EESISTANCE OF SHIPS 



397 



to the stern, and is due to flow in what is in effect a channel with 



diverging boundaries. Mr. Froude, 



in his experiments, found it necessary 



not only to use a cutwater, but also 



to taper off the stern of his planks in 



order to get a resistance length 



curve, which should pass through the 



origin of co-ordinates, the effect being 



as indicated in Fig. 181. 



As a factor in reducing resistance 

 in fact, a finely tapered stern or run 

 is of much greater value in a ship- 

 shaped body than is a fine stem. With 

 a model as shown in Fig. 182, the 

 directions of motion for least and 

 greatest resistances are as indicated. 



L e ncj th 

 FIG. ~181. 



Experiments by Stanton l on the 

 resistance of models having one end 

 hemispherical and the other conical, give the following values of 

 relative resistance R. 



the 



Taking S to be the projected area of the stern, the reduction in 



1 " Transactions In-st. Naval Architects," 1909, 



