A whip-style boat mooring apparatus, removably attachable to a standard dock cleat. The apparatus may include a second cleat, such that the apparatus provides both whip-style and standard cleat mooring from a single dock point. In one embodiment, the apparatus includes a clam-shell type housing, with a profile substantially resembling the dock cleat, such that the apparatus can be clamped to the dock cleat and prevent rotational movement. The housing may include two opposing pieces, attachable to respective sides of the dock cleat. The housing may include a rotatably adjustable means for attaching a whip socket onto the housing.