3. The Docks in Operation

An enclosed dock is one in which the water can be 'impounded' and kept at a constant level. A ship passes from the river through the lock gate into the lock where the water is raised to the level of the water in the dock. When the water level is equal, another lock gate is then opened, allowing the ship to move into the dock.

Some docks, e.g. the London Docks, had a water-filled basin between the river and the main dock. Having entered the basin through lock gates, ships would then pass into the main dock through another set of gates.

Sometimes ships might load or unload in the basin particularly if they wished to get in and out of the dock quickly.

The advantage of an enclosed dock is that loading or unloading can be carried out at any time. A tidal river such as the Thames, which rises and falls up to 20 feet, can make loading and unloading a more difficult operation.

A dock also provides a large area of quayside for ships. Most of the early docks had an import and export dock, as it was convenient to keep import and export work separate.

This was particularly the case when the dock companies had a monopoly on bringing certain goods into the port and wished to maintain strict supervision and control over these valuable commodities.

How an enclosed dock works

West India Docks, 1806