As far back as the early 1830s companies around the world had been building railroad car ferries which allowed complete railcars to be loaded. Initially they were wooden craft but in 1897 the first all-steel carferry was introduced – the (later given the number 15). Mercereau organized and managed the ship for the railroad company and started ordering more steel carferries to add to the company's existing fleet of wooden carferry ships. He became the Superintendent of Steamships for the Pere Marquette Railway in 1899. The next steel carferry for the railroad company was the SS Pere Marquette No. 17, which was basically the same as Pere Marquette No. 15 except with more extensive cabin accommodations. Mercereau completely planned and oversaw the construction of this steel vessel that was built in a shipyard in Cleveland in 1900. His wife Louise christened the ship in 1901 when it was officially launched. The Flint and Pere Marquette Railroad company meanwhile in 1901 acquired another railroad company that already operated a wooden carferry. This carferry originally was called the SS Muskegon and but was renamed as the SS Pere Marquette No. 16 as the second carferry in its fleet. Mercereau ordered and supervised the construction of another steel carferry that was given the title Pere Marquette No. 18. With business growing rapidly, he ordered two more steel carferries. These became SS Pere Marquette No. 19 and SS Pere Marquette No. 20 that were also built in Cleveland. Mercereau eventually had built the SS Pere Marquette No. 21 and No. 22 and other all steel carferries. Mercereau engineered and supervised the development of the Pere Marquette fleet of train carferries for the railroad company. He was known in the railroad industry as the "Father of the Fleet" since he gave 31 years of service to the Pere Marquette Railway. Mercereau became the organizer and operator of the world's largest carferry fleet during his working career. He was also known as the 'father of the railroad on the water' because he brought to fruition the idea of loading the complete railroad car onto ferries across the Great Lakes for transportation as a complete loaded freight car unit. That increased overall profits for the commercial transportation industry in general in the long-term. He had ultimately developed Ludington into the home port of the world's largest carferry fleet. Later life and death on September 1, 1931, Mercereau