The floating ships of Scharnebeck

Of course not. But what about a ship sailing down the Rhine from Rotterdam to Basel, for example? Basel is 252 metres higher than Rotterdam. So a ship on this route really does have to travel 252 metres uphill. On the return journey, it travels 252 metres back down. You don’t notice this on board, however, because the river has a gentle gradient spread over a long distance. An artificial waterway, on the other hand—a canal—must have no gradient, or it would simply drain away. So the difference in height between different places has to be overcome. This is usually done with locks. Ships enter a lock chamber, the gates are closed, and water flows in or is pumped out. The ship inside is raised or lowered.

Another technical option is a ship lift. Ships leave the canal and enter a water-filled caisson, which is sealed by gates.

The trough and the water in it are then raised or lowered to the next level of the canal. Heavy counterweights and electric motors help with this.

There is a ship lift like this in the municipality of Scharnebeck in Lower Saxony. Its official name is “Lüneburg Ship Lift”, because Scharnebeck is near the city of Lüneburg. It is part of the Elbe Lateral Canal. This ship lift overcomes a height difference of 38 metres.

The Elbe Lateral Canal connects the Mittelland Canal with the Elbe. It starts near Wolfsburg and ends at the town of Atlenburg. The Scharnebeck ship lift was commissioned in 1975. It consists of two troughs, each with four towers housing the machinery. Each trough is 100 meters long, 11.8 meters wide and 3.38 meters deep.

When filled with water, one of these troughs weighs 5,800 tonnes. Each trough is held up by 240 steel cables, each 54 millimetres thick. The counterweights are made of heavy concrete discs and weigh 5,936 tonnes altogether. This makes them 136 tonnes heavier than a filled trough.

Four small electric motors are enough to move the difference in weight. Incidentally, when a ship enters, the weight of a caisson does not change, because each ship displaces as much water as it weighs. It takes about 3 minutes to move a caisson up or down. The entire journey, from entering to leaving, takes around 15 to 20 minutes.