In the 1920s the Muskoka Lakes saw strong growth in tourism as the Canadian economy recovered from the trauma of World War I.

[1] Rather than commission an entirely new boat, management decided to convert the decommissioned SS Nipissing from a paddle-wheeler to a twin propeller passenger steamer.

When Segwun was rebuilt on the hull of the second SS Nipissing she was also converted from a side paddle wheel steamer with a walking beam engine into the current two counter-rotating propellers.

The conversion was performed at the Navigation Company's yard in Gravenhurst, Ontario during the fall and winter of 1924–5, at which time the bulk of Nipissing's machinery was removed, including her engines.

Workers installed a new Scotch marine boiler along with two secondhand Doty compound steam engines and stack.

While originally she was intended to retain the Nipissing name, the extent of the alterations were so extensive that the Navigation Company chose to rename her Segwun, an Ojibwa word meaning "springtime".

Additionally a new steel bulkhead salvaged from Medora was installed in the forward hold to create a crew sleeping area.

The Muskoka Lakes Lines, then owner of Segwun and the remaining steamships of the Muskoka Lakes Navigation and Hotel Company, already suffering from declining passenger and freight business due to new competition from the automobile and trucking lines, lacked the resources to re-fit the entire fleet.

The Muskoka Lakes Lines filed bankruptcy and the ships were repossessed by the Navigation Company who chose to fit the required equipment only on the flagship Sagamo and her companion Segwun.

Unfortunately, on his first trip, the captain bumped the swing bridge at Port Carling, almost disabling it, then later struck the concrete dock at the Lockmaster's house, resulting in a badly dented forepeak.