A boarding/disembarking apparatus is removably attached to a vessel to assist in boarding and disembarking from the vessel. An upper end of the apparatus engages the vessel's gunwale or transom and the lower end of the apparatus defines a step or platform, and a hull plate rests against the hull. In a first embodiment the hull plate is hinged to conform to the angular hull of the vessel. In a second embodiment the hull brace allows adjustment of the position of the apparatus relative to the boat.