This is the URL for the National Archives website. It tells you where you might find naturalization records in the State of Wisconsin. http://www.archives.gov/research_room/genealogy/research_top...
If perchance this url doesn't work, try going to www.nara.gov
for their home page and search the site.
You were fortunate to find the name of the ship. I am still looking. My greatgrandfather emigrated from Germany either 1865 or 66. I know his port of entry was New York City but I have been unable to find him on any ship's lists.
Wishing you good success!