Roll-on/roll-off (RORO) ships are designed to carry wheeled cargo like cars and trucks. They have built-in ramps that allow cargo to efficiently roll on and off the vessel when in port. RORO vessels come in various types including ferries, cargo ships, and barges. One of the earliest RORO ships was a ferry carrying trains across rivers in Scotland in 1851. During World War II, landing craft introduced the ability for vehicles to directly roll on and off ships, which was later adopted for merchant vessels and short ferry crossings. Modern car carriers known as pure car carriers (PCCs) or pure car/truck carriers (PCTCs) can carry thousands of vehicles

1. Roll-on/roll-off
Loading a ro-ro passenger car ferry
Roll-on/roll-off (RORO or ro-ro) ships are designed to carry wheeled cargo such as
automobiles, trailers or railway carriages. This is in contrast to lo-lo (lift on-lift off)
vessels which use a crane to load and unload cargo.
RORO vessels have built-in ramps which allow the cargo to be efficiently "rolled on" and
"rolled off" the vessel when in port. While smaller ferries that operate across rivers and
other short distances still often have built-in ramps, the term RORO is generally reserved
for larger ocean-going vessels.
Contents
[hide]
• 1 Types
• 2 History
• 3 Car carriers
• 4 Risks
• 5 Benefits
• 6 Variations of RORO
• 7 See also
• 8 References
• 9 External links
[edit] Types

2. Spirit of Vancouver Island: A Canadian RORO Ferry
Another Canadian RoRo Ferry, the "Chi-cheemnaun" Operating on Lake Huron
The Cetus Leader, a 6500 unit PCTC
The Pride of Burgundy, a P&O Ferries passenger car ferry on the Dover-Calais English
Channel route which can carry 600 cars. [1]
Various types of RORO vessels include ferries, cruiseferries, cargo ships, and barges. A
true RORO's ramps can serve all of the vessel’s decks; otherwise it is a hybrid type. New
automobiles that are transported by ship around the world are often moved on a large
type of RORO called a Pure Car Carrier (PCC) or Pure Car Truck Carrier (PCTC).
Unlike elsewhere in the shipping industry where cargo is normally measured by the
metric tonne, RORO cargo will typically be measured in the more convenient unit of
lanes in meters (LIMs). This is calculated by multiplying cargo length in meters by its
width in lanes (lane width differs from vessel to vessel and there are a number of industry

3. standards). Aboard PCCs cargo capacity is often measured in RT or RT43 units which is
based on a 1966 Toyota or by car equivalent units (CEU).
The largest RORO barges in the world operate 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
At first, wheeled vehicles carried as cargo on oceangoing ships were treated like any
other cargo. Automobiles had their gas tanks emptied and their batteries disconnected
before being hoisted into the ship’s hold, where they were chocked and secured. This
process was tedious and difficult, and could not be used for routine travel.
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 for nearly forty
years, until the completion of the Forth Bridge.
Ferries hauling rail cars were used after the US Civil war in New York harbor, the Great
Lakes and the St. Clair River in Detroit. By the latter quarter of the century, car ferries
were a common sight in San Francisco and Puget Sound. A car ferry worked the
Columbia River for many years at Kalama for the Northern Pacific Railway. By the turn
of the century, car ferries became important adjuncts to railway systems particularly
those which were discontinuous due to geography. Montreal, Newfoundland, Prince
Edward Island, and the Islands of Japan were all cut by water, and thus needed ferries.
Russians used car ferries on Lake Baikal to move rail cars while the line was finished.
Carrier Princess, Seaspan Coastal Intermodal ferry in Active Pass. March, 2007.
During WWII, landing craft were the first ships enabling road vehicles to roll directly on
and off. 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.

4. In 1957 the US military issued a contract to the Sun Shipbuilding and Dry Dock
Company in Chester, PA for the construction of a new type of motorized vehicle carrier.
The ship, Comet, had a stern ramp as well as interior ramps which allowed cars to drive
directly from the dock, onto the ship, and into place. Loading and unloading was speeded
dramatically. Comet also had an adjustable chocking system for locking cars onto the
decks, and a ventilation system to remove any exhaust gases that accumulated during
vehicle loading.
Car carriers
Skaugran Oslo
A PCC ship's starboard side showing side ramp.
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 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 with a box-like superstructure running the entire length and breadth of the
hull, fully enclosing and protecting the cargo. They typically have a stern ramp and a side
ramp for dual loading of many thousands of vehicles, as well as extensive automatic fire
control systems.
The PCTC has liftable decks to increase vertical clearance as well as heavier decks for
"high and heavy" cargo. A 6500 unit car ship with 12 decks can have three decks which
can take cargo up to 150 tons with liftable "panels" to increase clearance from 1.7 meters
to 6.7 meters on some decks. Lifting decks to accommodate higher cargo reduces the

5. total capacity. The largest PCC currently in service is the MV Mignon, which can carry
up to 7,200 cars.
Risks
The seagoing RORO car ferry, with large external doors close to the waterline and open
vehicle decks with few internal bulkheads, has a reputation for being a high risk design
(to the point where the acronym is sometimes derisively expanded "Roll On/Roll
Over"[1]
). An improperly-secured loading door can cause a ship to take on water and sink,
as happened for example with the Herald of Free Enterprise in 1987. Also, water
sloshing on the vehicle deck can set up a free surface effect making the ship unstable and
causing it to capsize.
Benefits
While the characteristics of seagoing RORO car ferries have inherent risks, there are
benefits to its seaworthiness. For example the car carrier Cougar Ace listed 80 degrees to
its port side in 2006 but did not sink, since its high enclosed sides prevented water from
entering.
Variations of RORO
The acronym ROPAX describes a RORO vessel equipped built primarily for freight
vehicle transport but also with passenger accommodation normally limited to less then
500 passengers. The term is also used for some ferries which usually carry large amounts
of freight vehicles and more than 500 passengers such as P&O Ferries' Pride of
Rotterdam, Brittany Ferries' Barfleur and Marine Atlantic's Caribou and Joseph and
Clara Smallwood.
The ConRo vessel is a hybrid between a RORO and a container ship. This type of vessel
has a below-decks area used for vehicle storage while stacking containerized freight on
the top decks.
A RoLo vessel is another hybrid vessel type with ramps serving vehicle decks but with
other cargo decks accessible only by crane.