SF Ammonia

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SF Ammonia, Mæl, Norway, Rjukanbanen
Name: DF Ammonia
Operator: Norsk Transport
Port of registry: Skien, Norway
Route: Tinnsjø railway ferry
Builder: A/S Moss Værft og Dokk
Cost: NOK 829.485
Launched: 18 June 1929
Out of service: 1991
General characteristics
Tonnage: 929 gross tonnes
Length: 70.4 m (231 ft)
Beam: 9.5 m
Draught: 3.9 m
Installed power: 2x 336 kW steam engines
Speed: 12 knots
Capacity: 250 passengers

SF Ammonia is a steam powered railway ferry on Tinnsjø that connected Rjukanbanen with Tinnosbanen, Norway. The ferry was one of the four railway ferries on Tinnsjø that was used by Norsk Hydro to transport chemicals from Rjukan to the port in Skien. The ferry is the only remaining steam powered railway ferry in the world, and can still be seen docked at Mæl.[1]


Ammonia is capable of 17 railway cars, totaling 630 tonnes on 120 meters of track—double wide standard gauge, in addition to 150 passengers. She has two steam engines each at 300 kW (400 hp), and can do 12 knots (22 km/h).


Ammonia was the third railway ferry built for Norsk Transport; when she was ordered in 1928 the two older ferries Rjukanfos and Hydro were too small. She was in reality an alternative to extending Hydro by at least twenty meters. Diesel traction was considered, but at the time diesel was not optimal for ships. She was built by A/S Moss Værtft & Dokk at the docks on Tinnsjø and launched on 18 June 1929 and cost NOK 932,000 to build, of which Norsk Transport paid NOK 829,485.[2]

She quickly became the main ferry; in 1939 she was in service 340 days, while Hydro operated 32 days and Rjukanfos 18. After the sinking of Hydro in 1944, Ammonia had to do the main hauling across the lake, and by September 1944 she was performing eight round trips each day. In 1951 the coal boilers were replaced with petroleum-fueled ones.[3]

When the diesel-powered MF Storegut was launched in 1956 Ammonia was down-graded to a reserve ship, mainly serving when Storegut was for repairs. In the 1970s Norsk Transport considered rebuilding her to diesel-power[3] She was taken out of service when the railways ceased operating in 1991, but remains docked at Mæl in operational condition.


  1. Helge Nisi. "Tinnoset" (in Norwegian). http://home.online.no/~hnisi/tinnoset.htm. Retrieved 2006-12-13. 
  2. Payton and Lepperød, 1995: 86–88
  3. 3.0 3.1 Payton and Lepperød, 1995: 90–92


  • Payton, Gary and Lepperød, Trond (1995). Rjukanbanen på sporet av et industrieventyr. Rjukan: Maana Forlag. 

External links

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