A system for protecting a dock from ice damage. The system includes a circumferentially fluted, water-impermeable housing capable of longitudinal and radial expansion and contraction. The housing defines a cavity with upper and lower openings into the cavity through the housing. The openings are configured and arranged to engage a dock-supporting post at longitudinally spaced upper and lower points along the length of the post with the upper point positioned above the water line and the lower point positioned below the frost line.