page_title: Chain boat
section_title: Control and navigation
hierarchical_section_title: Chain boat / Control and navigation
caption_attribution_description: Deutsch: Bugansicht mit Kettenausleger des K.B.K.S. No. V, Konstruktion für einen Kartonmodellbaubogen
context_page_description: A chain boat, chain tug or chain-ship was a type of river craft, used in the second half of the 19th century and first half of the 20th century on many European rivers, that made use of a steel chain laid along the riverbed for its propulsion. The chain was hauled by a steam engine mounted on board and enabled the boat to tow a string of barges. In Germany, such a boat was variously referred to as a Kettenschleppschiff, Kettenschlepper, Kettendampfer or Kettenschiff and in France as a toueur.
  The chain was raised out of the water over a boom at the bow of the ship and led over the deck along the ship's axis to the chain engine amidships. The transfer of power from the steam engine to the chain was usually achieved using a drum winch. From there the chain was led over the deck to another boom at the stern and lowered once more into the river. By moving the stern boom and the two rudders, front and aft, from side to side it was possible to replace the chain in the centre of the river again, even when negotiating river bends.
context_section_description: In chain boat navigation the chain was simply laid "loose" on the riverbed for long distances of up to several hundred kilometres. Only the deadweight of the massive chain, which weighed about 15 kilograms per metre (30 lb/yd) or 15 tonnes per kilometre (27 ton/mi), and its natural snagging on the sand and stones of the riverbed provided resistance, so that the chain boat and its attached barges could haul themselves along the chain. The water bore the weight of the boats and barges, whilst the chain only had to cope with the power of the engine. The chain was only anchored at its two ends so that boats could continue to haul themselves to the end of the chain route.
  A problem was caused by sideways displacement of the chain. At bends in the river there was a tendency for the chain, that was laid in a curve, to increasingly pull itself straight and so move towards the inside of the bend. In order to prevent this, chain boats were fitted, fore and aft, with large, powerful rudders. These rudders sometimes had a length of over four metres and were worked with the aid of control wheels on the deck.
  At the bow and stern of the boat the chain was led along a boom that projected well beyond the end of the deck. This prevented the chain from hitting the long rudders. The booms were movable and could be swung sideways using a hand crank. The boat could thereby be oriented at an angle to the direction of the chain. This also improved the chances of replacing the chain back in the centre of the river.
  The boom was also fitted with chain interception equipment so that, in the event of the chain breaking, it would not be able to run away. If the chain catch was not quick enough to hook into the chain, it would simply run away and disappear into the river. It then had to be painstakingly located with a drag anchor and salvaged.
caption: Front view of a chain boat with its boom
exif: {"Image ImageDescription": "Konstruktion eines Kartonmodellbaubogens", "Image Artist": "Michael Bauer", "Image Copyright": "Michael Bauer - f\u00fcr Wikipedia frei"}