The occupation of serving on a ship was a important one in the early days of Southeast Michigan. As the area developed it became much more common in cities like Monroe and Detroit. Inter lake trade and transportation began as early as the 1800's, but really increased once the canal system was established.
Ships in those days would start from Buffalo at the eastern end of Lake Erie. This was the western edge of the Erie canal. A common cargo at this time was moving settlers from the east to points along the eastern edge of Michigan and points beyond. Eastern supplies from industrial companies were also a common cargo. They would then transport on a very regular basis to the growing areas in Michigan.
Once they arrived in Southeast Michigan they then would transport about anything that could fit in a barrel back in East. Transport of food, raw materials like wood and stone were common. The trade would help the area become more prosperous and would work as a draw for people to the area.
Life as a sailor on a ship was a difficult one during this period of time. Ships were powered by the wind and later steam. Many people from the New England area had participated in these occupations prior to moving so it was often a life style they new very well.
The National Archives has records for people that were sailors on the Great Lakes. They are much later in time, but may shed light on your ancestors. The file is RG 85 which includes 91 rolls of microfilm.