To replace the "Michipicoten", the OSTC purchased the S.S. "Macassa", then under the ownership of the Canada Steamship Lines subsidiary Richelieu and Ontario Navigation Company. The "Macassa" had completed her season on September 30, 1927, operating as a day excursion steamer between Toronto and Hamilton. The "Macassa" was originally part of the Toronto and Hamilton Steamboat Company, along with her sister ship, the S.S. "Modjeska". Over the following winter in Toronto, she was converted for the accommodation of overnight passengers. Renamed S.S. "Manasoo", she departed from Toronto for Owen Sound on April 16, 1928.