Actually the marine fleet used to be operated as a subsidiary of the railway, which was the parent company, and the ships all used to have the Algoma Central _Railway_ logo on them. In the early 1990s they re-organized the whole company creating the Algoma Central Corporation as the parent company and the Railway, Marine, Real Estate, etc. operations as separate divisions, and sold off the railway division to WC.
Algoma Central Marine operates a fairly sizeable fleet on the Great Lakes, and they even a few oil tankers and at least one ocean-going vessel as well.