The United States Coast Guard Cutter Mackinaw WAGB-83 was built as part of the war effort during World War II to meet the heavy demands placed on industry for an increase in production of war materials.  Tremendous increases in the movement of iron ore, limestone and coal for the nation's steel mills were particularly necessary.  In order to keep tonnage on the move into the winter months an icebreaker was needed.  Congress authorized construction of Mackinaw on December 17, 1941, ten days after the attack on Pearl Harbor.  Funds were provided from a Special Presidential Fund used to expedite desirable projects.

Mackinaw was built in Toledo, Ohio at a cost of ten million dollars.  The keel was laid on March 20th, 1943 at the Toledo Shipbuilding Company, which had won the contract.  Various delays in completion involved such heavy penalties that the firm was forced into bankruptcy and the contract was taken over by the American Shipbuilding and Drydock Company.  The hull was launched March 4th, 1944 and Mackinaw was commissioned on December 30th, 1944. Cheboygan remained her home port her entire life.

With a length of 290 feet and a beam of 74 feet 4 inches, Mackinaw is the largest United States Coast Guard Cutter assigned to the Great Lakes.  Six Fairbanks Morse 10-cylinder, opposed-piston diesel engines drive generators that provide electrical power to turn two 14-foot diameter stern propellers each weighing 10.7 tons.  The engineering plant can develop 10,000 shaft horsepower to drive Mackinaw at a maximum speed of nearly 19 knots or 22 miles per hour.  A full load displacement of 5,252.4 tons produces a draft of 19 feet 2-1/4 inches.  When fully loaded, Mackinaw could carry 46,910 gallons of diesel fuel and 40,200 gallons of potable water.

When commissioned, Mackinaw was the most powerful and capable icebreaker in the world.  It is still the standard by which other icebreakers are measured.  The protective ice belt, which forms the lower hull, is constructed of steel plate 1-5/8 inches thick.  A number of innovative features were incorporated in the design to assist and improve the icebreaking capabilities.  Among these is a 12-foot diameter bow propeller, weighing 7.2 tons, which serves a dual purpose; first, it draws water from beneath the ice ahead – weakening it and letting it sag under its own weight, then it sends water streaming back along both sides of the hull reducing ice friction.  Mackinaw also has a heeling system that can shift nearly 112,000 gallons of ballast water from side to side in 90 seconds.  The rocking motion that this action produces assists Mackinaw in freeing itself if beset in the ice.

For 62 years Mackinaw continued to serve the Great Lakes Shipping industry, which is so vital to this region and the nation.  From December through April of every year Mackinaw responded to maintain the flow of commerce through the shipping channel of the Great Lakes and its connecting rivers.  In addition to icebreaking Mackinaw’s many missions included Search & Rescue, Aids to Navigation, and Public Relations.  Mackinaw is also recognized and utilized as an excellent training platform for officer Candidates, Academy Cadets, and Coast Guard Reservists.

Mackinaw was decommissioned on June 10th, 2006.  Her last voyage was from her working home of Cheboygan, MI to her retirement and namesake home of Mackinaw City, MI.  She arrived on June 21st, 2006 and was transferred to the Icebreaker Mackinaw Maritime Museum on June 30, 2006.