Chain boat navigation on the Neckar was a special type of tugboat navigation in which chain steamers with several towed barges pulled along a chain laid in the river. It was used from 1878 between Mannheim and Heilbronn and from 1884 as far as Lauffen. Chain shipping considerably reduced the transport costs for skippers compared to the hitherto customary towage by horse, and made ship transport competitive with the railway once again. The progressive canalisation of the Neckar and the barrages required for this made chain towing more difficult and uneconomical. It was increasingly replaced by tugs with propellers, and was discontinued in 1935 with the complete expansion of the Neckar.
Situation prior to chain shipping
River The flow conditions of the Neckar varied considerably along its course. On the approximately 113 km long stretch of river from the harbour in Heilbronn to its mouth in the Rhine, sections of the river with a steep gradient of 1:350 alternated with shallow sections with a gradient of only 1:10,000. If sections with a gradient of more than 1:700 are described as rapids, then this applied to around 7 % of the stretch, i.e. around 7840 m. In addition to the difficulties caused by the variation in gradient, there were also strong bends in the course of the river.
The river bed consisted mostly of shell limestone and coloured sandstone; however, there were rock sills in some places along the course of the river. The water levels of the Neckar varied greatly depending on the season and the amount of precipitation. The highest water levels were between 6.6 and 14.6 metres, depending on the section of the river, while the Neckar fell to less than 0.56 metres at low water in summer. In the very dry year of 1865, water levels below 0.56 metres were measured on 210 days, whereas this low level was only reached on one day in 1869. The low water levels significantly hindered ship traffic. In winter, frost also hindered navigation for an average of three weeks.
The flow rate of the water was between one and three metres per second, depending on the gradient and water level in the rapids area. The river conditions were therefore not particularly favourable for the circumstances at the time, but not overly obstructive either.
Transport by ship Until the 18th century, boat transport on the Neckar was traditionally carried out by people pulling their boats uphill from the land on towpaths. The boatmen let their boats drift downstream with the current. With the expansion of transport capacities, ships became larger and larger and shipping was reliant on horse-drawn towage. A typical ship's train consisted of a main ship with a mast, an anchor and an oar yacht. The cargo distributed between the three boats was typically around 120-150 tonnes. The crew consisted of the ship's owner, two sailors and a deckhand. In addition, there were six to ten draught horses harnessed one behind the other, which were ridden by four to five linesmen.
It was possible to cover about 20 kilometres a day in 5 hours, so it took about 5.5 days to cover the distance from Mannheim to Heilbronn. The horses had to be transferred from one bank to the other at five points, and additional horses were needed at certain points. The riders' wages were negotiated individually with the shipowner and varied according to water levels and demand. Operating costs were therefore almost impossible to plan. It was not until 1863 that annual contracts were signed. However, this did not prevent costs from rising steadily. In most cases, the income from the freight barely covered the transport costs. In some cases, the uphill journey was loss-making, and the downhill journey was only marginally profitable.
The main goods transported upstream were coal and colonial goods, while downstream were mainly table and rock salt from the and Wimpfen saltworks, timber and lumber, stone from the Odenwald quarries and grain. The total volume of goods transported on the Neckar at Heilbronn increased significantly from 25,600 tonnes (1836) to 79,600 tonnes (1854) and around 115,000 tonnes (1872). At the same time, competition from the railways became increasingly fierce. Railway lines were built mainly on the Mannheim-Heidelberg (1840), Heidelberg-Neckargemünd-Meckesheim-Neckarelz-Mosbach (1862), Meckesheim-Rappenau (1868) and Rappenau-Jagstfeld (1869) routes. The railway offered low fares and high speeds. For the boatmen, this meant that their declining incomes were offset by ever-increasing costs, leading to fears that shipping would cease altogether within a few years.
The first attempts to switch to steam were made as early as 1841 with a paddle steamer. However, these failed due to the difficult conditions on the Neckar. The low water level, the narrow bends and the strong current in the area of the numerous rapids made operation impossible or at least unprofitable, depending on the water level.
Chain boat navigation
Planning and concession Faced with increasing competition from the railways, the merchants of Heilbronn saw their town's importance as a major freight hub at the end of the navigable Neckar River in jeopardy and sought an economical means of water transport. Without shipping as the only competitor to the railways, price increases would have been inevitable. In addition, the danger of a monopoly on rail transport had become apparent during the Franco-Prussian War (1870-1872). The military use of the railways disrupted civilian land transport, which could only be maintained by shipping.
As a result, the Heilbronn Board of Trade set up a provisional committee in 1872 to introduce chain boat shipping on the Neckar. To analyse the situation on the Neckar, the committee enlisted the help of , director of , the road and hydraulic engineering inspector Baurat von Martens from Stuttgart and Max Honsell, a member of the Baden Directorate of Hydraulic and Road Engineering. All three concluded that chain navigation alone, as had been practised on the Elbe since 1866, would be advantageous on the Neckar from a technical and financial point of view. In this technique, chain steamers pull themselves along a steel chain sunk in the river together with an attached tow. , on the other hand, is unsuitable due to the shallow water depth and tight bends.
On 2 October 1872, the committee applied to the Württemberg government for a concession for chain shipping, which then entered into official negotiations with the governments of the other two riparian states, Baden and Hessen. However, when the concession was in sight at the end of 1873, problems arose in raising the necessary share capital. Due to the general economic development of the previous two years, a lot of free capital was tied up in companies and there was little willingness to invest in new projects. For this reason, the committee asked the Württemberg royal family for a subsidy or at least a state guarantee. In a letter of May 1874, the mayor of Heilbronn, , argued that the future of Heilbronn depended on the preservation of shipping and that the state of Württemberg, as the owner of the salt works and the forest, should also have a clear interest in competitive shipping on the Neckar.
The Guarantee Act of 1 July 1876 provided for the state of Württemberg to issue a state guarantee to a public limited company for the construction of a chain and cable shipping company on the River Neckar. The state guaranteed an annual subsidy of up to 5 per cent of the paid-up share capital for 20 years if the company's annual earnings were insufficient to cover operating costs, and a 5 per cent dividend for shareholders. At the same time, the company undertook to repay previous grants if net profits exceeded 6%. If past subsidies were not to be repaid, the state was to share 50% of the surplus.
In the summer of 1877, a subscription of five per cent shares was established. The city of Heilbronn acquired 500 of the 6,000 shares offered, each with a nominal value of 300 Reichsmarks. After the share capital had been secured, the board of directors of the joint-stock company was elected at the constituent meeting of Schleppschifffahrt auf dem Neckar AG, headed by the businessman and , who had in the meantime been appointed Lord Mayor. In the same year, the company received the 34-year concession from Hesse (27 August), Baden (22 September) and Württemberg (1 November). The content of the identical concessions was in particular the endeavour to prevent one-sided preferential treatment of individual ships. All vessels suitable for towing operations were to be transported in the order in which they were registered. The tariff for the transport was to be determined in consultation with the Ministry. This was divided into a fee for towing the empty barge and a weight-based part for the cargo.
Operation On 23 May 1878, a richly-flagged towboat, the Kettenschiff No. I, was waiting at Wimpfen with a train of empty Neckar barges for the probably more than 500 invited guests. Among the guests were and other high-ranking officials and members of parliament from neighbouring states. The next day the steamboat travelled to Mannheim. From there she set off on her first real tow with nine barges attached (total load 360 tonnes) and reached Heilbronn on 27 May. The journey took about half the time of the horse-drawn train. At the same time, the costs were significantly reduced. Shipping became competitive again. On 15 June 1878, King Charles I inspected the equipment and travelled with it from Neckarsulm to Heilbronn. A new chain steamer was put into service in the following months by September. In 1880, the fifth chain steamer was added.
Skippers were quick to embrace the new chain towing service. Between 1878 and 1883, the number of vessels towed and cargo transported increased steadily. By the mid-1880s, upriver traffic on the Neckar had roughly doubled compared to the mid-1870s, despite the opening of the new Neckargemünd-Eberbach-Neckarelz-Jagstfeld (1879) and Jagstfeld-Heilbronn (1882) railway lines, which ran parallel to the river. As the company's income increased, the returns paid to shareholders were between 5.5% and 6.6%. In 1884 there was a slight downturn in shipping. Due to a prolonged, extreme drought, water levels were very low throughout the year, reaching a low of only 45 cm on two occasions. Not only the low rainfall, but also the diversion of water by farmers and the damming up of waterworks at night meant that the tugs had to interrupt their voyages repeatedly due to lack of water. As far as possible, coal and hawsers from the chain steamers were transferred to tenders to reduce the draught. This meant that shipping operations could be maintained down to a minimum water depth of 50 cm.
At all times, the tug company ensured that its prices were competitive with those of the railway, while maintaining its own profitability, so that boatmen could offer their services at competitive prices and still make a reasonable living. For example, it gave discounts to boatmen when water levels were low. The state of Württemberg itself had a vested interest in promoting trade on the Neckar. The income from the trade in Heilbronn, as well as the income from the towing service, went directly to the state of Württemberg. As a result, shipping was favoured at the same cost and the Württemberg State Railway was instructed to transport its coal to Heilbronn by ship. Three steam cranes were specially built by the Heilbronn tugboat company to unload the ships.