CHICAGO (CBS) — It’s appearing more and more likely that the end is at hand for the Great Lakes’ oldest freighter, a ship with a unique tie to Chicago.

Bay Shipbuilders is referring all calls on the future of the ship once known as the Medusa Challenger to its owner, Port Cities Steamship Services, of Muskegon, Mich. Port Cities has not returned WBBM’s calls.

The Door County Advocate newspaper is reporting that Port Cities has awarded Bay a contract to transform the 107-year-old ship, now known as the St. Marys Challenger, into an un-engined barge. The Advocate said its future is as an articulated tug barge that would be pushed by a tug in the future.

Last week, Port Cities President Chuck Canestraight characterized the conversion as “modernization.”

“It’s time to do some modernizing, which is kind of funny after more than a century, but it’s certainly time to do some modernizing to create some longevity for that hull to trade in and out of Chicago and other Lake Michigan ports,” he said.

At 552 feet, the Challenger is the largest ship ever to traverse the Chicago River, which it did on a regular basis between 1968 and 1979 en route from the Medusa (now St. Marys) Cement plant in Charlevoix, Mich., to Goose Island. Since 1979, its southern port of call has been Lake Calumet.

When using the Chicago River, it left many bridge leafs frozen in the raised position, although it was always guided by tugboats on the river and never struck a bridge. The problems with bridges were so pervasive that in 1973, the Chicago Tribune once published an article that told readers that no bridges became stuck.

The ship was in Chicago as recently as Tuesday. As of Wednesday night, it was back in Michigan, but could have two trips left in its current configuration. It is due in drydock on or about Nov. 7.

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