Ship Waves 425 
curves which correspond to curves A, B and C of fig. 3 below, and the 
mutual relations of the three curves in the two cases have much in common. 
6. In the preceding work, the reducing factor has been given specially 
simple forms in order that the calculations might be made in terms of 
functions which have already been tabulated. However, for the wave 
resistance of a model of ordinary form and draught, the calculations are 
usually made by numerical and graphical methods for the particular 
case; the introduction of a reducing factor of suitable form would not 
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c/V (gl) 
Fic. 3 
add any great complication. The usefulness of such a factor would 
depend largely upon whether it proved to be sufficiently independent of 
speed and of variation of form of the model. 
SUMMARY 
The main effect of fluid friction in regard to the production of waves 
by a ship may be described as a decreasing efficiency of elements of the 
ship’s surface with increasing distance from the bow. A reducing factor, 
406 
