RORO and ro-ro are acronyms for Roll On/Roll Off; a type of ferry, cruiseferry, cargo ship or barge that carries wheeled cargo such as automobiles, trailers or railway carriages.

RORO vessels often have built-in ramps or land based ramps, which allow the cargo to be "rolled on" and "rolled off" the vessel when in port. This is in contrast to lo-lo (lift on-lift off) vessels which use a crane to load and unload cargo. It is significant that a RoRo's ramps can serve all of the vessel’s decks; otherwise it is a hybrid type (see below).

Unlike elsewhere in the shipping industry where cargo is normally measured by the Metric Ton, RoRo cargo will typically be measured in the more convenient unit of Lanes In Metres (LIMs). This is calculated by multiplying cargo length in metres by its width in lanes (lane width differs from vessel to vessel and there are a number of industry standards). Note that, whilst any vessel can be poorly or dangerously loaded, it is very unlikely that a RoRo vessel will become overladen as, unlike, say, a cargo of grain or oil, the majority of any cargo is in fact air.

While smaller ferries that operate across rivers and other short distances often have built-in ramps, the term RORO is generally reserved for ocean-going vessels.

Typically, new automobiles that are transported by ship around the world are moved on ROROs. These large new-car carriers are commonly called Pure Car Carriers (PCCs) or Pure Car Truck Carriers (PCTCs). The largest PCC currently in service is the MV Mignon, owned and operated by Wallenius Wilhelmsen Lines of Sweden, it can carry some 7,200 cars.

Crowley operates the largest RORO barges in the world between the United States and Puerto Rico carrying highway trailers, shipping containers on chassis, new and used cars, and oversized cargos on three decks. These barges are towed by ocean-going tugs and sail four times per week from Jacksonville, Florida to San Juan.

History

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The first RoRo ships were ferries carrying steam trains across rivers. One of the earliest was Firth of Forth ferry in Scotland which started in 1851 and operated nearly forty years until the completion of the Forth Bridge.

Durring WWII, landing craft were the first ships enable road vehicles to 'roll on'. Post war, the idea was adopted for merchant ships and short ferry crossings. The first RoRo service crossing the English channel began from Dover in 1953.

Before the 1950s carrying cars aboard a ship was a difficult task. Automobiles had their gas tanks emptied and their batteries disconnected before being hoisted into the ship’s hold, chocked and secured. Only the wealthiest people could afford to move a car this way. An American innovation helped address the problem.

In 1957 the US military issued a contract to the Sun Shipbuilding and Dry Dock Company in Chester, PA for the construction of a motorized vehicle carrier called Comet. The ship was unique, addressing the problem of moving cars across the ocean in several new ways. Rather than use a crane to load cars, Comet had a stern ramp and interior ramps so cars could drive right off the dock, onto the ship and into place. Loading and unloading was speeded exponentially. Comet also had a patented adjustable chocking system that locked the car into the deck and a powerful ventilation system to remove any exhaust gases that accumulated from vehicle loading.

Since 1970 the market for exporting and importing cars has increased dramatically and the number and type of RO/ROs has increased also. In 1973, Japan’s K Line built the European Highway, the world's first Pure Car Carrier, which carried 4,200 automobiles. Today’s pure car carriers (and their close cousins , the Pure Car/Truck Carrier) are distinctive looking ships that have a box-like superstructure running the entire length and breadth of the hull and are fully enclosed to protect their cargo. They typically have a stern ramp and a side ramp for dual loading of up to 6,500 vehicles, as well as extensive automatic fire control systems. Hybrid RO/ROs have also been built to carry vehicles inside and containers on the top deck. As for the Comet, it is still afloat as part of the US Ready Reserve Fleet.

Risks

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The seagoing RORO car ferry, with big external doors close to the waterline and a large vehicle deck with few internal bulkheads that are able to prevent large movements of flood water, has a reputation for being a high risk design. If any water enters the vehicle deck, it can begin setting up a free surface effect within the vehicle deck making the ship unstable and causing a capsize as happened with the following ROPAX vessels

• Princess Victoria in 1953 killing 132 people.
• Herald of Free Enterprise in 1987 killing 193 people.
• Jan Heweliusz in 1993 killing 55 people.
• Estonia in 1994 killing 852 people.
• al-Salam Boccaccio 98 in 2006 killing almost 1000 people.
• Queen of the North in 2006. Two people remain missing and are presumed dead following the sinking.

Variations of RORO

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The acronym ROPAX is used when a RORO vessel is equipped with cabins to accommodate passengers, usually several hundred.

The ConRo vessel, is a hybrid of a RORO and a container ship. This type of vessel generally has a below decks area used for vehicle storage while still able to stack heavy container freight on the top decks.

A RoLo vessel, is another hybrid vessel type which might have a ramp/ramps which serve the main internal decks but the cargo space on the upper decks is only accessible by crane.

Reference

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• IMO and ro-ro safety
• Ro-Ro shipping rates and online consumer guide

Ship types | Commercial item transport and distribution

Ro-Ro | RoRo-Schiff | Ro-ro-alus | Roulier | Kapal RO-RO | RORO | Supercargueiro Ro-Ro | RO-RO