Pensacola-class cruiser

The Pensacola class was a class of United States Navy heavy cruiser, the first "treaty cruisers" designed under the limitations set by the Washington Naval Treaty, which limited cruisers to a maximum of 10,000 long tons (10,160 t) displacement and a maximum main battery caliber of 8-inch (203 mm).

USS Pensacola (CA-24)
Class overview
NamePensacola-class cruiser
Builders
Operators United States Navy
Succeeded byNorthampton class
Built1926-1930
In commission1929–1947
Planned2
Completed2
Retired2
Preserved0
General characteristics
TypeHeavy cruiser
Displacement
  • 9,100 long tons (9,246 t) (standard)
  • 11,512 long tons (11,697 t) (full)
Length
  • 570 ft (170 m) wl
  • 585 ft 6 in (178.46 m) oa
Beam65.0 ft (19.8 m)
Draft19.5 ft (5.9 m)
Installed power
  • 8 boilers
  • 107,000 hp (80,000 kW)
Propulsion
  • Steam turbines
  • 4 Screws
Speed32.5 kn (60.2 km/h; 37.4 mph)
Complement1,200[1]
Armament
Armor
Aircraft carried2
Aviation facilities

Description

In an effort to remain within treaty limits, while still mounting a very heavy main battery of ten 8-inch (203 mm) guns, the hull was of welded construction, and the armor belt was thin (varying from 2.5 to 4 inches (64 to 102 mm) in thickness). This was inadequate to protect her vitals from enemy 8-inch shells and was no thicker than the armor on 6-inch (152 mm) gun cruisers. In fact, Pensacola and Salt Lake City were classified as light cruisers due to their minimal armor until re-designated in July 1931, as heavy cruisers in accord with international practice of designating all cruisers with guns larger than 6-inch as heavy cruisers.

Their main armament consisted of ten 8-inch guns, in two twin turrets on the main deck, and two triple turrets two decks above, making it one of the two US Navy ship classes (besides the Nevada-class battleships) to have different-sized turrets for main armament. All the guns in each turret were mounted in a single slide, and were unable to elevate independently of each other. Also, unlike the very few other ships with different sized main battery turrets (Nevada-class battleships and King George V-class battleships) the Pensacolas had the larger turrets superfiring over the smaller turrets, whereas the others had the larger turrets on "bottom".[2] Placing heavier turrets above lighter ones allows for finer lines for a given length, however this causes top heaviness and reduces stability.

Unfortunately, because of the rather unusual main battery layout and their heavy tripod fore-masts, they were top-heavy and prone to excessive rolling. This combined with low freeboard forward made them inferior seaboats compared to later designs. Rework in the shipyards modified the hull and superstructure in the 1930s to eliminate the rolling.[3]

The Navy built only two ships in this class before switching to the Northampton-class design. Many of the deficiencies of the Pensacolas were corrected by reducing the main battery to three triple turrets (two forward, one aft) and adding another upper deck forward of amidships.

Ships in class
Construction data
Ship name Hull no. Builder Laid down Launched Commissioned Decommissioned Fate
Pensacola CA-24 New York Navy Yard, Brooklyn, New York City 27 Oct 1926 25 Apr 1929 6 Feb 1930 26 Aug 1946 Struck, 28 Nov 1945; Sunk as target, 10 Nov 1948
Salt Lake City CA-25 New York Shipbuilding Corporation, Camden, New Jersey 9 Jun 1927 23 Jan 1929 11 Dec 1929 29 Aug 1947 Struck, 18 Jun 1948; Sunk as target, 25 May 1948

See also

References
  1. Silverstone, Paul H (1965). US Warships of World War II. Annapolis, Maryland: Naval Institute Press. ISBN 0-87021-773-9.
  2. the original design for the Lexington-class battlecruiser would have shared this unique arrangement, as they called for ten 14-inch (360 mm) guns, with the triple turrets superfiring over twin turrets, and would have appeared like scaled up Pensacolas
  3. Silverstone, Paul H (1965). US Warships of World War II. Annapolis, Maryland: Naval Institute Press. ISBN 0-87021-773-9.
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