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Mir ocates Use of Motorships Engineers Advance Merits of Such Craft and Urge CEAN freight rates reduced in O recent months to prewar levels should bring forcibly to the at- tention of American shipowners the great economic importance of the in- ternal-combustion engine for ship pro- pulsion, although it is not claimed that the diesel engine is a complete remedy 'for the present predicament of the American merchant marine. The sit- uation in which American shipping now finds itself is analogous to the early transition from sail to steam. This country then failed to keep pace with Great Britain, which gained a lead that was only partly overcome, due to the condition brought about by the late war. In the recent shipbuilding emergency, efficiency of type was subordinated to the expediency ot rapid construction and quantity production. Many warn- ings were sounded to those in author- 'ity at the time in regard to the dan- 'ger of entirely ignoring the larger motorship in the emergency construc- tion. However, this defect in build- ing could have been greatly remedied by recasting the uncompleted program immediately after the armistice, as car- ried out by other countries, to meet the inevitable competitive conditions of peace. Contrasted with our past policy in reference to motorships is that of Great Britain and Scandinavian coun- tries, in particular, which fostered the: motorship during the war, and, since the armistice two and a half years ago, have rapidly built motorships al- most to the exclusion of the less effi- cient steam cargo vessels. As matters now stand we find ourselves in the possession of a large government owned fleet, almost wholly steam driv- en, which private owners are reluc- tant to purchase or operate. The question accordingly is presented to us, as naval architects and marine en- gineers, as to the best method by which the inadequacy of the situation can be met, whether to advocate the conversion of the most efficient of the existing steam vessels to diesel drive or build new motorships, and the best ese eagle gelamed eee Ne York, May 26. Mr. Metten is chief engineer of the William Cr Building Co., rep ee Sons' Ship & Engine BY JOHN F. METTEN AND J. C. SHAW systems which are to be recommended. It hardly is necessary to state in de- tail the particular advantages of the motorship over the steamer which are fairly well conceded and undoubtedly well known. More in regard to de- tail of the application of the internal combustion engine, pointing out the various advantages and the defects of the different systems, will be attempt- ed to be presented. A critical analysis of two vessels of a given size, pro- pelled by steam turbines and diesel engines, to show the economic im- portance of the latter, is given in the accompanying table. It is to be hoped the authors will be pardoned if undue reference is made to Burmeister & Wain, Copenhagen, with whose work they are mostly familiar. As common- ly recognized, this pioneer company has been mostly responsible for the present accepted high standing of the motorship. There have been com- pleted 67 vessels to their own system representing 580,000 tons deadweight and 214,000 diesel indicated horse- power, totaling more tonnage than all the other makers combined for this class of vessel. Others Have Developed Motors Of other continental builders , who have done much also to promote de- velopment of the motorship with their respective designs may be mentioned Werkspoor, Sulzer, Ansaldo San Gor- gio, Krupp, Polar Diesel and Vickers of England. Burmeister & Wain, like Werkspoor, have always held to the 4-cycle engine as best suited to this class of service, where utmosi reliability combined with economy is of first consideration. Their epoch making first vessel, the SELANDIA, was put into service in February, 1912, being 7400 tons deadweight, having twin screws, and designed for 10% knots. The two main engines, which have eight cylinders each, develop 2500 total indicated horsepower when running at 140 revolutions per minute. This vessel, now entering her tenth year, with a total mileage of nearly 500,000, has proved the same unqualified success as her successors and is today in steady » service in the Far Eastern trade, while hundreds of steamships completed eight years later are laid up on account of 300 Study of Means to Develop American Motor Fleet their areatiy inferior operating economy, Eight «cylinders were used to limit the diameter to 530 millimeters, or 2} inches, which was the same as the firm's largest land engine at that time. Later the number was changed to Six, which is cheaper to build, requires fess engine-room length and has fewer parts to take care of. The size of the cylin- ders was increased by degrees to meet the power requirements' of the larger vessels employed. The largest cylinders so far built by this company are 740 millimeters which in six and eight cyl- inders give respectively 4500 and 6000 indicated horsepower for two screws, turning at 115 revolutions per minute, and suitable for cargo vessels of, say, from 11,000 to 14,000 tons deadweight and 12 to. 12%4 knots speed. The 6- cylinder engine is the same as is being installed by the Cramp company .in the United States shipping board's motor- ship Witl1AM PENN, shortly to be placed in service. It might be mentioned that the same Danish builder has drawings completed for engines having cylinders of 800 millimeters or 3% inches in diameter, . and 500 indicated horsepower per cyl- inder adaptable to intermediate liners. As with the steam engine, there is a limit in size of cylinder for a diesel engine, and it would appear that the 3l¥%-inch is nearing this limit, due principally to liner thickness required. Considerations of convenience for han- dling the parts on board vessel are also involved. It would seem that the next logical step with the 4-cycle engine for increasing the power to more than 500 indicated horsepower per cylinder is to resort to the double acting piston. From the standpoint of elimination of heat troubles, the condition is believed. to be more favorable for the double acting 4-cycle engine than for the single acting 2-cycle engine, as the maximum tem- perature at the first part of the power strokes is alternately distributed to the two ends instead of continually to one end of the cylinder as with the 2-cycle. The adaptability of the motorship in having its auxiliaries electrically driven and the advantages resulting were at the beginning recognized and_ incorporated in the first vessel. As the internal com- bustion engine by nature requires an ex- ternal source of power for starting and