Trans RINA, Vol 152, Part A2, Intl J Maritime Eng, Apr-Jun 2010


containerised by the mid 1970s. Since then the 3000 TEU (twenty foot equivalent unit) ship has grown to 14,000TEU, although speeds have remained in the mid 20s knots. Following oil


price increases, the steam


turbine container ships of around 80,000shp (60MW) of the early 1970s gave way to slow speed diesel ships, with engines now available with up to 115,000bhp (85MW) with 14 cylinders on a single screw of around 10m diameter.


There had been great expectations from barge carriers from the late 1960s, with lift-on/lift off concepts like the 380dwt LASH (Lighter Aboard SHip) barge and even a few float-on/float-off designs. While loading or discharging the mother ship could be done in hours, the cargo still needed handling to and from the barge itself, perhaps at an upriver berth. But the mainly low value commodities that could move in 380-ton parcels could not support the high costs of the operation, so by the late 1980s nearly all barge carriers had been converted or scrapped.


Figure 12. Standardisation of container dimensions and fittings in 1965 enabled the widespread adoption of containerisation, slashing port


ships so permitting much larger ships. The deck stow roughly doubled the number of containers carried in the holds. Until the 1980s, such ships were designed to the limits of the locks of the Panama Canal (built in 1914), corresponding to about 4600TEU (twenty foot equivalent units), the size of Dusseldorf Express seen leaving Miraflores Locks. Ships of three times that capacity are now in service, which will be able to transit the third set of locks due to open in 2014.


It was in the 1950s that the use of turbocharging in 2- stroke diesels (previously in 4-strokes), heavy fuel oil and cylinder bores approaching 1000mm enabled the slow speed direct drive engine to challenge the steam turbine in bigger ships. That remains the prime mover of choice today, although the emphasis is now on reducing emissions which require higher quality fuel. Medium speed diesels had been developed between the wars (sometimes based on submarine or locomotive diesels), and post-war were widely favoured in smaller vessels and in low headroom ships like ferries, usually geared rather than direct drive.


The short sea roll-on/roll-off vessel evolved from the Second World War tank landing ships in the 1950s. They offered big reductions in port time where trailers could be used, as well as providing a drive-on/drive-off facility for cars and trucks. These required innovation in cargo access equipment, with external and internal ramps and elevators. The same concept was applied to deep sea ro- ros in the late 1960s carrying cargoes such as forest products and containers, block stowed on the decks or on trailers. But after two decades of competition, the cellular container ship won out, partly by being better suited to


time for general cargo


Post WW2 deep sea passenger vessels continued to be built in significant numbers. Innovations such as stabilisers and later bow thrusters made for a more comfortable voyage and easier manoeuvring. Bulbous bows were often fitted, tuned to their relatively high Froude number and near constant draft – later bulb shapes were developed for a much wider range of hull forms and drafts. Aluminium superstructures were introduced in the mid 1950s, which allowed an extra deck to be fitted without jeopardising stability, as well as doing away with troublesome expansion joints. But long distance passenger sea transport had been overtaken by air transport by the late 1950s, so by the late 1960s all the large liners had been scrapped or converted to cruising or become museum ships, as Queen Mary at Long Beach in 1968. But


as that door closed, another opened, the


purpose built cruise ship (not ‘cruise liner’, as they do not operate on a fixed route). Pioneered by Scandinavian owners, ever larger and more luxurious floating leisure centres developed into today’s 150,000gt plus monsters carrying over 4000 passengers – the 200,000gt/6000-pax barrier was broken in 2009. Technical problems requiring solution included structural


integrity and safety with


large open spaces like atriums, hotel electrical loads comparable with propulsion loads leading to diesel- electric systems, multiple thrusters (including stern as well as bow) and podded propulsors, improved fire protection, lifesaving appliances and subdivision.


the hub-feeder concept, with large mainline ships serving major ports like Rotterdam supplied by smaller feeder container ships from secondary ports.


Figure 13. .Spanning almost the entire century and a half, high speed catamaran Normandie Express passes preserved ironclad Warrior (right)


2008. Both are about 6000tons gross. Warrior was built in 1860, iron hull, 5470 ihp steam


at Portsmouth in reciprocating


machinery with single screw, 14 knots and rendered A - 58 ©2010: The Royal Institution of Naval Architects


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