Earliest Times
Early ships whether for passengers or cargo were generally flat bottomed and would be ‘beached’ to unload and load. Loading was done by hand, limiting what could be carried aboard. Ships could be specially built to carry heavier loads, for example, large carved stones for stone circles – Stonehenge etc. From the earliest times, through to the Romans and into the 17th century this was the main mode of loading and unloading.
First Liverpool Dock
From the 17th century it was recognised that to get ships loaded and unloaded it would be necessary to create areas where ships could unload 24 hours a day and be made more efficient. Liverpool’s first dock can still be seen below Liverpool 1. This also meant that size would be critical but since ships were built of wood the size limit was set anyway. Wooden ships would reach their maximum sizes in the 19th century with the great Line-of-Battle ships which were less than 100 metres long and generally around 75 metres.
With a deep basin and a lock gate to keep the water in the dock and a stream to supply the dock with water to maintain the depth within the dock Liverpool’s dock enabled work on ships throughout the day with access directly to the river. Liverpool’s dock followed that of London but made a huge difference to trade. Ultimately Liverpool docks expanded as new docks, with locks, were created as the riverside shown below was reclaimed.
The General Cargo ship
In the late 19th century and early in the 20th century the sailing cargo ship was replaced by a sailing ship with auxiliary engines with an arrangement of holds and hatches which remained with such ships for around a century.
Above is a typical cargo ship of the late 19th early 20th century. It has a central island including the bridge and engines with cargo holds before and abaft of the central island. There are two large masts with derricks to load and unload cargo but the spars and sails of the earlier sailing ships have disappeared. Below is basically the same ship, this time post WW2, with a greater number of heavy posts with derricks for loading.
The general cargo ship was a standard through from the end of the 19th century through the 20th century with little change in the island arrangement.
After WW2 the general design changed and the main island was aft creating a large cargo area forward of this island with the posts and derricks concentrated in this area. This was a more economical arrangement and all cargo vessels tended to be built with the bridge and accommodation aft. Although the vision for the officers on the bridge was not as good, the improvement of electronic navigational aids and radar made it more sensible.
The Container Ship
The container ship began to be seen later in the 20th century and by the 21st century had become the most common form of cargo carrier.
These colossal vessels, many over 300 metres in length, carry up to 17,000 standard sized containers. Loading and unloading requires special cranes and the whole operation has to be controlled by computer. The cranes are designed to operate in tidal areas which means large docks with locks are unnecessary. Tracking what is in each container and the weight of each container is essential as an empty container looks just the same as a full one. Loading the containers has to take account of the order in which they must be unloaded and the position in which they must be placed on the ship to ensure stability.
Roll-on Roll-off Cargo Ships
Such ships as these will carry a mixture of different cargos. Containers are often part of the cargo but these ships take rolling cargo – articulated lorries, large vehicles and vehicles which will not fit into a standard container. To load, the ship requires a dock with locks so that vehicles can drive straight on but also the container cranes to load containers. In Liverpool, the new ships using the RoRo facilities had to be built so that they would be able to enter the locks, with a tug.
Atlantic Sail is such a ship operating from Liverpool 2 container port and Gladstone dock.
Barrels to Bulk Carriers
Packaging cargo was never easy. For some centuries the barrel was the main storage container for commodities such as salted meats, spices and other smaller items as well as water and oil. Materials such as coal and grain could be carried in 50 kg bags which made them easier to load. Many will remember the coalman delivering coal in large sacks to domestic homes. Ships could carry coal loose in the hold of a ship, though this could be dangerous due to spontaneous combustion. Oil and grains such as rice were transported in bags, generally though they could easily be damaged if water got into the ships as was common in wooden vessels.
Towards the end of the 19th century special ships were built to carry such cargos. Grain carriers and tankers became a common sight in rivers with their special facilities. The grain silos in Gladstone dock Liverpool and Tranmere oil terminal are familiar to us. Oil is a dangerous cargo and many wooden ships disappeared without trace while carrying such cargos in barrels. The oil tanker, the largest of the bulk carriers have been up to 450 metres long being able to carry 500,000 tons of oil, a cargo almost as valuable as the ship itself. Loading and unloading is easy with these special facilities. Even scrap metal, coal, cars and woodchip may now be transported in specially built bulk carriers with their own special facilities or means of unloading.
What cannot be transported in this way may be put into a container. There will always be a ship which can be adapted to take any cargo – giant cranes from China for Liverpool 2 container port – or barges to carry the wings of aircraft for the aircraft industry in Europe.
These bulk carriers are now responsible for the majority of cargos travelling around the world.