The Largest Available Containership, 1970-2015 (in TEUs)
The principle of economies of scale is fundamental to the economics of maritime transportation as the larger the ship, the lower the cost per unit transported. This trend has particularly been apparent in bulk and containerized shipping. For instance, the evolution of containerization, as indicated by the size of the largest available containership, has been a stepwise process. Changes are rather sudden and correspond to the introduction of a new class of containership by a shipping company (Maersk Line tended to be the main early mover), quickly followed by others. The major ship classes include L "Lica" Class (1981; 3,430 TEU), C10 Class (1988; 4,500 TEU), R "Regina" Class (1996; 6,000 TEU), S "Sovereign" Class (1997; 8,000 TEU), E "Emma" Class (2006; 12,500 TEU) and "Triple E" class (2013; 18,000 TEU).
A new class generally takes the name of its first ship. There are some variations concerning how many containers can be carried by a containership depending on the method of calculation. For instance, for the Emma class, a ship could carry about 15,200 TEUs of containers if they were all empty, which represents all the available container slots. If all the carried containers were loaded with an average load of 14 tons per container, then about 11,000 TEUs could be carried (25% less). The official capacity figures used is 12,500 TEUs, which considers that containerships carry a mix of loaded and empty containers, but containerships are usually able to carry slightly more. Thus, container capacity figures should be treated with some caution as they are dependent on the cargo mix and estimated in a conservative fashion.
Since the 1990s, three substantial steps took place in the evolution of containership sizes. The first involved a jump from 4,000 to 8,000 TEUs, effectively moving beyond the "panamax" threshold of around 5,000 TEU. This threshold is particularly important as it indicates the physical capacity of the Panama Canal and thus has for long been an important operational limitation in maritime shipping. Most modern container ports were designed to handle ships of the Panamax class since this standard has been around for a century. Ships of the "C10" class were introduced by APL in 1988 and were the first post-panamax ships with 14 containers across deck with a capacity of 4,500 TEUs (a panamax ship is limited to 13 containers across).
The second step took place in the 2000s to reach the 12,500 TEU level, which is essentially a "suezmax" level, or a "new panamax" class when the extended Panama Canal will come online in 2016. However, this 12,500 TEU capacity is assessed from a ship fully loaded with containers averaging 14 tons. Using a load configuration that includes empties as well can result in effective capacities of 15,200 TEU for a E class ship. From a maritime shipper's perspective, using larger containerships is a straightforward process as it conveys economies of scale and thus lowers costs per TEU carried. From a port terminal perspective, this places intense pressures in terms of infrastructure investments, namely portainers.
A third step is unfolding. In 2011, China Shipping Container Lines took delivery of the first container ships whose theoretical capacities is of 14,100 TEUs, setting a new landmark above the 14,000 threshold. However, the range of ports that can accommodate these ships is limited, so their pendulum service configuration is scheduled along the East Asia - Europe route. Later in 2011, Maersk announced the order of a new generation of 18,000 TEU ships, dubbed "Triple E" vessels, the first delivered in 2013. The 18,000 TEU threshold was overtaken in 2014 when ships of more than 19,000 were introduced. This step is likely to level around 20,000 TEU which is close to the limit of the Strait of Malacca.
Several converging factors underline that further economies of scale in maritime shipping are unlikely to unfold within the foreseeable future, or at least would come at a high cost. The more economies of scale are applied to maritime shipping, the lower the number of ports able to handle such ships which limits commercial options and accessibility. Economies of scale involve higher costs for inland operations as a large quantity of containers arrive at once and must be handled effectively to maintain a level of service. In all the dimensions it involves, economies of scale require capital intensiveness in infrastructure and equipment (ships, portainers, terminal facilities) that is prone to risk. The challenge is no longer about economies of scale, but about finding paying cargo to fill the ships. It is therefore a possibility that the optimal size of a containership would be in the 8,000 to 10,000 TEUs range.