Triton Lumber sells Boat lifts. A Four Post Boat lift will require installation on top of Marine Grade Pilings.Your boat sits on top of the Boat lift Beams on Carpeted Bunks or Rubber Coated Bunks which are attached to the beams via Bunk Brackets.The bunks are lifted in and out of the water via Lift Cables which are rotated around by a Boat lift Motor.