Types of Ships: Roll on/Roll off Ships

75% of land is covered with water; hence it must be put to optimum use for transporting various goods from one place to another. There are various other means of transport like cars, trucks; etc which are difficult to be transported from one place to another, especially if the destination to and from are separated by water. Therefore roll of/roll on ships are designed specifically to solve this very obstacle. The term ‘roll’ is used to imitate the easy loading and unloading feature of these ships. They are also called RORO ships in abbreviated form.

RORO ships are specially designed ships, used to carry wheeled and tracked vehicles like cars, tractors, trucks, cranes as their major cargo load. The modern day RORO ships may even carry tanks, choppers, jets etc. They have their own ramps or use shores ramps to load-unload the vehicles and then carry them from place to place. The cargo usually varies in height and width and hence the below deck and volume utilization is comparatively lesser than other ships and hence can be costlier as well. Hence they are preferred transport for military vehicles and other such specialized jobs.

Various types of RORO vehicles are: ferries, cruise ferries, cargo ships and barges. RORO are classified as Pure car carriers (PCC) and Pure truck car carrier (PTCC).The cargo on RORO ship is measured in unit of lanes in meters (LIMs) instead of the typical metric tons.
The largest RORO ship passenger ferry is MS Color magic which entered the fleet of Color line in 2007 and weighs 75,100GT.It can carry 550 cars and 1270 lane meters of cargo.

The RORO ships are typically economical for short trips rather than the long ones owing to their storage factors and turnaround time. The RORO carriers have a ramp specifically designed to load-unload vehicles as they have wheels which makes the task very easy. These ramps are situated towards the stern/backside of the ship. The disadvantage of such location of ramps is they can cause water tightness if they leak and hence can lead to instability of the carrier due to free surface effect. Such accidents have occurred number of times.
During 1970s these carriers were initially designed as a result of increase in export-import trade of cars. The first Pure Car Carrier was built by Japans K-line in 1973 which carried 4,200 vehicles. The new age of RORO carriers began in 2007, when Wallenius Whihelmsen Logistic designed a large car and truck carrier (LCTC) called Faust.
There are several variations of RORO carriers which are used worldwide:

ROPAX (roll on-roll off passenger): These carriers can carry passengers as well.

ROLO (roll on lift off): Only vehicles can slide off the ramp. For other types of cargoes, crane is mandatory.

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