Six Generations of Containerships

Since the beginning of containerization in the mid 1950s, containerships undertook six general waves of changes, each representing a generation of containership:

The first generation of containerships was composed of modified bulk vessels or tankers that could transport up 1,000 TEUs. The first containership, the "Ideal-X" was a converted World War II T2 tanker The container was at the beginning of the 1960s an unproven transport technology and reconverting existing ships proved out to be the least expensive and risky solution. These ships were carrying onboard cranes since most port terminals were not equipped to handle containers and were relatively slow, with speeds of about 18 to 20 knots.
Once the container began to be massively adopted at the beginning of the 1970s, the construction of the first cellular containerships (second generation) entirely dedicated for handling containers started. All containerships are composed of cells lodging containers in stacks of different height depending on the ship capacity. Cranes were removed from the ship design so that more containers could be carried. The ability of ports to handle containership ceased to be a major concern with the setting of specialized container terminals around the world. These ships were also much faster with speeds of 20-24 knots that would become the speed of reference in containerized shipping.
Economies of scale rapidly pushed for the construction of larger containerships in the 1980s. The larger the number of containers being carried the lower the costs per TEU. The process became a virtuous circle compounding larger volumes and lower costs. The size limit of the Panama Canal, which came to be known as the panamax standard, was achieved in 1985 with a capacity of about 4,000 TEUs (third generation). Once this limit was achieved, we have to wait about a decade to see a commitment to a new generation of containerships. The APL C10 class containerships were introduced in 1988 and are the first containerships the exceeded the 32.2 m width limit of the Panama Canal. At the same time panamax container ship designs were evolving to take maximum advantage of the limitation in beam.
By 1996 full fledged fourth generation of containerships were introduced and capacities reached 6,600 TEUs. This represented a market risk since a ship above the panamax size required a substantial amount of cargo to be used and by the late 1990s the rapid growth of global trade made such a ship class a marketable proposition.
Once the panamax threshold was breached, ship size quickly went to the fifth generation (Post Panamax Plus) with capacities reaching 8,000 TEUs ("S Class"). Going beyond panamax was perceived as a risk in terms of the configuration of the networks, additional handling infrastructure as well as draft limitations at ports. Each subsequent generation of containership is facing a shrinking number of harbors able to handle them. Containerships above the third generation require deep water ports (at least 43 feet of draft) and highly efficient, but costly, transshipment infrastructures.
By 2006, sixth generation containerships came online when the maritime shipper Maersk introduced a new class having a capacity in the range of 11,000 to 14,500 TEUs, the Emma Maersk, (E Class). This generation will take two specifications. The first will take the shape of "New Panamax", with ships designed to fit exactly in the locks of the expanded Panama Canal, expected to open in 2014, and which confers capacity of up to 12,500 TEU. The second can be dubbed "Post New Panamax" since these ships are bigger than the expanded Panama Canal specifications and can handle up to about 18,000 TEU (Triple E Class). It remains to be seen which routes and ports these ships would service, but they are limited.

Containership speeds have peaked to an average of 20 to 25 knots and it is unlikely that speeds will increase due to energy consumption. The deployment of a class of fast containerships has remained on the drawing boards because the speed advantages they would confer would not compensate for the much higher shipping costs. Supply chains have simply been synchronized with container shipping speeds. Although economies of scale would favor the construction of larger containerships, there are operational limitations to deploy ships bigger than 8,000 TEU. Containerships in the range of 5,500 to 6,500 TEU appear to be the most flexible in terms of number of port calls since using larger ships along trade routes would require fewer calls and thus be less convenient to service specific markets.