roll-on, roll-off (Ro-Ro)
(shipping) A broad category of ships designed to load and discharge cargo which rolls on wheels. Broadly interpreted, this may include train ships, trailer ships, auto, truck and trailer ferries, and ships designed to carry military vehicles. A Ro-Ro vessel has a hinged ramp, typically offset at the stern, that allows motor vehicles (automobiles, trucks, trailers, farm tractors, etc.) to be driven on and off the vessel.
A Ro-Ro differs from a ferry in that a ferry is designed to carry vehicles and their individual drivers short to medium distances, whereas a Ro-Ro is designed to carry vehicles for wholesale transport without drivers for long distances. For example, a Ro-Ro would be used by an automobile manufacturer such as Honda or Volkswagen to transport hundreds of vehicles at a time across oceans to sell in another country.
Ro-Ro vessels may have as many as eight interior decks accessible by interior rampways. Ro-Ro vessels may also have deck cranes and/or the ability to carry standard ocean containers on deck. Also, oversize cargo can be loaded on flatbed or lowboy trailers or placed on deck.