The William A. Irvin, Duluth’s floating museum ship, was moved into drydock at Fraser Shipyards in Superior on Thursday morning. The retired laker is expected to spend about the next four weeks undergoing repairs, causing one of Duluth’s most popular tourist attractions to miss a second season of operation.

The 611-foot-long vessel, a former member of the U.S. Steel Fleet, was forced to leave its long-held mooring at Minnesota Slip last summer to make way for crews that spent months shoring up failing seawalls and capping contaminated submerged sediments that had accumulated over years of port operations.

The Duluth Entertainment Convention Center, which owns and operates the Irvin, decided to make use of its displacement as an opportunity to tackle some deferred maintenance, including the repainting of its corroded steel hull. But the work has encountered delays, as the vessel had to wait its place in line at Fraser behind other working lakers in need of repairs, including the Arthur M. Anderson, which recently returned to service.

The DECC will be deprived of about $500,000 in annual revenues while the Irvin is sidelined.

The crew at Fraser began moving the Irvin at about 7 a.m. The entire process of moving a vessel into drydock and dewatering it typically takes about eight to 10 hours, said Jake Searl, a marine engineer and project manager for Fraser, who characterized the Irvin’s movement Thursday as smooth.

When all the water has been pumped out of the basin, the ship will undergo a structural inspection. The hull and then will be sandblasted and painted. Searl said Fraser also will be doing some work on the Irvin’s hatch crane.

The DECC received a $500,000 grant from the Minnesota Historical Society to cover the cost of the work.

The Irvin should be back in action and open to the public in plenty of time for the 2020 season, said Chelly Townsend, the DECC’s executive director.