Abstract: A device for progressively cleaning the hull of a boat being moved forwardly along a prescribed path. The device includes a submersed stationary support frame. A hull cleaning framework is mounted to the support frame and is elevationally movable thereon between a partially submerged operative condition, and an above surface inoperative condition. A number of brush supporting arms are pivoted on the hull cleaner framework and extend along the path of a boat through the device at their outer ends. The arms are biased inwardly toward the path for yieldably urging the rotating brushes against the boat hull regardless of its configuration. The device will automatically adapt itself to a wide variety of power boat and sailboat hull shapes. Vertical brushes are provided to clean the downwardly projecting keels of sailboats. Transverse bottom, intermediate and side brushes are independently pivoted to accommodate sailboat hulls or many other forms of boat hulls.