fleet Problem IX in January 1929, Arizona was modernized at the Norfolk Navy Yard. New tripod masts, surmounted by three-tiered fire-control directors for the main and secondary armament, replaced the old hyperboloid cage masts; the number of 5-inch (130 mm) guns was reduced to 12 and the guns re-positioned one deck higher, and eight 25-caliber 5-inch anti-aircraft guns replaced the 3-inch (76 mm) guns with which she had been originally equipped. The ship's main gun turrets were modified to increase the maximum elevation of their guns to 30°. The compressed-air catapult on the quarterdeck was replaced by one that used black powder. Her deck armor was increased by the addition of a 1.75-inch (44 mm) thickness of Special Treatment Steel and the ship was bulged to protect her from torpedoes. An additional bulkhead was added to the sides of the boiler rooms for the same purpose. Arizona's machinery was almost entirely replaced; her high-pressure turbines were replaced by more powerful geared turbines from the cancelled battleship Washington and six new boilers replaced her originals. Their additional power offset the ship's increased displacement as demonstrated during her sea trials; Arizona made 20.7 knots (38.3 km/h; 23.8 mph) with 35,081 shp (26,160 kW) at a displacement of 37,654 long tons (38,258 t).
Read more about this topic: USS Arizona (BB-39)