TWENTY YEARS' PROGKESS IN MARINE 

 CONSTRUCTION.^ 



By Am,xaM)i;k Gkacik, M. V. O., M. int^t. C. E. 



In order lo appreciate fully the progress which has been made 

 during the last 20 years in the design and construction of vessels for 

 the mercantile marine, it will be useful to consider briefly the factors 

 for and against advance, so as the better to realize in what direction 

 forward steps have been and may still be possible. 



The driving forces toward all progress are healthy discontent 

 with what has been done and the satisfaction derived from greater 

 achievement, quite as much as the hope of material gain. The aim 

 of the shipoAvner, the naval architect, and the marine engineer is 

 ever toward increased comfort, speed, and economy. 



Increase in size is undoubtedly the most valuable resource of the 

 naval architect, as it is directly conducive to the attainment of these 

 three desiderata. The greater the length of a vessel in proportion 

 to her total Aveight, the smaller becomes the power in relation to her 

 displacement and speed. Greater size gives more deck space for pas- 

 senger accommodation, greater height above water, and less disturb- 

 ance due to wave motion ; hence, greater comfort. The earning fac- 

 tors, space and displacement, are increased in greater ratio than the 

 cost factors, and thus economy is obtained. 



A concrete example illustrative of these principles may possibly be 

 of interest. I will take the case of a cargo vessel having a speed of 

 13 knots at sea over a 3,000-mile voyage. On a length of 400 feet 

 Ave can construct a vessel Aveighing 3,700 tons Avhich Avould carry 

 4,000 tons of cargo and consume 500 tons of coal. Each 100 tons of 

 cargo, therefore, involves 92^ tons of constructiA'e material and 12^ 

 tons of coal per voyage. A vessel 500 feet in length Avould weigh 

 6,7o0 tons, Avould carry 8,700 tons of cargo, and consume 700 tons of 

 coal. Each 100 tons of cargo in this case requires only 77-| tons of 

 A^essel and 8 tons of fuel. 



The practical success of the large vessel depends, of course, upon 

 the volume of passenger and cargo traffic she can command, and this 



iTIie James Forrest Lecture for 1913, delivered at meetiug of the Institution of Civil 

 Engineers, London, Oct. 23, 1913. Reprinted by permission from " Excerpt Minutes of 

 Proceedings of The Institution of Civil Engineers," vol. 194, session 1912-1913, pt. 4. 



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