Chain boat navigation

The chain shipping ( often referred to by the generic term Tauerei ) was a form of towage and was applied in the second half of the 19th and in the first half of the 20th century at several European rivers. It revolutionized navigation on rivers so far as a single driven by a steam engine chain tug many unpowered barges - so-called barges - could pull cost. The chain was attached from amidships on the deck and pulled by the steam engine driven chain drums on the ship, the chain was lifted over the bow out of the water, ran across the deck of the steamer and sank back again in the river. The chain was continuous, following the meandering river, in the middle of the river. Many of the time not straightened rivers were characterized by strong currents and shallow depth, what paddle steamers were less suitable.

The chain began shipping on the Seine in France and on the Elbe in Germany, but they also took place on other rivers such as the Neckar, the Main and the Saale. Initially drove the chain ships also down valley to the chain. Because of the time-consuming and complicated intersection maneuvers between mountain and valley moving ships the chain tugs but were soon equipped with an additional auxiliary drive to drive regardless of the chain to the valley.

  • 2.1 France
  • 2.2 Belgium
  • 2.3 German Empire and Empire of Austria 2.3.1 Elbe and Saale
  • 2.3.2 Danube
  • 2.3.3 Brahe
  • 2.3.4 Neckar
  • 2.3.5 Havel and Spree
  • 2.3.6 Main
  • 3.1 chain tug
  • 3.2 chain
  • 3.3 encounter between mountain and downhill driving chain vessels
  • 3.4 Experiments with an endless chain
  • 5.1 flow and flow velocity
  • 5.2 Water Depth
  • 5.3 Investment costs
  • 5.4 flexibility

Historical Development

Technical precursors before the 19th century

The goods transport on the river was in the time before the chain shipping limited to timber ships without own drive. Downstream allowed to drive the boat or used sail with the wind force. Upriver attracted people and / or animals from the shore the boats on long ropes, which is called towing. In shallow waters, the boats could be moved upstream by Punting ( pushing off the boat from the river bottom by means of long poles ). Where a towing the bank has not been possible, a movement has been practiced, also referred to as " warping ". These power sections could be overcome by above the point in question anchored a rope on which the crew moved upstream on their boat.

The Italian engineer Jacopo Mariano revealed in a manuscript from the year 1438, a figure with the basic idea of the later chain shipping. The ship runs on a longitudinally laid rope in the river upstream. The rope is wrapped around a central shaft that is driven by two lateral water wheels (see figure above ). Behind the ship is a small ship -like body, which is detected by the current, holding the rope taut and so provides the necessary friction on the shaft.

Fausto Veranzio described around 1595 a system of rope sailing, allowed greater speed and also without any additional driving machine. Two boats are connected to a rope which is passed over a fixed in the river anchored pulley. The downstream -propelled small boat drifts very quickly through the large, attached on both sides water sail and thus attracts the larger boat against the stream uphill. The large cargo ship in the picture has two side water wheels, which in addition to coil the rope and thus increase the speed. However, it is not know to what extent the system also practical was used.

1723 described the later Electorate of Commerce Marperger a proposal of the Mathematics professor Nicolaus Molwitz from Magdeburg to use a mechanical aid to overcome the rapid waterfall under the Magdeburg bridges. Until then, probably 50 men for overcoming this section of the river were necessary. The idea was to build a "machine" with two horizontal shafts, the rope should be handled in such a way to the front shaft that this is always handled by the front wave and wind up on the rear shaft. The additional use of levers, it should be possible after Marperger to make do with five or six men for the ship's passage. But same time it emphasizes that the machine indeed " given ", but never " come to use " was. Due to the parts of the description of this basic principle seems to be similar to the structure of subsequent chain ships. This section of the river was later also the starting point for the first chain ships in Germany.

The first practical experiments with a rope ship there in 1732 at the instigation of standing in the French service Marshal Maurice of Saxony. This took place near Strasbourg on the Rhine. Three pairs of drums having different diameters were placed on a rotatably mounted to and driven by two horses vertical axis. The rope was depending on the required force moves by wrapping one of the pairs of drums, while the other two pairs of drums mitliefen free. This variable ratio allowing a better utilization of the force. Compared with the towing of country doubled for the same number of horses inserted the forward moving load.

Attempts in the first half of the 19th century

In 1820, there were in France several inventors who deal with the technical implementation of the drive ships with ropes or chains. This also included the engineers Tourasse and Courteaut their attempts on the Saône in Lyon. They attached a 1 km long pull rope made ​​of hemp on the shore. This was wound on a drum located on the ship and the ship so drawn forward. Six horses were responsible for the movement of the drum.

With the progressive industrialization in the 19th century, the demand increased significantly for transport capacities on the waterways. However, the industrialization also revolutionized the transport system itself with the steam engine the first engine for an independent drive of the ships was available. However, the first steam engine was still relatively low, while their weight was also very high. So they looked for ways to most effectively implement the force in a movement of the ship.

Somewhat later led the two engineers Tourasse and Courteaut on the Rhone between Lyon and givors attempts by using the steam power. Which runs on a steam ship transported accompanying the 1000 meters long hemp rope up the river and anchored it here on land. After that, the escort ship went back and brought the lower free end of the rope to the actual Tauer. This pulled the rope up the river, and gave it the rope while the train back to the drum of the escort ship from. During this procedure, launched a second escort vessel, rushed up the river, there to anchor a second rope and so to save waiting time.

Vinochon de Quémont replaced in experiments on the Seine, the rope by a chain. The results of the first tests is in the yearbook of the inventions of 1866 to read: Wiewol in all these [ previous ] Try not continuous chain came into use, but the pull chain a piece had always anew be managed along by a boat before the ship could be set in motion, yet the results published so satisfactory that already in 1825 a society was formed under the leadership of Edouard de Rigny for driving the Seine on the route Paris to Rouen this systems. The introduction of the " entreprise de remorquage " but failed due to faulty design. The chain steamer " La Dauphine" was not built according to the instructions of Tourasse. The draft of the ship was too big and the machine too weak. In addition, the winds were too far back on the deck. But the financial strength of the company was too small.

1826 tested M. F. Bourdon, a variant with two steam ships. One of the ships went ahead driven by a paddle wheel and wrapped the same time a rope with a length of 600 m from. After unwinding it anchored and pulled the second Zugschiff with the attached barges to be up, the rear Zugschiff supported the process by its own drive. Thereafter, the two tugs exchanged, the position and the same procedure is proceeded again. By anchoring easy, however much time was lost.

Since these experiments in the first half of the 19th century, the technique of chain shipping constantly improved and came on the Seine in France for the first time successfully applied. Other French rivers and canals were then provided with the chain. In Germany the chain in Elbe, Neckar, Main, Spree, Havel, Warta and Danube had been transferred and also in Russia, the chain shipping was widespread. A total of about 3300 km chain were installed in Europe.

Changes through the chain shipping in the second half of the 19th century

The chain shipping revolutionized the inland waterways, especially on rivers with strong currents. Compared to the formerly standard Treidelschifffahrt could significantly attract more and much larger barges a chain steamer. The possible payload of a single barge rose in a few years to fivefold. In addition, the transport of the chain was much faster and cheaper. The number of trips a vessel increased, for example, on the Elbe almost tripled. Instead of two trips the sailors were able to carry six to eight trips or instead of 2500 km to 8000 km to travel annually annually. The delivery times were shortened accordingly and reliable observed at the same time reducing costs.

Through the use of the steam engine it was at all possible to meet the increasing demand for transport capacities of increasing industrialization in the second half of the 19th and in the first half of the 20th century. The boatmen with their barges offered the chain shipping is also the possibility to compete against the growing competition from the railways. Before the introduction of chain shipping while were on some sections of the river steamer already worked as tugs and cargo ships, but they did not lead to a breakthrough in mass transport. The steamer was due to its dependence on the water level of the river and market economic interests do not guarantee as regular transport. Only regular schedules with fast connections, as well as guaranteed, low Befördungsentgelte the chain shipping could towage be competitive.

With the development and dissemination of new drives like screw drive and diesel engine in the first half of the 20th century, self-propelled vessels are continually stopped by. The development of river systems and competition from road and rail reduced the profitability of designed for continuous towing chain shipping industry. Crawler tractors came only sporadically on particularly difficult sections of the river are used.

Distribution in Europe


In 1839, the first technically and economically successful chain steamer " Hercules " was built and used on a 5 to 6 km long, flow- rich section of the Seine within the city of Paris. At precisely this section of the river de Rigny incidentally, was a few years earlier failed due to technical difficulties.

Starting from Paris, the chain shipping spread from 1854 to the river upstream Montereau city at the mouth of the Yonne, and downstream to Conflans (at the confluence of the Oise ). From 1860, the expansion occurred in the direction of His mouth even to trait. The maximum total length of the chain in the Seine was 407 kilometers. Added to this was in 1873 still a 93 -kilometer route on the Yonne itself ( between Montereau and Auxerre).

The nature of the river bed of the Seine offered optimal conditions for the chain shipping. The river was equally deep, had a relatively steep slope and the bed turned out to be sandy and regularly. In contrast, the rivers, the source of which lies in the Alpine region, were less suitable. This resulted mainly in severe floods large quantities of sand with them. The chain was buried in tests of the chain Cruise on the Rhone repeatedly on large stretches of sand and rubble. The experiments on the Saône failed and were set relatively quickly.

Except on rivers served the chain shipping in France also ship to transport channels. The tunnel in the area of the summit level were very long and electrically driven chain tugs dragged the ships here. Due to the lack of ventilation of the tunnel system, the electrically operated chain tugs are also after the introduction of self-propelled motor vessels partly still in operation today.


In Belgium wrong from 1866 chain steamer on the Canal de Willebroek between Brussels and the confluence with the Rupel. In contrast to the chain tugs in France and Germany came a system of Bouquié used, in which the chain was not performed on the center line of the ship, but only over a sprocket on the side of the ship at the chain tugs in Belgium. The chain wheel had been occupied with teeth to prevent the sliding of the chain. Every day perverse about five hauls in both directions, each train contained 6 to 12 ships.

German Empire and Empire of Austria

Elbe and Saale

In Germany the shipping chain began in 1866 with the laying of an iron chain along the Elbe. The first regular towing with a chain steamer was realized on a section of the Elbe between Magdeburg -Neustadt and Buckau. The length of this route was about three quarters of a Prussian mile ( well 7.5 km - length of the route thus 5-6 km). There, the Elbe by the Domfelsen a particularly high flow velocity. The Hamburg- Magdeburg steamship company operating there, the chain steamer.

The first two steamers on the Elbe were 6.7 meters wide and 51.3 meters in length with about 45 kW motorized (60 hp) and subjected to four barges up to 250 tons. 1871, the chain was already from Magdeburg to Schandau on the Bohemian border. Three years later expanded the Hamburg- Magdeburg Dampfschifffahrtsgesellschaft the route northwest to Hamburg. With a total length of 668 kilometers rattled up to 28 crawler tractors the same upstream. In the years 1926/27, the chain shipping has been in wide sections of the same set and lifted the chains. The chain steamers were used only in the most difficult sections. The final section in Bohemia was discontinued in 1948.

At the Saale, the line was put into operation in 1873 from the mouth of the river Saale to calbe and extended to the year 1903 and according to Hall (105 km chain). The last chain ship on the Saale reversed in 1921.


After the granting of a license to carry the chain shipping in 1869, the chain of the Danube Steam Navigation Company between Vienna and Bratislava was moved (German name for Bratislava). However, in 1871 it came up with some sections already banning the chain shipping. As of 1881 drove chain ships on the Danube also pointed to Linz. There were ten chain vessels in use. Increasingly Breaking Chains ( on average once per trip) were 1890, the reason for the conversion of the chain ships in tugs. In 1891 the chain Schifffahrtsbetrieb between Regensburg and Hofkirchen was built (113 km). In 1896 it came to the setting of the chain travel by boat between Vienna and Ybbs, 1906 and then to adjust the shipping chain between Regensburg and Hofkirchen.

Due to the strong current on the Danube, the Chain ships could not go on the chain down to the valley. They had, therefore, as an additional drive large side paddle wheels with 300-400 hp.


The 15 -kilometer lower Brahe (Polish Brda ) served as a link between the Vistula and the well-developed network of waterways with Western Europe. This waterway was particularly important for the transport of timber, but had the raft timber be towed upstream to the Brda River between the mouth of the Vistula River and the city of Bydgoszcz lock. To this end, horses were used on only about 26 meters wide, tortuous and relatively fast-flowing section of the river for a long time. On 12 November 1868, the owner of the responsible for the haulage Bromberger driver Comptoirs taught for a license to launch a chain drag operation on the lower Brahe to the government in Bromberg.

The concession of 3 June 1869 was limited in accordance with the application for 25 years and essentially corresponded to those applicable to the same Prussian regulations. Immediately afterwards in the summer of 1869 began the first test drives with a built by Maschinenfabrik Buckau chain steamer. The operation, however, had to be adjusted again in the autumn, as the tug could not provide the required performance and speed. A replacement tractor of sufficient power could be used from the summer of 1870. Nevertheless, only one or two trips could be carried out per day. Only with the construction of a stitch through most critical stretch in March 1871, and the procurement of a second chain steamer in the spring of 1872, a significant proportion of rafts are transported through the chain tugs.

The steamboat made ​​in the field of Brahemündung along the rafts and dragged them about a kilometer upstream. Here he handed over the 100 -meter long and 7.5 meter wide rafts to the second steamer which handled the remaining 14 miles to the city of Bydgoszcz lock. The transport was profitable and the number of chain steamer was increased to four. On April 30, 1894, the Minister of Trade and Industry and the Minister of public works extended the concession by another 25 years.


By 1878 also went on the Neckar between Mannheim and Heilbronn, the first track-laying tractors with nine punts in the appendix to ride. The operation of the chain shipping defeated the chain boat trip on the Neckar AG. As the 1930s began regulating the flow through barrages and thus the expansion of the great waterway, this meant the end of to date still profitable Neckar- chain towage and their replacement by large barges.

Havel and Spree

Also on the Havel, there was briefly experiments with the chain shipping. Although the flow of the Havel has always been low, could be towed with a chain cost steamer at the same time a large number of loaded barges. On the Havel and the Spree between Pichelsdorf near the former town of Spandau and Kronprinzenbrücke, the sub- tree at the edge of the then Berlin, which was founded in 1879 by two Englishmen Berlin Crane Company commenced on 16 June 1882, a chain shipping. In Havel country there have been numerous brickworks whose products were transported almost exclusively by boat. In the summer of 1894, the chain navigation on the rivers Havel and Spree was adjusted. The development of the tugboat propeller aircraft had replaced the chain shipping.


Also on the main there was the chain of navigation in the period from 1886 until 1936. The chain was in the approximately 396 km long navigable river between Mainz and Bamberg. Up to 8 chain tug boats were on the river Main in use. The chain was taken and recovered after 1938 from the Main. The chain ships on the Main were also called Maakuh or Määkuh.


The "Volga - Twer'sche chain shipping company " taught since 1871 a drag operation on the upper Volga between Rybinsk and Tver. The approximately 375 km long river section was poorly regulated and often had only a water depth of 0.52 m. The dividend was achieved only gering.Im 1885 were 10 chain steamer with a power of 40 PS and 60 on the Volga in use.

On the Scheksna the chain shipping was also established in 1871 and operated by the " chain Steamship Company on the Scheksna " based in St. Petersburg. The chain stretched to a length of 445 km from the mouth of the Volga to St. Petersburg. Initially, the chain towing achieved poor results. Subsequently, the company terminated the chain boat trip on a about 278 km route with very slight slope and replaced it with a tugboat operation. On the 167 km long distance remaining with a strong current, the chain shipping services provided in some years a dividend of about 30%. 1885 put the company on this river section 14 chain steamer with an output of 40 hp one.

Technical Description

Chain tug

The chain was lifted at the bow of the ship an extension ( jib ) out of the water and out on the deck along the ship's axis to the chain drive in the middle of the ship. The power transmission from the steam engine to the chain was mostly on a drum winch. From there, the chain carried on the deck at the stern and to the boom back into the river. Due to the lateral movement of the boom and the two both in the front and rear-mounted rudder, it was possible to store the chain even at flow bends back in the middle of the river.


The chain had to be financed by the chain shipping companies itself and was designed as a frameless steel chain. The individual chain links consisted of a good welding rods with low carbon content. Depending on the section of the river The rods had a typical thickness of 18 to 27 millimeters. Nevertheless, it always came back to continued fractions. Every few hundred meters, shackles were ( Kettenschlösser called ) that could be opened when met two crawler tractors. Most of these high-quality chains were made ​​in England or France.

Encounter between mountain and downhill driving chain vessels

Be met two chain ships, so a complicated evasive action was necessary, in which the chain was passed through an auxiliary chain to the other tractor. This maneuver meant for towing association for the ride up a delay of at least 20 minutes while the ship talfahrende a loss of time of about 45 minutes suffered by the maneuver. By introducing auxiliary drives the chain tug went on the decline outside the chain, and evasive maneuvers accounted for.

Experiments with an endless chain

To avoid the large costs of the acquisition of a chain or cable, carried out by Dupuy de Lome on the Rhône experiments with an endless chain. The tug brought it with his own chain. The chain was not taken into the prow (bow) into the water and lay down by the dead weight on the river bottom. At the stern ( rear ) the chain was pulled up from the water and transported by the chain drive on the deck of the ship forward. Under the assumption that the lower portion of the heavy, self-contained chain is prevented by the river bed from sliding, the ship is moving forward. This type of drive was not economically used as a reasonable power transfer is given only when an adapted chain length. If the water depth is too high, reduces the length of the chain section which comes to rest on the river bed and thus the required friction. Too little water depth, the chain has too great a length, and would not be drawn out, but in clusters to lie on the ground come. A variation in the depth of flow so difficult controllability of the vessel significantly.


In order to operate the chain shipping, require the person responsible for the chain towing company a concession. The concession guaranteed the companies the exclusive right for this type of ship transport. Since the purchase of the chain and the chain tug for the operator represented a high financial burden, offered the concession a certain security. However, the competition from the railways, with wheels or the Treidelzug remained unresolved. In return, the rights and duties towards the sailors were regulated in the concession but. Every boat had to be conveyed to the state established rates.

Comparison chain tug - Radschleppdampfer

The chain shipping had to face not only the competition with the railways, but also got the competition on the waterways clearly felt. Compared with Radschleppdampfern the chain steamer had all advantages where difficulties have arisen for shipping, such as rapids, sharp bends of the river and shoals.

Flow and flow velocity

With a wheel or screw steamer for the propulsion of the water is pushed backwards. A significant part of the energy is converted into Wasserverwirbelung and is not so for the propulsion of the vessel available. The chain steamer on the other hand pulls forward on the fixed chain and thus can convert a much larger share of its steam power into propulsion. With the same tractive power, this results in a lower by about two-thirds of coal consumption.

At a higher flow rate of the river, the advantage shifts more and more in favor of the chain steamer. Ewald Bellingrath introduced in 1892 following general rule: At an average slope of the river to 0.25 ‰ paddle steamers were superior. Between 0.25 and 0.3 ‰ gradient of the two peak types are equivalent. Above 0.3 ‰ had to use chain steamer advantageous. From a slope of 0.4 ‰ would get steamer increasing difficulty and need from 0.5 ‰ gradient completely without a tow transport.

The practical experiences showed that free -propelled wheeled tractors with 400 hp ( 300 kW) at a flow rate of 0.5 meters per second (1.8 km / h), a speed of about 3 meters per second (10,8 km / h) to achieve. This would allow them economically tow up to a flow of 2 meters per second (7.3 km / h). Even larger gradient falls could be overcome if these constituted only a short distance. Due to a decline in the Schlepptaue with wheels could overcome the obstacle. If the attachment of cargo ships came into this area, the steamer had already conquered the area with higher flow rates and was able to realize its full traction again. At a current velocity over 3 meters per second, the power output would drop to zero. Many of the fall gradient were relatively short and could be overcome by the maneuver described by Radschleppern.

However, too strong current at high water also could be problematic for the chain shipping. Depending on the design of the riverbed resulted in strong attachment to a Aufschotterung movements and thus to a covering of the chain with boulders and stones. A clip containing rich riverbed boulders or large sections of the Danube led by hooking the chain as a hindrance to the chain shipping.

The churning of the paddle steamers water also caused significantly stronger wave movements. The waves could lead to an increase shore damage. The additional currents and waves have caused an additional resistance for solid cargo ships. Behind a chain tug, the appendix was, however, in calm waters.

Water depth

Some chain tugs are designed with a shallow draft of only 40-50 centimeters for use at very low water levels and thus adapted to the circumstances of many rivers of the time. Even with a water depth of 57 centimeters a powerful operation on the Neckar was still possible. Paddle steamer on the other hand need for an economic application significantly greater water depths of 70 to 75 centimeters. In case of heavy flow, the minimum water depth for paddle steamers additionally increased. Screws tractor also need a large water depth to operate effectively. Only one screw, which is located deep in the water, can produce a sufficient propulsion.

Chain ships not only have a shallow draft, including their technical principle is advantageous for low water depths: In shallow water, the chain rises from the flat water and a very high proportion of steam power can be converted into propulsion. If the water depth is very high, so increasing the proportion of energy that is required for lifting the ascending chain. The weight of the pulling force is directed obliquely downwards and the efficiency decreases. Moreover, the maneuverability decreases with increasing depth.

Investment costs

The chain itself meant high investment costs for society. On the 200-kilometer long section of the Main river, between Aschaffenburg and Kitzingen is estimated for the first chain including laying over one million marks. This corresponded almost exactly to the total price of eight track-laying tractors that should be used on this section. The chain was subject to an ongoing maintenance and had to be replaced about every 5 to 10 years.

Costs even came to remodeling of ferries that hit once on this route with about 300,000 to Mark Beech The costs for the chain. This modification was necessary because the chain of the chain ships and the ropes of the ferries were not allowed to cross. Instead of the usual cable ferries therefore had to be converted to greed ferries.


The first chain ships were bound in their movement along the chain, that is, they put both the ascent and the descent on the chain back. At a meeting, there was evasive maneuvers with a high loss of time. On the 130 km long river Neckar with a total of seven chain used tractors that means a loss of time of at least five hours for the descent in six games. To bypass the maneuver, the barges were passed from one to another chain steamer on certain stretches of France. Such a transfer, however, was also associated with a considerable loss of time.

The towing operation with barges took place usually only on the ascent. Downhill the barges could be mostly to save money, drive. In case of heavy flow of operation with a long tow would have been dangerous. Should the chain tugs are forced to a sudden stop ( for example, by a continued fraction ), the risk was great that ships auffuhren rear to the front and so it was a disaster.

Radschleppdampfer were at least at the initial time of the chain boat trip on the mountain ride slower than the chain ships. On the descent, however, they were faster and were also able to take barges.

In addition to the technical limitations the chain tug carriers was determined by concessions rules that, for example, laid down the order of the carriage and the carriage charges. They could not respond flexibly to supply and demand as the company with Radschleppern therefore.

The end of the chain shipping

One reason for the end of the chain shipping was to increase the technical capacity of the new Radschleppdampfer. They had an increased tension at reduced coal consumption. The compound steam engine to the Radschleppdampfern consumed, based on the power output, only about half of coals. Such composite steam engines could not be used on chain steamers because of the jerky tightening. At the same time loaded high investment and maintenance costs, the chain shipping companies.

Another reason for the end of the restructuring were rivers. At the same many current regulations have been made, with more and more outweighed the slope and reduced the bends of the river and the shallows. Thus also the benefits of chain shipping is reduced.

At the Main and the Neckar numerous dams and locks were added as additional artificial barriers for the chain tugs. The damming of the river led to greater water depth and reduced at the same flow rate. Especially the long hauls had to be shared at the locks of barrages and funneled separately, which resulted in considerable loss of time.

Chain shipping in the literature

A humorous historical documentation comes from the American author Mark Twain, who describes in his travelogue from Germany, the chain boat trip on the Neckar as follows:

" We ran to the front to see the vehicle. It was a steamer - because in May had begun, be necessary to have a steamer Neckar up. It was a tug, and indeed a very strange construction and appearance. I had often watched him from the hotel and asked me how he 'll probably driven, because obviously he did not have a screw or blades. Now he came dahergeschäumt, made a lot of noise of various kinds and boosted him from time to time even the fact that he sounded a hoarse whistling left. He had attached the back nine barges, who followed him in long, narrow row. We met him in a narrow place between dams, and in the narrow passage was barely room for both of us. While he passed puffing and groaning, we discovered the secret of his drive. He did not go up the river with vane or screw, he pushed himself up by the fact that he put on a great chain forward. This chain is laid on the river bed and fixed only at the two ends. They seventy is miles long. It passes through the bow of the ship, a, revolves around a drum and aft unplugged again. The steamer pulls on that chain and drags himself by upstream or downstream. He has neither bow nor stern Strictly speaking, because he has at each end a rudder with a long blade and turns never. He used permanently both oars, and they are so strong that, despite the strong resistance of the chain to turn right or left and can walk around controlling curves. I would not have believed that you could run this impossible thing; but I've seen it done, so I know that it is an impossible thing that you can accomplish. "