306 THE INFLUENCE OF SHAPE OF 



of the merchant ship type and at speed-length ratios over .75 and not exceeding, say, 1.0, 

 the U-shaped bow sections accompanied with moderately V-shaped sections aft, i. e., sections 

 not too full on the waterline, will in general give good results. 



In the fuller types and at speed-length ratios in the neighborhood of about .6 or under, 

 the V-shaped bow sections, accompanied with moderate stem sections as above, will, in the 

 majority of cases, give a satisfactory form. 



If it is anticipated that the vessel is to run at reduced draught for any appreciable per- 

 centage of her time, then the U-shaped bow sections lose their advantage, and a compromise 

 section will prove more satisfactory. Oil-carrying vessels and Lake ore carriers are an illus- 

 tration of the case where the vessel runs for 50 per cent of its time at a considerably reduced 

 draught. 



The underlying cause of the variation of resistance due to shape of section is probably 

 to be found in the general conditions of stream-line flow at the ends, so that the prismatic 

 coefficient of the ends, combined with the speed-length ratio of ends and also what might 

 be called "diagonal fineness," will influence the results. Admiral Taylor's experiments on 

 stream-line flow around vessels show conclusively that a good deal of the general flow is 

 in a downward direction and, consequently, anything that can be done to make the path as 

 easy as possible ; i. e., by paying some attention to the lower parts of the sections, particu- 

 larly where these fair into the midship part, will probably reduce resistance. 



