In a google search of news i find this link
http://news.google.com/archivesearch?q=american-cruises+savannah-sun&scoring=a&hl=en&ned=us&um=1&sa=N&cid=8547289861722241
It only give a little info and when i click on the first link its a pay-per-view archive page
From the little text that shows in the search, it would appear to be a Georgia day cruise that didnt open.

"Pay-Per-View - Atlanta Journal-Constitution - NewsBank - Mar 15, 1990
... an officer of American Cruises Inc., which is restoring a 250-foot ferry it ... Like other ships, Mr. Cuquet's ferry, the Savannah Sun, would take up to ... "