The Liberty Belle is still (as of 8pm on 9/20) behind the Swing Bridge by Thunder Mountian. Any rumors that she has been moved to dry dock are false. The riverboat can travel across Bay Lake and the Seven Seas Lagoon under her own power with the assistance of a tug (usually a pontoon boat or in the past a Keelboat). Her single smokestack is just able to clear the underside of the monorail beams between MK & GF.
As Celestia mentions there was a rehab incident with one of the original boats "The Joe Fowler" she was outfitted with a Fiberglass hull that did in fact break beyond repair during sudden change in altitude during that rehab. The boat was scrapped from the hull up and some of the pieces were used as decoration and theming around the parks.
The 2nd boat Richard F. Irvine/Liberty Belle has a steel hull. The Liberty Belle is a new boat built on the original Irvine hull. There is still an Irvine tribute deep in the "heart" of the Belle.