An apparatus is provided for moving a floating or submerged marine structure. Embodiments include a track fixedly mounted near or under the waterline surface, extending from a first point to a second point for defining a path of motion of the marine structure. A riser cable has a first end movably attached to the track between the first and second points, and a second end fixedly attached to the marine structure. A trolley is attached to the first end of the riser cable between the first end and the track, and has a roller for engaging the track for distributing environmental forces of the marine structure to the track. A drive unit is attached to the marine structure (or to the trolley) for moving the marine structure (or the trolley) such that the marine structure or one end of the marine structure moves along the path of the track.
