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of the ship. Extra capacity is a more doubtful advantage since it cannot always be made use of, be- cause it is very seldom that either passenger or cargo ships have a full complement. Weight of machinery is not of paramount importance and is in any case, about equal for all types for similar duties. Fuel and main- tenance costs are recurring expendi- tures and play a most important part in the choice of the propelling equip- ment, and largely determine the dividend earning capacity of the ship ‘as a whole. The Fuel Problem N ORDER to appreciate the fuel problem and forecast the future with some degree of reliability, it is advisable to become retrospective and examine some of the factors that caused the rapid introduction of the oil engine. In 1890 the oil engine was slightly inferior in economy to the steam engine because it was of the low compression vaporising type. The following ten years witnessed the in- troduction and _ perfection of the high compression cold starting type so that by 1900 it had trebled its economy to become twice as efficient as the steam engine. No later than ten years ago, the oil engine as al- ready stated, consumed about one- quarter the weight of fuel required by coal burning steamships. A simple calculation showed that at the then ruling-prices of oil and favorite and would have made even more rapid progress but for the fear that the increased demand for oil would send its price up or cause a shortage. The price did go up until its advantage in fuel costs was al- most wiped out, but it still main- tained its popularity due to its other attributes, and to the fact that it was now firmly established as a reliable propelling plant. At the present moment the reci- procating steam engine has further improved its position by the adop- tion of special valve gears and an auxiliary turbine geared to the pro- peller shaft to utilize the exhaust steam, so that the determining fac- tor in the choice of propelling plant is now no longer one of fuel con- sumption so far as vessels of the above size, namely, up to 10,000 tons, are concerned. It is impossible to accurately analyse the reasons un- derlying any particular preference since they are so often merely a mat- ter of use and want, vested interests or associations. In some cases ship- owners have been so badly bitten by the choice of the wrong type of oil engine both for propelling and auxiliary purposes that they are glad to adhere to steam even at the ex- pense of efficiency. It may be taken for granted that coal producing countries will always build a large proportion of steam tonnage until such times as coal can be converted into oil on a commer- cial basis, but by that time the steam. Botor atte Aucustus of the Navigazone Generale Italiana. Gross Tons. coal the motorship could save the entire cost of its propelling machin- ery in the course of three or four years. This applied to the normal range of cargo vessels of about 8000 to 10,000 tons since the oil engine had not at that date, been developed in sizes to enable them to be ap- plied to fast passenger vessels such as might be used on cross Atlantic routes. The oil engine then became first 26 Bwilt 1927, of $82,650 Worlds Biggest Motor Liner engine may have improved in effi- ciency to such an extent as to main- tain its existence as an active com- petitor, a statement that is support- ed by the present trend of events that will now be referred to at some length. Economy of High Pressure. Steam Spain developments in high pres- sure and high temperature steam plants must cause the most enthusias- MARINE REvIEw—September, 1931 tic oil engine experts much concern, and it is well that the facts should be looked squarely and honestly in the face. At the moment the immediate danger to the eclipse of the internal combustion engine as the world’s most efficient propelling unit comes from steamships requiring something on the order of 40,000 shaft horsepower. For such powers it is possible to incorpo- rate all the refinements and fuel saving devices of the biggest land power plants, but there are no theoretical or mechanical reasons why the power can- not be progressively decreased until the requirements of the average tramp steamer are met and then the oil en- gine will be faced with severe com- petition in all but the smallest powers. The recent rapid progress made by the steam engine is well illustrated by the remarkable results achieved by John Johnson, superintendent engi- neer of the Canadian Pacific Steamship Co. The EMPRESS OF AUSTRALIA was re-engined in 1927, and gave an “all- in” fuel consumption of .71 pound per shaft horsepower. The DUCHESS class gave .625 pound, the EMPRESS OF JAP- AN .603 pound, and the latest one just out this year, the EMPRESS OF BRITAIN, achieved the wonderful figure of .57 pound. This represents a reduction of 20 per cent in the short space of ap- proximately four years. This has been attained with a pres- sure of 400-500 pounds which, judged by our modern conception of the prob- © lem, is very moderate, and is less than the pressure developed by the high effi- ciency oil engine. At 900 pounds pres- sure a fuel consumption of .5 pound can be guaranteed and as the limit is only reached at the critical pressure of 3000 pounds, it must be obvious to any World Motor Vessels N October, 1930, there were, according to the Bureau Veritas, 3840 motor vessels and vessels fitted with auxiliary motors of 7,486,000 gross tons, including 800 British vessels of 2,291,000 gross tons and 495 American vessels of 672,000 gross tons. Germany owned 431 vessels of 584,000 gross tons, and the three Scandinavian countries 763 vessels of 1,914,000. gross tons, of which 331 vessels of 1,056, 000 gross tons were Norwegian. As compared with October, 1929, this is an increase of 1,238,000 gross tons. The percentages by number and tonnage are given below:- Per cent y Mi number tonnage Britteien cco toe co. 20.8 30.6 American on) eas oe 12.9 9.0 Germano. oo ates 22 7.8 Scandinavian ..2.<..23.5 19.9 5:6 Other-flags:.< 025 o.oo. S552 27.0 World Merchant Vessels Under Construction December 31, 1930 (Vessels of 100 tons gross and up) Gross Per- No. tons centage Motors. soe eee 252 1,532;:7090-5 7. 29 OBAER Geo vas ene 232 98 84,034 42.30 Sail and barges. ... 18 97343 0.40 502 2,326,086 100.00 Oil tankers of 1,000 — gross tons and up i as in the 115 907,298 39.01 (rida Shipbuilding Returns) SSS SSS SSSESSSnSSsennnenngeeifeeeneeeee= Eo El FSSA ATEN CT eee ee ee eee