6 THE INTERNAL-COMBUSTION ENGINE 



Of other continental builders who have done much also to promote development of 

 the motor ship with their respective designs may be mentioned Werkspoor, Sulzer, Ansaldo 

 San Gorgio, Krupp, Polar Diesel and Vickers of England. 



A brief review of Burmeister & Wain's work in this field will be given as best illus- 

 trating the development of the art. This maker, like Werkspoor, has always held to the 

 four-cycle engine as best suited to this class of service, where utmost reliability combined 

 with economy is of first consideration. 



Their epoch-making first vessel, the Selandia, was put into service in February, 1912, 

 being 7,400 tons deadweight, having twin screws, and designed for 10j4 knots. The two 

 main engines, which have eight cylinders each, develop 2,500 total indicated horse-power when 

 running at 140 revolutions per minute. This vessel, now entering her tenth year, with a 

 total mileage of nearly 500,000', has proven the same unqualified success as her successors 

 and is today in steady service in the Far Eastern trade, while hundreds of steamships com- 

 pleted eight years later are laid up on account of their greatly inferior operating economy. 

 Eight cylinders were used to limit the diameter to 530 mm., or 21 inches, which was the 

 same as Burmeister & Wain's largest land engine at that time. Later the number was 

 changed to six, which is cheaper to build, requires less engine-room length and has fewer 

 parts to take care of. The size of the cylinders was increased by degrees to meet the power 

 requirements of the larger vessels employed. The largest cylinders so far built by this com- 

 pany are 740 mm., which in six and eight cylinders give respectively 4,500 and 6,000 indi- 

 cated horse-power for two screws, turning at 1 1 5 revolutions per minute, and suitable for 

 cargo vessels of, say, from 11,000 to 14,000 tons deadweight and 12 to 12 J4 knots speed. 

 The six-cylinder engine is the same as is being installed by the Cramp Company in the United 

 States Shipping Board's motor ship William 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 mm. or 31 J4 inches diameter, and 500 indicated horse-power per 

 cylinder 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 3 1^^ -inch is nearing this limit, due principally to liner thickness re- 

 quired. Considerations of convenience for handling the parts on board vessel are also in- 

 volved. It would seem that the next logical step with the four-cycle engine for increasing the 

 power to more than 500 indicated horse-power 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 four-cycle engine than for the single-acting two- 

 cycle engine, as the maximum temperature 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 

 two cycle. 



The adaptability of the motor ship in having its auxiliaries electrically driven and the 

 advantages resulting from the same were at the beginning recognized by Burmeister & Wain 

 and incorporated in their first vessel. As the internal-combustion engine by nature requires 

 an external source of power for starting and maneuvering, the same power can be effectively 

 used for other purposes as for driving pumps in engine-room and deck machinery. The sav- 

 ing in fuel thus made, being about one-tenth that of a steam vessel when in port, it should 

 be observed, is due primarily to the efficiency of the Diesel engine driving generators and 

 not so much to the electrical transmission as some have been led to assume. 



In the earlier installations two large auxiliary engines were used, each driving a genera- 



