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Portland Class, U.S. Heavy Cruisers


Photograph
                  of Portland-class cruiser

Naval Historical Center #NH-97832

Schematic of Portland-class cruiser

ONI 54-R


Specifications:


Tonnage 10,300 tons standard displacement
Dimensions 610'4" by 66'1" by 21'
186.03m by 20.14m by 6.40m
Maximum speed       32.7 knots
Complement 807
Aircraft 2 catapults
4 seaplanes
Armament 9 8"/55 guns
8 5"/25 AA guns
8 0.50 machine guns
Protection 3" (76mm) belt (machinery)
5.75"(146mm) belt (magazines)
2.5" (64mm) deck
2.125" (54mm) magazine crowns
Machinery
4-shaft Parsons geared turbine (107,000 shp)
8 Yarrow boilers
Bunkerage 2125 tons fuel oil
Range 10,000 nautical miles (19,000 km) at 15 knots
Modifications:

Early 1942: Added 4x4 1.1"/75 AA guns, 12 20mm Oerlikon AA guns.

Late 1942: Added FC and FD fire control radars.

1943: Comprehensive radar suite installed, which included SK air search radar. 1.1" guns replaced with 4x4, 4x2 40mm Bofors AA guns.

1944: 20mm armament increased to 17-19 guns. One catapult landed and aircraft complement reduced to 2-3 aircraft.


The Portlands were completed in 1932-1933 and their design reflected the 1930 London Naval Treaty. The first group of ships of the 1929 naval program of 15 heavy cruisers were originally to be repeat Northamptons. However, this design was somewhat underweight relative to the treaty restrictions, and the newly imposed limits on total numbers of cruisers discouraged the building of second-class units. There was also a desire to develop a cruiser with better protection and with the range to counter German-style commerce raiders. Since three of the ships were being built in Navy yards, where major design changes in the midst of construction would not incur a large cash penalty, it was decided to modify two of on the ways with some of the desired improvements. Increasing the side belt was prohibitively expensive, but fairly heavy armor was placed around the magazines. The third ship was completed as Wichita.

The ships ended up rather top heavy, which caused them to roll badly, and Indianapolis capsized after a single torpedo hit.


Units in the Pacific:

Indianapolis      

Task Force 3 (Brown) at Johnston Island Torpedoed 1945-7-30  by I-58

Portland

Task Force 12 (Newton, Lexington) en route Midway      


Photo Gallery


Profile of Portland class

U.S. Navy

Bow of Portland class showing 1942 radars

U.S. Navy

Bow of Portland class showing 1944 radars

U.S. Navy

Forward part of Portland class

U.S. Navy

Midhips part of Portland class

U.S. Navy

Aft part of Portland class

U.S. Navy

Bridge of Portland class

U.S. Navy

ONI 54-R page on Portland class

ONI 54-R

ONI 54-R page on Portland class

ONI 54-R


References

DANFS

Whitley (1995)

Worth (2001)



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