THE DETERMINATION OF THE RESISTANCE OF SHIPS. PRESENT 



DAY STATUS OF THE ART. 



By Ernest H. Rigg, Esq., Member. 



[Read at the twenty-third general meeting of the Society of Naval Architects and Marine Engineers, held in 



New York, November 18 and 19, 1915.] 



When it was suggested to me that a continuation and extension of the paper 

 I had the honor of reading before the Society in 1912 on "Fuel Economy as In- 

 fluenced by Ship Design" would be interesting and of value, I quite recognized 

 the interest and value of further light on this increasingly important subject, and 

 in reply stated that I feared such a paper would contain very little original mat- 

 ter, but that if the Society would like to have placed in its transactions a review 

 of recent published investigations, together with a review of our present knowl- 

 edge on the subject of powering ships, I should be glad to undertake the task. 

 Such a review can be made of decided value, the transactions thereby becoming 

 so much the more useful to those who design and power ships. This, then, is the 

 object of the paper. 



The subject naturally divides itself into two parts of primary importance, one 

 concerning fine types of ships, and one concerning full types; where the line be- 

 tween the two should be drawn is by no means clearly defined, but, in practice, 

 warships and passenger liners constitute the fine types and cargo steamers the full, 

 with, of course, some exceptions to be found both ways. Motor boats, submarines 

 and hydroplanes are now the subjects of increasing investigation; the usefulness 

 of the two latter types in the great war insures a measure of attention hitherto 

 given only to the larger naval vessels. Published data are already assuming con- 

 siderable dimensions, but there remains, however, plenty to occupy the staffs of the 

 various experimental tanks the world over. 



This paper will deal more particularly with general naval and mercantile 

 types. One of the first things that strikes the reader of the various authorities on 

 this subject is the desirability of a uniform system of notation throughout the 

 technical world. Anyone who can do something to bring this about will have 

 earned the gratitude of all naval architects and naval engineers. 



The lucidity of Taylor's "Manual on Marine Propulsion" stands out as one 

 of the chief merits of the book, practically all fundamental points being covered. 



American writers generally follow the same lines, but, when we read recent 

 and valuable papers written abroad, we naturally find difl^erent systems of notation 

 in use. There is, in practice, danger of serious error in using first one reference 

 and then another, besides the labor of reduction of results from one system to the 

 other, so that anything tending towards an international standard is well worth 

 encouragement and advancement. 



