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LCM Class, Allied Landing Craft


Photograph of LCM-type  landing craft

National Archives #26-G-2386

Schematic diagram of LCM

ONI 226


Specifications:


Tonnage 26 tons light displacement
Dimensions 50' by 14'1" by 3'
15.24m by 4.29m by 0.91m
Maximum speed       11 knots
Complement
4
Armament
2 0.50 machine gun
Protection
0.25" (6mm) STS around the cab
Machinery
2-shaft diesel (220-550 shp)
Range
850 miles (1370 km) at 6.25 knots
500 miles (800 km) at 7.25 knots
140 miles (225 km) at 11 knots
Capacity 1 30-ton tank or 30 tons of cargo or 60 troops
Variants
The LCM(R) carried 32 T-45 rocket launchers (for a total of 384 rockets) and 4x1, 2x2 0.50 machine guns. Others were field-modified to carry a 37mm gun, two 20mm guns, and a pair of twin 0.50 machine guns in salvaged aircraft turrets.


Landing Craft, Mechanized, were small landing craft capable of transporting a tank or other vehicle from an attack transport to the beachhead.  They resembled sturdy LCVPs.

The LCM was originally known as the W-boat and was designed in 1941 specifically to be a tank lighter. However, the craft was criticized, particularly by the Marines, for having too deep a draft when loaded with a tank. The LCM was barely large enough to carry a Sherman tank in any case. Loading the tank into the LCM from the deck of a transport was difficult and hazardous, taking fifteen minutes under ideal conditions and likely twice that long in combat. As a result, the LCT became the principal tank landing craft and the LCM was pressed into service as a truck landing craft.

By late 1943, experience had shown that cargo must get off a landing beach as quickly as possible. This required LCMs to carry the trucks with which to move the cargo inland, and attack cargo ships were modified to carry more LCMs. This was done by adding quadrupod masts to allow some of the LCVPs to be replaced with LCMs and others to be nested within the LCMs.

Total Production

The following table gives total production.  About 33% of this was allocated to the Pacific until the final year of the war, when most of the amphibious fleet began to be shifted to the Pacific.

1940-1941     
125
1942-1 to 1942-6     
84
1942-7
118
1942-8
307

1942-9     

131

1942-10     

203

1942-11

244

1942-12
168
1943-1
114
1943-2
156
1943-3
406
1943-4
143
1943-5
236
1943-6
146
1943-7
244
1943-8
401
1943-9
502
1943-10
585
1943-11
563
1943-12
523
1944-1
578
1944-2
641
1944-3
594
1944-4
470
1944-5
487
1944-6
446
1944-7
441
1944-8
421
1944-9
411
1944-10
293
1944-11
222
1944-12
206
1945-1
135
1945-2
133
1945-3
120
1945-4
102
1945-5
93
1945-6
99
1945-7
104
1945-8
101


References

Friedman (2002)

Hyperwar: U.S. Navy Small Landing Craft (accessed 2007-12-29)
Leighton and Coakley (1955)

Marston (2005)

USS Rankin (accessed 2007-12-29)



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