Bertha the Dredger
Road traffic at the dock was facilitated by a bascule bridge, again believed
to be of a Brunel design, and this is the bridge over which traffic still
goes today. Completing Brunel’s contribution to the dock’s infrastructure
was the dredger, Bertha. The main problem for the dock operators
was heavy silting. Bertha, the steam-driven dredger, was designed
such that she would run up and down a chain from one end of the dock to
the other. At the end of each journey, the chain would be moved a bit further
across the end of the dock, so that over a period of several trips, she
had covered the entire dock basin. Imagine if the dock were drained and
a bulldozer was used to push the silt deposit to one end of the dock. The
bulldozer blade is down in one direction and up in the other. That was
how Bertha worked, but under the water.
Text Copyright © 2008 Roger Evans

