Photo: Dr. Jean-Paul Rodrigue, 2012.
Stacking containers on a ship is a complex operation involving a close interaction between the container yard, drayage operations between the ship and the yard and crane operations. The above photo depicts a typical stacking configuration of different container sizes and types taking place on a Panamax containership (13 container rows) at the port of Veracruz in Mexico (ICAVE terminal operated by HPH). Each row (more likely several rows) generally contains containers bound to a specific port. This is done to facilitate crane operations since cranes are designed to quickly move along a row but it requires the entire crane to be displaced laterally to access another row. Since a ship is usually serviced by several cranes, they can all operate at once on their ship section without impeding one another. This also enables a distribution of the weight across several sections of the ship. The empty rows are likely to be loaded at another port of call (again, rows are usually port specific). 20 foot and 40 foot containers are usually loaded in separate rows to facilitate staking and loading/unloading efficiency. Container loads bound for a single large customer are usually bundled together, as evidenced by the 20 foot tank containers on the above photo (the boxes with white and silver circles). Specialized and oversized containers are stacked on top of the pile since their structure forbids the stacking of container on top of them. In this case top loaded containers are used to carry oversized cargo, with some of them covered with a tarpaulin. Less visible are reefer containers stacked separately (in white).