As barge cruise aficionados know, the canal system is an intricate and carefully balanced feat of engineering. The keystone that supports these waterways is the lock. Whether run by a lockkeeper, actioned by barge owners, or controlled automatically by computers, locks enable a barge cruise to move quickly and easily through the countryside. Without this engineering marvel, canal travel would be completely impossible. So, how was the lock invented and what exactly does it do?
When and Why Were They Invented
Rivers have long served as essential networks of trade and communication. However, these networks were limited as boats could not travel far inland and it was very difficult to travel uphill via river. Locks, an invention which permitted boats to gain or lose height, were developed by the Chinese in the tenth century and by the Dutch in the thirteenth. The early “pound” lock focussed on the filling and draining of a small vessel-sized chamber, and facilitated the construction the first independent waterways – or canals – which led to the expansion of trade across the globe. This arrangement also helped vessels travel up or down stream on tamed rivers such as the Thames.
This centuries-old invention is used to this day on some of the most important global trade routes – the Panama Canal, for example – as well as enabling more leisurely travel, such as a barge cruise.
How Do They Work?
As we know, these technical wonders are designed to help boats go either upstream or downstream. If a vessel wants to travel upstream, first the bottom sluices must be opened up allowing the lock to drain. Next, the lower doors are opened, and the boat can move into the chamber. After the lower doors and bottom sluice gates close, the top sluice gates are opened, the water rushes in and the water level rises. The boat is gently raised to the next level and the top doors can be safely opened, allowing the boat to continue its journey. On the return the same process happens, but in reverse.
Getting Technical: Flights and Staircases
Engineers working with canals frequently have to tackle sudden changes in height. These often cannot be dealt with in a single lock, leading to a common feature of canals called a ‘flight’. This term refers to a group of up to 30 locks placed close together, but with a large gap in between allowing boats to pass each other. They gradually raise or lower barges to the appropriate level. As each individual chamber uses the water from the one above, a flight uses the same amount of water as a single lock.
A more popular arrangement is the staircase; here the top gates of one chamber act as the bottom gates of the one above. To aid this process, a side pond is used to perfectly regulate the levels in the top and bottom chambers. Of course, the best way to appreciate these astounding feats of engineering is from the comfortable deck of a gentle barge cruise.
Paul Newman is the Marketing and E-Systems Executive for European Waterways, the UK's most respected provider of all-inclusive, luxury barge cruise itineraries in France and other great destinations. Part of a team of experienced barging aficionados, Paul is first in line to endorse the perks of a slow-paced barge cruise to anyone looking for a unique holiday experience.