A Little History of the Container Vessel
If you have read our article on container types and sizes, then you know that the first container vessel was actually a modified tanker vessel (more below), the Ideal X, which journeyed from New Ark, New Jersey to Houston, Texas on April 26, 1955. It carried just under 60 containers - 35-foot trailers with removed chassis.
Today, the largest containerships can carry well over 20,000 twenty-foot equivalent units (TEUs). A 20-foot container measures 1 TEU, a 40-foot container measures 2 TEU, meaning that large containerships carry thousands of containers. The technical progress and size growth that containerships have experienced is astonishing.
The ability to load more cargo onto one single ship increases efficiency and thus reduces carbon emissions. The popularity of the containership is due to the multi-modal quality of the standard ISO container, which can be loaded onto trucks, barges or transported by rail.
Modern containerships have their holds (the space where the cargo is stored) divided into bays with cell guides (they are also referred to as cellular ships) in which the crane operators can snugly fit the 20- and 40-foot containers. This enables efficient, speedy loading. Every deep-sea container’s hold is capped with a hatch cover, which benefits both the stability and safety of the ship.
Container vessels vary by many sizes and design elements in order to host special equipment and commodities such as reefer containers or hazardous cargo, but it is worth mentioning that some may be equipped with cranes. Such ships are referred to as geared (as opposed to gearless ships, which do not feature a crane) or as lift-on/lift-off (LoLo). While this means that these vessels can visit ports that do not offer cranes, those are becoming rarer – and so are LoLo containerships.
The way the supra structure of the ports developed enables fast and easy loading of the containerships today. Tide, water depth and size of port basins, availability of pilots & tug boats, size & reach of (gentry) cranes, availability of van carriers or reach stackers, hinterland connectivity (road, rail & waterways), customs facilities – they all work in conjunction to make container shipping happen.
Containership sizes are often ranked by their TEU capacity, ranging from a few hundred TEUs for feeder vessels “Feeder and Barges” to 18,000 TEUs or more for Ultra-Large Container Vessels (UCLVs) “Panamax, and Other Straits”.
Size matters because the ability to load more containers onto the ship is key to efficiency, but that is not all. Being able to operate in certain port terminals or being able to navigate through the Panama or Suez canals are just as defining a factor for efficient seaborne cargo transportation.
Feeders and Barges
Feeder vessels have a capacity ranging from 300 to a maximum of 1,000 TEUs. They can operate in smaller ports that large sized container vessels cannot berth at. Their will feed cargo to these large ships – referred to as mother vessels – in deep-sea hubs and transport cargo from the large vessels back to shore. Strong coordination saves time and enables the larger vessels to cover a reduced number of ports. Feeder vessels can be geared or gearless.
While they do not qualify as feeder vessels, container-carrying barges are used to transport containerized cargo through inland waterways that bigger vessels can also not enter. In this type of intermodal transport, the barge can carry up to 300 TEUs in Europe, while in North America they can range 450-900 TEUs.
Similarly, vessels operating on the Saint Lawrence Strait are limited in capacity due to draught limitation, but they are not feeders. They are specialized ships that require an “ice-class“, which enables them to operate throughout the year – even through a massive ice drift.