We live in a world of specialisation, in which many ship types are designed to fulfil a single function, perhaps – like LNG carriers or very large container ships – carrying only the cargo for which they were designed. But there are some ships which have been built to be the ultimate in flexibility and are able to carry a wide range of cargoes, their owners having shrewdly calculated that there is sufficient demand for these versatile units to justify their construction.
Among these may be found a number of deep sea Ro/Ro ships, which cater both for cargo in containers and the large number of cargo units that may be too large or too heavy to fit into the conventional box. It is the boast of the operators of these ships that if a cargo can be fitted with wheels and rolled, it can be rolled onto the gigantic ramps of their ships and into their capacious freight decks. Regardless of weight or dimensions, the cargo can be carried.
A regular stream of publicity pictures tells of the quite astonishing loads that are carried around the world in these ships. Enormous earth-moving equipment is rolled over their massive ramps, as are the fuselages and separate wings of sizeable aircraft. Helicopters and large yachts attract the attention of the dockside photographers, along with pressure vessels of great length. Indivisible loads of various kinds, which would be either impossible or too costly to break down into smaller elements, are frequently seen on these vessels, which will also tend to carry export vehicles, caravans and mobile homes in large quantities in their vehicle decks. Entire railroads have been modernised with engines and wagons filling the cargo spaces of these capacious ships and delivered without fuss.
These very large, multi-decked Ro/Ro ships will compete for the heavy or “awkward” cargo with a fleet of conventional cargo ships equipped with heavy lift cranes that will lift, rather than roll these difficult cargoes aboard. Project cargo consisting of heavy refinery plant, enormous cranes, and other difficult cargo such as wind turbine components or offshore equipment will tend to be carried in this fashion.
A third type of specialist heavy lifter will compete for the really heavy or difficult units, such as assembled container cranes and gantries or heavy floating plant, such as dredgers or drilling rigs. Once all such units would have to be broken down into units that would fit through the hatches of conventional cargo ships, or carried as deck cargo. These “carry everything” ships also fulfil a useful service in facilitating trade in so many different ways, making it feasible to order machinery at a reasonable cost, from the other side of the world.