Alaska Class Cruisers

The Alaska Class cruisers were effectively battle cruisers, designed to deal with a potential threat from heavily armoured Japanese and German cruisers that had evaporated by the time the two members of the class were completed. Both ships served with the Pacific Fleet during 1945.

Towards the end of the 1930s it became clear that the naval treaties that had limited warship construction amongst the Democratic powers were under threat. The German 'pocket battleships' were effectively battle-cruisers - fast, thinly armoured but heavily armed ships that outclassed any other existing cruisers. There were also rumours that the Japanese were building 'super-cruisers' of their own, although these were false - the only cruisers under construction in Japan in the mid to late 1930s were the four ships of the Mogami class (15 x 6.1in guns) and the two ships of the Tone class (8 x 8in guns), while the Kongo class battlecruisers were turned into fast battleships,

Side view of USS Guam
Side view of
USS Guam

The Bureau of Construction and Repair began to work on the design of a 12in cruiser in 1938, basing it on existing US heavy cruiser designs. This explains the use of a single rudder instead of the twin rudders of many larger ships, and the requirement for an enclosed aircraft hanger.

The final design for the Alaska class ships was approved in mid-1941. The US Navy considered them to be large cruisers, although the CB designation does suggest that the battlecruiser wasn't far from their mind.

The Alaska class cruisers were armed with a new 12in/50 gun, and were the only American ships of the Second World War to carry that gun. Early plans called for eight guns in two triple and one twin turret. That was later increased to nine guns in three triple turrets to simplify construction by removing the need to design two different types of turret.

Secondary armament was provided by twelve 5in/38 guns in six twin turrets, 56 40mm Bofors guns in quad mounts and 34 20mm Oerlikon cannons.

Their armour was designed to protect against 12in 1140lb shells hitting at 60 degrees between 18,000 and 24,000 yards, similar to the standard heavy cruiser specifications. In early designs the machinery space was outside this protected zone, but this would have left the 5in magazines unprotected and so the belt was expanded. A total of 4,720 tons of armour was carried, 16.4% of the total displacement. This was a higher proportion than on US heavy cruisers, but lower than on US battleships, where around 40% of the displacement went on armour.

The Alaska class has been described as the logical final step in the design of the heavy cruiser, unrestricted by treaty limits. However the Baltimore class cruisers also fit into that category, and they were much smaller ships - over 130ft shorter, with half the loaded displacement, nine 8in guns, and thinner armour in just about every location. Both types were rated at 33kts, and surprisingly the Alaska class ships carried a significantly smaller crew.

Their layout was similar to that of the Baltimore class ships, even down to the wide stern (even though the aircraft were stored amidships and not in the stern). Instead the space was used for some of the secondary armament. The gap between the funnel and the forward superstructure was used to house the aircraft and two catapults.

By the time the first two Alaska class ships were ready for service early in 1945 naval warfare had changed beyond all recognition when compared to pre-war expectations. The aircraft carrier was king, the surviving pocket battleships spent their limited time at sea operating in the Baltic and the Japanese surface fleet was no longer a threat, having suffered a final crushing defeat at the battle of Leyte Gulf (23-26 October 1944).

Six Alaska class ships were ordered, but only three were laid down - Alaska (CB-1) and Guam (CB-2) in December 1941 and February 1942 and the Hawaii (CB-3) nearly two years later in December 1943. The delay was caused by a shortage of steel. Changing circumstances meant that the last three ships were cancelled in June 1943.

Alaska was completed in June 1944 and Guam in September 1944, and they both joined the Pacific Fleet early in 1945. Neither ship had a long post-war career - the Baltimore class ships were perfectly capable of carrying out any cruiser duties that were expected, and the Alaska class ships were much more expensive to maintain.

USS Alaska (CB-1)

The Alaska joined the fleet in mid-January 1945. She took part in the fighting on Iwo Jima and Okinawa, and supported the carrier task forces during raids on the Japanese Home Islands on in the East China Sea. She was decommissioned in February 1947.

USS Guam (CB-2)

The Guam reached the fleet on 8 February. She took part in the fighting off Okinawa, and raids on the Japanese Home Islands and East China Sea. She was also decommissioned in February 1946.

USS Hawaii (CB-3)

The Hawaii was launched in March 1945, but was never completed. Plans were put in place to turn her into a missile cruiser and later into a command ship, but neither conversion took place and she was eventually broken up in 1960.

Displacement (standard)

29,779t

Displacement (loaded)

34,253t

Top Speed

33kts

Range

12,000nm at 15kts

Armour – belt

5-9in

 - armour deck

3.8-4in
1.4in weather deck
0.625in splinter deck

 - barbettes

11-13in

 - turrets

12.8in face
5in roof
5.25-6in side
5.25in rear

 - conning tower

10.6in
5in roof

Length

808ft 6in

Armaments

Nine 12in/50 guns (three triple turrets)
Twelve 5in/38 guns (six double positions)
Fifty six 40mm guns (14 four gun positions)
Thirty four 20mm guns

Crew complement

1,517

Ships in Class

Fate

CB1 USS Alaska

Broken up 1961

CB2 USS Guam

Broken up 1961

CB3 USS Hawaii

Broken up 1960

CB4 USS Philippines

Cancelled 1943

CB5 USS Puerto Rico

Cancelled 1943

CB6 USS Samoa

Cancelled 1943

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How to cite this article: Rickard, J (14 August 2015), Alaska Class Cruisers , http://www.historyofwar.org/articles/weapons_alaska_class_cruisers.html

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