The SS William G. Mather was a 533-foot (162 m) long Great Lakes freighter that was built in 1905, by the Great Lakes Engineering Works (GLEW) of Ecorse, Michigan, for the Grand Island Steamship Company (managed by Cleveland-Cliffs Iron Company).

She was powered by a 2,000-horsepower (1,500 kW) triple expansion steam engine which was attached to a single fixed-pitch propeller.

After she was acquired by Gartland Steamship, she was converted to a self-unloading freighter by the Manitowoc Shipbuilding Company.

On April 5, 1972 the Nicolet cracked about 55 of her hull plates off Beaver Island on Lake Michigan when she was squeezed by ice.

[2] In 1974 the Nicolet had a new diesel engine installed by the Defoe Shipbuilding Company of Bay City, Michigan.

On December 29, 1979 the Nicolet's forward cabins were seriously damaged in a fire that broke out on her self-unloading gear when it was ignited by sparks from an acetylene torch, while she was being repaired in Toledo, Ohio by the Hans Hansen Welding Company.