The Largest Available Containership, 1970-2008 (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), R "Regina" Class (1996; 6,000 TEU), S "Sovereign" Class (1997; 8,000 TEU), and E "Emma" Class (2006; 12,500 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 15,000 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 able to carry slightly more. Thus, container capacity figures should be treated with some caution as they are dependent on the cargo mix.

Since the 1990s, two substantial steps took place. 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. The second step took place in the 2000s to reach the 12,500 TEU level. This is essentially a "suezmax" level, or a "new panamax" class when the extended Panama Canal is expected to come online in 2014. 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. Thus, the matter of scale is bringing forward a paradox as the more economies of scale are applied to maritime shipping, the lower the number of ports able to handle such ships.