Chain boat
[2][6][7] The chain was engaged using a steam engine mounted on board and enabled the boat to tow a string of barges.
[2][6][8][9] In Germany, such a boat was variously referred to as a Kettenschleppschiff, Kettenschlepper, Kettendampfer or Kettenschiff and in France as a toueur.
[7] Chain boat navigation revolutionised inland shipping during the Industrial Revolution in the second half of the 19th century in Europe and superseded the hitherto commonplace haulage of barges by draught animals or people.
But by the first half of the 20th century they were increasingly threatened by competition from ever more powerful paddle steamers, something that was aided by the canalization of rivers.
[11] The first designs and early technical stages in the development of chain boats took place in the mid-19th century, especially in France.
The prototype of all later chain boats on the rivers Elbe, Neckar and Main was the French steamboat La Ville de Sens, which was built by the German engineer, M Dietz, around 1850 in Bordeaux and plied the upper Seine between Paris and Montereau.
Its technically very advanced operating principle and its engineering features were adopted by all the later European chain steamers.
This deck shape - low at the bow and stern, and higher in the centre - is typical of all subsequently built chain boats.
The water bore the weight of the boats and barges, whilst the chain only had to cope with the power of the engine.
In order to prevent this, chain boats were fitted, fore and aft, with large, powerful rudders.
In fast-flowing currents or when there were problems lifting the chain due to silting or obstacles on the riverbed such as large rocks, the boat could swing off-course markedly and list to one side.
It has been calculated that even if the chain links wore down to half their original cross-section, this force would not have led to a break.
This could produce tensions both on the drums and between them that were so large that the chain links could not withstand the tensile load and their fracture limit was exceeded.
[19] As a result, there was a continual movement of the chain, that made control more difficult in more dangerous sections of the river, such as rapids.
[19] Its inventor, de Bovet, developed a technique to increase the friction on the transmission drum by magnetic force.
The engagement of the chain on the traction drum was achieved by magnetic force created by electromagnets that were built into it.
In addition to faster downstream travel times, the auxiliary engine also enabled steering corrections during chain operations and simplified turning manoeuvres.
The outflowing jets of water propelled the boat forwards (upper diagram of the elevation view).
[23][24] These second generation chain steamers were equipped with two of these water turbines, which were found on the port and starboard sides.
[25] During a turning manoeuvre the water flowed forwards on one side and backwards on the other in order to rotate the boat.
[26] They therefore had large, side-mounted paddle wheels as auxiliary propulsion for the downstream journey which were driven by engines with a rating of 300–400 hp.
[27] This type of auxiliary system was used by some craft on the Danube for downstream journeys in order to enable barges to be towed in that direction as well.
