Gary, I just received a book from my aunt that traces back my grandmother's branch(Hemann>Kruse>Ernst). It describes just about exactly what you have. As the book reads, F.W.'s father's name was William Hemann. They took a sailboat across the atlantic in 1865 instead of a steamship and got into unfavorable winds. Their 7 week journey lasted 3 months. William had to be carried off the ship in New Orleans where they stayed for a few weeks. They then made it up the Mississippi to St Louis, then to Alhambra, IL, then to Staunton, IL where William died. William was returned to Alhambra and was buried in Salem Cemetary in an unmarked grave.
I'm very certain this is the same F.W. that you are describing. My book says they went to Kansas, then to Sarcoxie. If you'd like, I can ask my aunt how to get another copy.