I finally checked the series of books, "Germans to America: Lists of Passengers Arriving at U.S. Ports 1850-1897, 1840s" and looked for Mohelnitzky. I found nothing that sounded/looked close.

The last name is spelled wrong in so many places, though, so maybe I'll never find him on a ship list.

Here's my updated website URL:
http://sites.google.com/site/auswanderer20/Home/mohelnitzky