EXPERIMENTS ON THE FULTON AND THE FROUDE. 



By Professor C. H. Peabody, Member op Council. 



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



New York, November 21 and 22, 1912.] 



PRBlvIMINARY. 



The objects of the experiments related in this paper are the investigation 

 of the characteristics of tow-boats and the determination of favorable condi- 

 tions. The applicability of steamboats for towing was so evident that forms 

 and proportions were settled early in the history of steam navigation, being 

 controlled, in part, by the ideas then prevalent concerning the action of screw- 

 propellers and in part by the conditions of service which required simplicity 

 and reliability in the hands of men economically available for boats of that 

 class. The conditions of the service favor conservatism, and consequently 

 the early types have been generally preserved, though there are instances of 

 progressive designs that have broken away from tradition, especially for 

 large seagoing tow-boats. The propellers used for tow-boats have habitually 

 been fotur-bladed, with large area and wide tips, and have had a large pitch- 

 ratio, commonly from 1.3 to 1.5. The pitch-ratio is controlled by the use of 

 relatively slow engines, and the form of blade according to the old ideas con- 

 cerning the action of screw-propellers, especially as appUed to towing. Many 

 designers have been of the opinion that both width of blade and pitch-ratio 

 could advantageously be reduced and, when circumstances appeared favor- 

 able, have made such changes. 



During the experiments made in the summer of 191 1 on the Froude 

 with propellers having various pitch-ratios and widths of blades, advantage 

 was taken of the opportunities to make experiments in towing and pulling; 

 these experiments could not be reduced in time for presentation with other 

 results, which is not to be regretted, as they can conveniently be presented 

 here in connection with experiments on the Fulton, which is a typical harbor 

 tow-boat made to one-third the size of its prototype the Sotoyomo, for which 

 data are given by Naval Constructor D. W. Taylor, U. S. N., in the fifteenth 

 volume of our Transactions. Speed trials were made of the Sotoyomo in 

 1907 near Mare Island Navy Yard, the model was towed in the Model 

 Basin, and results of these investigations have been kindly furnished to me 

 by the Chief Constructor, Admiral R. M. Watt, U. S. N. 



