page_title: Schwimmtor
section_title: The Schwimmtor
hierarchical_section_title: Schwimmtor / The Schwimmtor
caption_attribution_description: Wien, Sperrschiff, 1873
context_page_description: The Schwimmtor, also known as the Sperrschiff, was a floating barrier designed to protect the areas along the Donaukanal in Vienna from flooding and ice. It was built by Wilhelm von Engerth, entered service on 13 December 1873, and was scrapped following World War II.
context_section_description: The Schwimmtor was a symmetrical-shaped barge without any means of propulsion. It could only be brought into place by means of man-powered winches and the natural current of the canal. Wilhelm von Engerth had not approved the construction of a steam-powered winch because it would have been too expensive.
  The Schwimmtor was produced in the John Cockerill’s steel factory in Seraing (Belgium) under the Austrian chief engineer J. Ritter von Kraft. It was assembled in the shipyard in Linz (Upper Austria).
  Measurements:
  Length: 48.6 metres
  Width in the middle: 9.5 metres
  Width at the tips: 1.0 metres
  Height: 5.7 metres
  Weight: 440 tonnes
  The Schwimmtor was coated with steel sheets on its sides and on the bottom. These were 10-12 millimetres thick and riveted in place.
  Additional features of the Schwimmtor:
  Boiler with 30 m² heated surface
  Two centrifugal pumps (each of which could shift 165 cubic metres of water per hour)
  Two manual pumps
  A manual device for loading ballast (which could load 1000 stones per hour or unload 600 stones per hour)
  Steam heating, which was designed to prevent the valves and pipes connecting the pumps from freezing.
  2000 kilograms of cast iron were kept on board as ballast. Up to 1200 granite stone blocks weighing 17.5 kilograms each could also be loaded as required. The Schwimmtor’s water tanks could also be flooded to make the barrier sit deeper in the water.
  The decision to employ the Schwimmtor depended on the level of the water at the Ferdinandsbrücke (today the Schwedenbrücke). When the Danube flooded, ballast was loaded onto the barrier to make it sit deeper in the water, although it was essential that it never completely blocked the flow of the canal. The amount of ballast on board therefore had to be constantly adjusted as the level of the water in the Danube rose and fell.
  In order to guard against ice being driven downstream in winter, it was sufficient to place the barrier across the surface of the canal. The Schwimmtor’s straight sides meant that very little ice was pushed beneath it. It was however important that the barrier could rise and fall with the level of water in the canal.
  The Schwimmtor was later fitted out with “ice needles”. These were steel spikes that could be attached to the sides of the barrier. They reached to the bottom of the canal and served to catch ice chunks before these could pass underneath the blockade.
caption: The Schwimmtor in 1873
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