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New Mexico Class, U.S. Battleships


Photograph of New Mexico-class battleship

Naval Historical Center #NH-59949

Schematic of New Mexico class battleship

ONI 222


Specifications:


Tonnage 33,420 tons standard displacement
Dimensions 624' by 106'3" by 34'
190.20m by 32.39m by 10.36
Maximum speed       21.5 knots
Complement 1443
Aircraft 2 catapult
3 seaplanes
Armament 4x3 14"/50 guns
12x1 5"/51 guns
6x1 5"/25 AA guns
4x4 1.1"/75 AA guns
8x1 20mm Oerlikon AA guns
8 0.50 machine guns
Protection About 11,000 tons or 32.9% of displacement:

13.5" (343mm) belt tapering to 8" (203mm) below the waterline

2" STS + 1.75" STS + 1.75" NS = 4.2" (51mm STS + 44mm STS + 44mm NS = 107mm) armor deck

4.5" STS + 1.75" MS = 5.5" (114mm STS + 44mm MS = 158mm) over steering spaces

2" STS + 1" STS + 0.5"/1.5" STS + 0.5" MS = 3.1"/3.9" (51mm STS + 25mm STS + 13mm/38mm STS + 13mm MS = 79mm/99mm) splinter deck

13" (330mm) bulkheads tapering to 8" (203mm) below waterline

18"/5"STS/10"/9" (457mm/127mm STS/254mm/229mm) turret

13" (330mm) barbettes

Splinter protection for 5"/25 guns

16" (406mm) conning tower

9" (229mm) uptakes

19' (5.8m) underwater protection consisting of a 0.25" (6mm) retaining bulkhead, an inner 1.5"+1.5" (38mm+38mm) STS torpedo bulkhead, an outer 0.75" (19mm) STS torpedo bulkhead, and blisters. The system was designed to withstand a 300 lb (136 kg) explosive charge.
Machinery
4-shaft Westinghouse geared turbine (40,000 shp)
4 White-Foster (New Mexico) or 6 Bureau Express (other units) boilers
Bunkerage 3795 tons fuel oil
Range 12,500 nautical miles (23,000 km) at 18 knots
Modifications
New Mexico and Mississippi:

1942-11: 4 5" guns replaced with 2x4 20mm guns, 6x1 20mm guns.

1943: One catapult landed.

1943-10: Light antiaircraft upgraded to 6x4, 2x2 40mm Bofors AA guns and 24 to 29 20mm guns.

1944: 20mm battery increased to 50 guns.

Late 1944: Antiaircraft battery upgraded to 6 5"/51 guns, 10x4 40mm guns, and 40 to 46 20mm guns.

1945: Mississippi upgraded to 16 5"/25 guns, 12x4 40mm guns, and 40 20mm guns with conning tower removed to compensate.

Idaho:

1942: Antiaircraft upgraded to 8 5"/25 guns, 10x4 40mm guns, and 16 20mm guns.

1943-2: 20mm battery increased to 43 guns.

1945-1: All 5"25 guns removed and replaced with 10x1 5"38 dual-purpose guns.


The New Mexicos were completed in 1918. The third of the "standard battleship" classes, they were quite similar to the Pennsylvanias, a proposal to build 16" (406mm) gun battleships with heavier armor having been rejected by the Secretary of the Navy as too costly.  The newer ships were better sea boats, with clipper bows and a secondary battery located higher in the superstructure, and had improved subdivision. Their triple turrets were built up entirely of flat plates and incorporated independent sliders so that a hit on a single gun would not knock out all three. The guns were a more powerful 14"/50 model than the 14"/45 guns on the earlier ships.

In 1930, the ships were modernized, receiving an antiaircraft battery, a massive bridge structure, better endurance, and a modest amount of additional deck armor. The deck armor was believed capable of resisting a 1600 lb (726 kg) bomb dropped from up to 6000' (1830m). The casemate guns were removed and the casemates plated over.

Stationed in the Atlantic at the time of Pearl Harbor, the New Mexicos were hastily refitted with additional antiaircraft guns and rushed to the Pacific to form the backbone of a new battle line. This precluded any further modernization other than the installation of numerous additional antiaircraft weapons. Only the Idaho ever received the excellent 5"/38 gun.


Units in the Pacific:

Idaho

Arrived 1942-1-12

Mississippi

Arrived 1942-1-12

New Mexico      

Arrived 1942-1-12

Photo Gallery


Profile of Idaho

U.S. Navy

Forward quarter view of New Mexico

U.S. Navy

High forward quarter view of Mississippi

U.S. Navy

Bow view of Mississippi in dry dock

NARA

5" gun gallery on New Mexico

U.S. Navy

Reloading the main magazines of the New Mexico

U.S. Navy

Catapult of New Mexico

U.S. Navy

Kamikaze hit on New Mexico

U.S. Navy

References

DANFS

Friedman (1985)

Whitley (1988)

Worth (2001)



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