Tankers were first developed in the mid-nineteenth century when ships made of iron allowed liquids to be carried in bulk, economically and without leakage. These vessels, collectively known as tankers, carry a range of liquid cargoes. Cargo capacity of such vessels is measured in Car Equivalent Units (CEU) and the largest car carriers afloat today have a capacity of over 6,000 CEU. These slab-sided vessels feature multiple vehicle decks comprising parking lanes, linked by internal ramps with access to shore provided by one or more loading ramp. The car carrier is the most commonly-used ro-ro vessels. They include vehicle ferries and cargo ships carrying truck trailers. Roll on-Roll off or Ro-Ro vessels come in many forms. Reefer containers need a power source to function and often require inspection during the voyage. Traditional reefer vessels have been largely replaced by the use of reefer containers which are carried aboard container vessels. Cargo is stowed in holds which are then sealed and temperature controlled. Ships designed to carry refrigerated cargo and perishable goods such as fruit or meat are known as “Reefer Vessels”. Large container vessels are restricted by their size to certain ports around the world and are also unable to transit certain areas due to draft or, in the case of canals, beam restrictions. Ultra Large Container Vessels (ULCVs) such as the Emma Maersk (lead ship of the Maersk E-Class vessels) are able to carry approximately 15,000 TEU (depending on container weight). Some small container vessels are geared to allow self-loading and discharging.Ĭontainer vessels are used predominantly on liner routes and are some of the biggest vessels afloat. Containers are usually loaded by specialised cranes or even general purpose cranes with container lifting attachments. Each container is then lashed to the vessel but also to each other to provide integrity. Once the first layers of containers have been loaded and the hatches closed, extra layers are loaded on top of the hatches. There are also longer, taller and even shorter standard sizes, but these are less common.Ĭontainer ships are made up of several holds, each equipped with “cell guides” which allow the containers to slot into place. All standard shipping containers are 8 feet wide and 8 feet 6 inches tall. Standard containers are measured as TEUs (Twenty-foot Equivalent Units) and are generally 20 feet (1 TEU) or 40 feet (2 TEUs) long. They are also used to transport bagged and palletised goods, as well as liquids and refrigerated cargo. Containers can accommodate anything from foodstuffs to electrical equipment to automobiles. A container can be transferred between truck, train and ship relatively easily and is a standard size to simplify transportation. Container VesselsĬontainers have become the main way of transporting manufactured goods around the world. These vessels can also carry loose and irregular cargo, in which case the vessel’s crew and port stevedores pack the cargo to minimise damage and maximise space.Īlthough largely replaced by bulk and container carriers, general cargo vessels still operate throughout the world. There may be specialised handling facilities for such cargo, but usually loading and unloading is carried out using cranes and straps (for boxes) or slings (for bags). General Cargo, known as breakbulk, is usually on pallets or in bags. Smaller vessels can often discharge cargo directly into road vehicles. Cargo is usually unloaded into hopper barges, then transferred by conveyor to silos or open storage. When vessels unload using cranes and grabs, personnel and vehicles are often placed inside the holds to assist the process. Some bulk carriers are geared (usually a crane is located between each hatch) to allow the loading and unloading of cargo at berths without the need for shore equipment.įor unloading, cranes with grabs are the norm, although specialised equipment may be used for certain cargoes. In port, cargo is loaded by conveyor and spouts, or by crane and grab. These vessels are divided into several separate holds covered by hatches. Bulk Carriersįor dry cargoes with a high weight to cost ratio such as coal, grain and ore, economies of scale produced the modern bulk carrier. Such ships sometimes operated a regular service as liners between two or more ports, but could also operate in the “tramp trade” where vessels would go wherever they were required. Cargo would be stowed in different holds and the speed and effectiveness of the loading/unloading process would depend on the the ship’s crew and the port workers or “Stevedores”. Known as general cargo vessels, they would be equipped with their own cargo loading equipment, usually in the form of a derrick lifting device. Historically, dry cargo vessels were the the most common vessels in the world’s merchant fleet.
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