Maybe the Lake Carriers Association might have some of the data you're looking for.
http://www.lcaships.com/
Shipping Data
Shipping Data
Hi, I'm new to this site, and am looking for information related shipping data for the Straits of Mackinac. Specifically, what I'm looking for is a breakdown of the number of ships navigating the Straits, broken down by size (i.e. Class, or displacement, or GRT, or Equipment Number, etc.). Any information anyone could provide to point me in the right direction would be greatly appreciated. Thanks!