Vincent's Houseboat is where Vincent Keller lived after being kidnapped and brainwashed by Muirfield, specifically by Robert Reynolds. It was located on the 79th Street Boat Basin in New York.
The houseboat was used to show who Vincent was separate from Catherine Chandler, developing his character. Vincent spent the majority of his time there when he and Catherine broke up. Catherine often felt uncomfortable being there, as it reminded her of how Vincent was taken away from her.
Tori Windsor also lived in the houseboat when she & Vincent were dating, until she died. After Vincent and Catherine got back together, Vincent would more often stay at Catherine's place than at the houseboat. He later moved out into Catherine's apartment after they got engaged.
Though Vincent was planning to sell the houseboat, it was destroyed in an explosion by Bob & Carol Hall, who were trying to kill Catherine & Vincent.

The houseboat is destroyed