The LCM-8 ("Mike Boat") is a river boat and mechanized landing craft used by the United States Navy and Army during the Vietnam War and subsequent operations. They are currently used by governments and private organizations throughout the world. The acronym stands for "Landing Craft Mechanized, Mark 8". (The "Mike Boat" term refers to the military phonetic alphabet, LCM being "Lima Charlie Mike".)
The vessel weighs 135,000 pounds (61,200 kg) and has a crew of four: a Boatswain's Mate petty officer, an Engineman petty officer, a non-rated fireman, and a seaman. US Army specifications call for a crew of six during 24-hour operations: two coxswains, two seamen and two enginemen. The LCM-8s are constructed from welded steel and powered by four 6-71 or two 12V71 diesel engines, twin propellers, and rudders. The ship can carry 60 short tons of cargo. It was designed by Marinette Marine Corp. It has a range of 190 miles at 9 knots with a full load.
Modifications
A modified version, the Zippo boat, carries flamethrowers. Another modified version, the LCM-8 Mod 2, was used to fulfill command, personnel, salvage, and firefighting functions. There is also another version with an aluminum hull. This version was carried aboard all of the Charleston class LKA ships, as the steel version was too heavy to be lifted by the ship's 40 ton fore and aft booms, preventing more than two from being lowered (via the two 70 ton fore and aft cargo booms) at one time. They are now mostly carried by pre-positioned ships.
A third modification was as a transport for PBRs (patrol boat, river) from repair stations at Da Nang (YR-71) and Tan My (PBR Mobile Base 1) to outlying points at Cua Viet, and the Cua Dai rivers. PBR main propulsion jet pumps were easily damaged by ocean salt water which necessitated the boats being carried by another craft to their duty stations. These transport LCMs were classed as mini-docks and each had a boat ramp in the well deck. The voids (built-in float chambers under the well deck) would be systematically flooded, allowing the front end of the craft to sink, so a PBR could be floated in or out of the well deck. The pumping mechanism would then be reversed to clear the water out of the voids, restoring the craft to the normal floating position.
A fourth modification was the Army Version for Vietnam Rivers Logistic with a liveaboard cabin and crewed by 6 men consisting of Coxswain, Assist. Coxswain, Engineer and assistant and two deckhands. All crew could handle the two 50 Caliber Machine gun turrets and other small arms and were frequently engaged by the Vietcong on the rivers and canals of the Mekong Delta. One unit, an Army Reserve Unit out of St. Petersburg, Florida, was called to active duty in 1968-69 received a Unit Commendation of merit for delivering record tonnage in their 12-month tour. 182 Men came back alive.
U.S. usage
They were used by the United States Navy and Army during the Vietnam War. During the Vietnam War, there were two new aluminum LCM-8s on Johnston Island, which carried trucks and cargo between islands, and one being used as a rescue boat. They had the newer fluid shift transmissions, and 2-671's paired up to two props.
In I Corps (the northernmost military district in Vietnam) boats based at Da Nang, Tan My and Cửa Việt had three man crews of various rates and ranks. On U.S. Navy boats, the senior rate was usually a third-class petty officer or above, and the two crewmen could be E-2, E-3 or E-4 ranks (i.e. seaman apprentice, seaman, or petty officer third class). One of the two crewmen was almost always an Engineman and could be an ENFA, ENFN, or an EN3 in rank. The LCM-8s there all had two sets of the twin 6-71 Detroits paired up to a hydro transmission. Two air compressors, port and starboard of the engine sets, provided air pressure to operate the air cylinders that raised and lowered the bow ramp. The air cylinders were below deck in the eighth void from the bow and stretched cables attached to the ramp to raise it. Lowering the ramp was accomplished by releasing the air and allowing gravity to bring the ramp down.
They also saw use during Operation Just Cause in Panama as well as Operation Desert Shield and Operation Desert Storm. Three Army LCM-8s served in the 1992–1993 US mission to Somalia (fictionalized in Christian Bauman's 2002 novel The Ice Beneath You, which is set in part on a US Army LCM-8 near Kismaayo, Somalia), and a platoon of LCM-8s from the 1098th Trans Co. deployed to Port-au-Prince for the Haitian invasion (1994). The United States Army Reserve's 464th Transportation Company assisted the United States Coast Guard in patrolling the Potomac River after the terrorist attacks on September 11, 2001.