an apparatus for protecting a boat from harmful contact with the piling of a dock is provided . the apparatus comprises a generally rigid , vertical , elongated tube , preferably made of pvc pipe and a hollow sleeve . the sleeve is preferably made of concentric layers of resilient and strength imparting material and has a hollow core aligned with the elongated axis of the tube . lag bolts extend from inside the core of the sleeve , through the sleeve and wall of the tube into a wooden 2 × 4 within the tube . also , lag bolts extend from inside the core of the sleeve , through the sleeve and into a piling . in this way , the tube is attached to the sleeve which is in turn attached to the piling . a seal and a cap with a vent are attached to the bottom and top of the tube respectively .