One of the wonderful things that shipping has given us is the Roll-On Roll-Off or RORO ship. The RORO ship is probably an adaption of the landing ships of the Second World War, built with a bow ramp and to beach thus allowing military vehicles and logistics on wheels to be carried over large distances and quickly discharged ashore. In its simplest form the RORO ship takes the form of a double ended ferry with ramps at both ends and a deck to carry vehicles on – there were many of these operating in Malaysia – many of the larger rivers in the more remote places had to be crossed in this manner as bridges had not been built. The Penang ferry is another example of a simple RORO vessel and it is this form that perhaps the first commercial RORO Ships took shape in 1953 (the same year the first commercial jet-liner, the De Havilland Comet, was introduced), allowing a “drive-on” service to be introduced from Dover to Calais. This eliminated the need to load vehicles by lifting gear which was a time consuming and delicate affair, thus allowing a ten-fold increase in the throughput of cars on the crossing. The idea was extended first to the carriage of freight in trucks and trailers – allowing door-to-door delivery of goods, particularly refrigerated goods without having the need to unload and reload them into road freight vehicles. In the 1970s, as demand for passenger cars increased tremendously – particularly from Japan, dedicated Pure-Car Carriers (PCC) were introduced to transport brand new cars across the globe.
A feature of the modern RORO ship is the huge garage contained within the steel structure of the ship, often with several decks accessible through ramps and sometimes lifts. The garages are also equipped with huge ventilation fans, meant to extract exhaust and fuel fumes to keep the decks safe. “Safe” I guess in this case a relative term, as the vehicle decks of a RORO ship would probably count as one of the more dangerous places to be hanging out in – not that this is usually permitted. Standing in the middle of one gives the impression of being in a huge car-park, which a RORO deck effectively is, only that it is built of steel instead of concrete, and of course that vehicles are packed very tightly with barely any space left in between, as the “car-park” fills-up. It is a place where life is literally lived on the fast lane, with trailers, and sometimes trucks and cars zipping up and down and in a loading or discharging frenzy that is very much motivated by by the rush to load or discharge vehicles in the shortest possible time.
On the larger RORO ships, ramps are a common feature – most modern ROROs with multiple vehicle decks are fitted with hoistable ramps which can be hoisted up to the deck, allowing the space on the ramp – as well as below it to be utilised – maximising the use of deck space. This is opposed to fixed ramps, which are cheaper to build but result in valuable deck space being sacrificed. On some other RORO ships, movable decks can be lowered in place, allowing intermediate decks to be quickly created allowing two or more decks of vehicles requiring a lower headroom (such as passenger cars) to be utilised in a space that can also be used to carry on deck of cargo requiring a larger headroom.
Safety from a ship stability viewpoint has been of prime concern on RORO ships with its large decks which if flooded with water not only reduces buoyancy but also results in a large free-surface, since the well documented and published capsizing of the MS Estonia. Besides maintaining watertight integrity of the decks through which vehicles are brought on the ship generally through a stern or bow ramp, calculations are now required to demonstrate that these ships are safe even with the decks flooded with water.