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Trans RINA, Vol 152, Part A2, Intl J Maritime Eng, Apr-Jun 2010


1900s, successful designs of burner had been developed. From about 1914 all the major vessels of the Royal Navy used oil fuel, not just the newly developed submarine with its internal combustion engines. Although more expensive than coal either on a weight or calorific value basis, the weight of fuel was less, it could be stowed in awkward compartments like double bottoms, it greatly reduced the number of stokers to be carried, and it did away with the slow and dirty business of coaling ship. Higher powers also required improvements such as the compact reliable Michell thrust block.


The same decade (1900) saw the application of the oil engine to marine propulsion, initially only in small vessels. Its greatly increased thermal efficiency (32%) – hence lesser fuel load – quick starting and compact space and uptakes spawned many designs. After Burmeister & Wain had developed the directly reversible diesel, the way was clear to use them in deep sea ships, resulting in the Danish Selandia of 1912. Take-up of the diesel was delayed by the First World War, where maximising production from existing manufacturing facilities was paramount. Between the wars, different shipowners took different


views on the potential reliability, more expensive distillate fuel,


problems of lower greater


maintenance and repair bills, more skilled operators and modest power per cylinder. Thus steam reciprocators retained a significant share of the marine propulsion market into the 1940s, indeed the 2648 Second World War Liberty ships all used a British design of triple expansion engine.


There was little evolution of ship types between the two world wars, not so much due to lack of technology but due to economic stagnation and little growth in world trade. Apart from transatlantic liners reaching 80,000grt and 30knots (Queen Mary, Normandie), cargo ships and tankers remained around the 8000grt mark, whose speeds had barely increased either, with around 11 knots. Progress was more in refinement of designs, with tank testing producing better hull forms (including the Maierform), streamlined aft ends and rudders, exhaust turbines added to steam reciprocators, e.g. Bauer-Wach. The first steel hatch covers appeared, offering greater strength, safety and quicker opening and closing – a boon to coastal colliers with their short voyages and low freeboards. But the traditional steel beams, wooden boards and tarpaulins were not completely replaced by designs like MacGregor covers until the 1950s. Wireless became mandatory on ships over 1600grt in 1919 which not only reduced casualties but improved commercial efficiency. Electrical generating capacity increased, so electric motors started to replace steam driven auxiliaries, especially on diesel ships.


Higher standards of subdivision in passenger ships were introduced in 1930. Particularly in passenger carrying ships (there was as yet little challenge from air transport) innovations


were introduced such as partial air


conditioning (first class passengers only!), fin stabilisers, gyro compasses and echo sounders. Nozzle propellers were installed in tugs to increase thrust, while the first controllable pitch propellers appeared in a few smaller ships. Crew accommodation slowly improved. Seamen moved from forecastle to poop (more space, lesser motions, drier), separate eating and washing places (with hot water!) were introduced, and refrigerators allowed a wider range of food to be stored – no more coops for live chickens or sheep! As yet number of crew remained high at 40-60 on a typical deep sea cargo ship, only showing a reduction in ships where oil replaced coal.


Figure 8. Burmeister & Wain in Copenhagen produced the first diesel engine for deep sea ships for cargo vessel Selandia in 1912, offering much lower fuel consumption than steamships, albeit at higher construction cost. Over the next decade, many designs appeared but few were successful. The Doxford opposed piston engine with good balancing characteristics went


to sea in 1921 and


remained a popular engine for the next 40 years. Here one of their 6 cylinder 6600bhp engines for the twin screw Portuguese liner Angola is in Hawthorn Leslie’s erecting shop in 1948.


Figure 9. Welding technology, although developed in the 1900s, became more widely used in the 1930s, especially for tankers. Making really oil tight riveting was difficult, so it was no surprise that they were the first ship type to make wide use of welding. In Second World War, welding was used for American mass production of Liberty cargo ships. Full scale structural tests were made on welded and riveted ships in Britain; the cross section


©2010: The Royal Institution of Naval Architects


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