Doxford Economy
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The Doxford Economy Ship , also Doxford Economy Tramp, was a type of motor tramp ship built by the British shipyard William Doxford & Sons from Sunderland. The successful ship design , also known as Doxford Economy Tramp Design or Doxford Standard Design, was the world's first series-built motor tramp ship and was built in around 100 units in two series from 1934.
history
After the Doxford shipyard had already delivered its first motor ship with the Yngaren in 1921 , after the years of the global economic crisis it developed a motor tramp ship that should be able to operate profitably even in crisis years. The Doxford "Economy" trampoline was designed under the direction of J. R. Gebbie and Charles Doxford and K. O. Keller, who designed the engine. The "economy" referred not only to the operation, but also to the construction, which on the one hand had to be accomplished with as few tools as possible and on the other hand as far as possible with existing tools. The hulls were mostly welded and were powered by the newly developed Doxford “Economy” three-cylinder diesel engine.
A conventional tramp steamer of that time consumed between 30 and 40 tons of coal a day and reached a speed of almost ten knots, while the first economy ships reached a speed of ten knots and only consumed around 6.5 tons of fuel a day. The first shipowner to order a Doxford economy ship was Arthur Sutherland of the Sutherland Steamship Company from Newcastle. The type ship of the series was called Sutherland . The first series had a load capacity of around 8000 tons and an engine output of 1760 bhp . During the two and a half years in which 23 ships of the first series were built, the shipyard increased the load capacity to 9,000 tons and the engine output to 1,800 bhp. These ships ran almost eleven knots, for which around nine tons of fuel were needed daily.
An improved "Improved Economy Ship" type, of which as many as 76 ships were built between 1939 and 1945, even had a deadweight of 9500 tons and had an engine output of 2500 bhp. This allowed a speed of twelve knots with a daily fuel consumption of 9.5 tons. In contrast to the stems, the improved types had a forecastle, which helped them to behave better at sea. The first ship built was the Kassos . Like a significant number of the ships of the second variant, she was ordered by a Greek shipping company. The ship type was also used by well-known liner shipping companies of the time. Due to the great success of the type, the British Admiralty allowed Doxford's to continue to build it as the standard cargo ship type of the emergency construction program during World War II . Overall, the type during the war of 20 private shipping companies, including such well known names as was British India Steam Navigation Company , the P & 0 , the Anchor Line , Hain Steamship Company , the Bank Line , or Reardon-Smith and the Ministry of War Transport operated .
An advantage that became clear in the convoy trips of the war years was the possibility of bunkering the Doxford “economy” outside of Great Britain for entire tours, whereas steamships had to bunker coal on all calls home due to their higher coal consumption. But also a disadvantage became clear, the low ballast capacity of the type. This led to low travel speeds for convoys heading west. A number of ships were given side tanks to carry 500 tons of additional ballast.
There is no doubt that the positive experiences during the war years with traditionally discontinued tramp shipping companies played a major role in the switch to motor ships. After the trampers disappeared noticeably in the post-war period, the Doxford economies continued to operate for a long time, but were sold to Asia by the 1960s at the latest. Against the background of changes in sea trade due to new technologies such as RoRo or containers, but above all the bulk carrier , this conventional type of trampoline soon also disappeared. The last units were scrapped in the early 1970s.
literature
- Alan McClelland: Milestones in tramp ship development . In: Roy Fenton (Ed.): Ships in Focus Record . No. 1 . Ships in Focus Publications, 1996, ISSN 1363-1675 , pp. 45-53 .
Web links
- Sarah Stoner: Radical ship design revived Wear yards . In: Sunderland Echo (English)
