Turbine-powered Paddle Boats

Gallery opened 29 Feb 2020

Updated 8 Mar 2020
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Paddle boats were used as harbour tugs long after their use had been abandoned on larger vessels, because of their great manoeuvrability. By turning the side-paddles in opposite directions a tug could turn round on the spot. Paddle tugs almost always had reciprocating engines, usually one per paddle, as they were easily reversed. Turbines, on the other hand, are not reversible; but the Dordrecht was a river tug rather than harbour tug, and was built to tow trains of barges; very great manoevreability was not required. Presumably the idea was that turbines would be more efficient than reciprocating engine for a river tug. The idea does not seem to have caught on, as the four ships listed below are the only turbine paddle-steamers currently known. Perhaps the introduction of the Diesel engine had something to do with this.

Three experimental paddle tugs powered by turbines were built for use on the River Rhine in the mid 1920s, and one on the River Rhone. At present the Dordrecht is the only one of the four on which information has been found.

Turbine supplier
PT Zurich (1922)
Escher Wyss (Zurich)
PT Dordrecht (1925)
Schiffs-und Maschinenbau Gesellschaft (Mannheim)
Brown Boveri Company
PT Toulon (1929)
PT Rhone (1931)
Escher, Wyss (Zurich)

Left: The Dordrecht turbine paddle tug: 1925

The Dordrecht was built for Dutch owners by Schiffs-und Maschinenbau Gesellschaft of Mannheim, with turbines supplied by the Brown Boveri Company. She was fitted with collapsable funnels to enable her to get under bridges and so go beyond Basel in Switzerland. She was one of the longest Rhine tugs in existence at 77.81 metres and was 22.20 metres wide.

She was reboilered in 1954 but withdrawn from service in 1957; some boiler parts were reused in another vessel, while the forward part of her hull used as a boathouse at Mannheim.

Image from The Brown-Boveri Review for May 1925

Left: The turbine installation of the Dordrecht: 1925

One high-pressure, and one low-pressure forward turbines were fitted. The low-pressure turbine is nearest the camera; note the large exhaust duct that would be connected to the water-tube condenser. The large casing in the centre contains the secondary-reduction main gearwheel.

Two stages of gearing reduced the forward turbine speed of 3600 rpm to 330 rpm, and then a paddle speed of 38 rpm. There was one reverse turbine. The indicated horsepower was 1500 HP at a turbine speed of 3600 rpm. There were two Scotch boilers with a heating surface of 250 sq m each; steam conditions were 14 kg/sq cm (200 psi) at 300 degC.

The equipment to the right of this is test equipment; the paddle shaft turned too slowly for a conventional dynamometer to measure the output power, so it was geared up to about 255 rpm in the box just to the right of the main gear case, and then drove the dynamometer at the extreme right. Trials were conducted in June 1923.

Image from The Brown-Boveri Review for May 1925

Left: The turbine installation of the Dordrecht: 1925

The high and low pressure turbine shafts each had their own primary reduction gear, using double-helical gearing. The two output shafts then drove a single central gear for the secondary reduction gearing.

The reverse turbine appears to be the small item at the extreme left of the two left-hand drawings; it drives one of the intermediate shafts directly. It does not look as if it produced much power, but presumably the vessel would only be making occasional movements astern. The round thing to the left of the top-right drawing is the water-tube condenser.

Image from The Brown-Boveri Review for May 1925

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