An add-on protective covering for a support piling on an existing marine structure. The add-on protective covering has two pieces. First is a generally U-shaped piece which fits around an existing piling. One end of the U-shaped piece, a sliding piece, will slide into place on connectors with the U-shaped piece and on the sliding piece. The connectors serve the dual purpose of holding the sliding piece in place and restricting water flow to the space inside the protective covering. Restricting water flow prevents the growth of marine organisms on the existing marine piling this is an add on protective covering for installed pilings in a salt water marine environment where marine borers attach pilings.