The SS Sagamo was designed by naval architect Arendt Engstrom of Cleveland, Ohio in 1905 based roughly on the design of the SS Cayuga a ship on the Toronto to Niagara run which Engstrom had just completed designing. The ship's steel hull was fabricated by the Canadian Ship Building Company in Toronto, Ontario and was assembled at the Gravenhurst, Ontario yard of the Muskoka Lakes Navigation and Hotel Company, the ship's owner and operator. The hull was riveted steel with a steel frame above and a wooden superstructure. She was powered by two Triple expansion steam engines and four Scotch marine boilers, developing 68.8 horsepower for a top speed of 18 mph.
The Sagamo was designed with two full decks above the hull, and two additional partial decks above those. On the main deck was the galley and the dining room which seated 90 people, and the washrooms. The promenade deck above had forward and aft lounges. On the third deck was a smoking lounge. The ship c