Naval Architecture and Ship Building 129 



small model and in that way determine the most advantageous form to 

 meet our conditions. For instance, we are building in the United 

 States some large and fast battle cruisers. Some years ago when these 

 were in the early design stages, there were made and tested in the Model 

 Basin at Washington, (which follows the Froude method) upward of 

 twenty possible models for these vessels, with the result that the resist- 

 ance of the model finally adopted was nearly fifteen per cent, less than 

 .that of the first model tried. Since this Model Basin was established 

 a little over twenty years ago we have made and tested for resistance 

 some 2,400 models nearly all of the 20-ft. length. It might seem at first 

 that, with this mass of accumulated experience, the whole ground has 

 been covered. Of course, that accumulated data is of the greatest 

 value, and when a new type of vessel is under consideration we can esti- 

 mate very closely the speed and power without making a model, but 

 when we actually come to the final design stage we still find it possible 

 to make improvements, and regard the work of making and testing 

 several models as essential. 



I might say here that the problem of the naval architect in dealing 

 with actual vessels is not essentially that of making the vessel of the 

 minimum resistance for the displacement. In the case of a given vessel 

 we could nearly always design one of less resistance, but resistance is 

 not the only factor to be considered. For instance, a number of years 

 ago we were investigating the question of a vessel of about four thousand 

 .tons displacement which was required to make a very high speed, or 

 rather a speed very high for those days. We found that if we made this 

 four-thousand ton vessel 450 feet long the resistance would be just half 

 of what it would be if made 350 feet long. Unfortunately for the naval 

 architect, however, length is objectionable from nearly every point of 

 view except that of speed. It involves, for instance, materially greater 

 hull weight because a long vessel is more stressed in a seaway than a 

 short vessel. We finally made the vessel 420 feet long, thus gaining the 

 greater part of the benefit of length without suffering the objections due 

 to excessive length. 



We often find inventors who believe that there is some great merit 

 in some particular shape of line, the merit being lost if the line is varied 

 by a hair's breadth. We find as a matter of fact that the detail shape 

 of lines is rather a secondary feature in connection with resistance. 

 The primary factor in obtaining high speed is length. For low speed 

 vessels, length is less important. Next to length the most important 

 thing is the area of the maximum or midship section as we call it. Details 

 of shape have little influence. The most desirable solution in one case 

 is liable to vary very much from that in another. For instance, for 



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