Manitowoc Shipbuilding Company

Manitowoc Shipbuilding Company, located in Manitowoc, Wisconsin, was a major shipbuilder for the Great Lakes. It was founded in 1902, and made mainly steel ferries and ore haulers. During World War II, it built submarines, tank landing craft (LCTs), and self-propelled fuel barges called "YOs". Employment peaked during the military years at 7000. The shipyard closed in 1968, when Manitowoc Company bought Bay Shipbuilding Company and moved their shipbuilding operation to Sturgeon Bay.

Shipyard President Charles C. West contacted the Bureau of Construction and Repair in 1939 to propose building destroyers at Manitowoc and transporting them through the Chicago River, Chicago Sanitary and Ship Canal, Illinois River, and Mississippi River in a floating drydock towed by the tugboat Minnesota. After evaluating the plan and surveying the shipyard, the Navy suggested building submarines instead. A contract for ten submarines was awarded on 9 September 1940. The Navy paid for lift machinery on Chicago's Western Avenue railroad bridge to clear a submarine. The 15-foot-draft submarines entered the floating drydock on the Illinois River to get through the 9-foot-deep Chain of Rocks Channel near the confluence of the Mississippi and Missouri Rivers. Submarines left the drydock at New Orleans and reinstalled periscope shears, periscopes, and radar masts which had been removed to clear bridges over the river.

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