Yim 



H~ 



FROUDE NUMBER 

 Fig. 7c - Bow wave resistance of the hollow ship 



There are many side problems even with the bulbous bow alone, i.e., spray, 

 slamming, cavitation, form drag due to separation, etc. In this respect, the 

 bulb made of a source line for a hollow ship seems to be more favorable than a 

 doublet bulb, especially for lower Froude numbers, since the source bulb will 

 not produce any marked swan neck shape. It may be worth noting here again 

 that the bulb is not necessarily made of a doublet, but it can be a concentrated 

 source at the bow near the keel, or a doublet plus a source or a quadrupole de- 

 pending upon the original hull shape. 



Of course it is possible to consider the adjustment of the location of bulbs 

 instead of considering only the shapes of bulbs with a fixed location. However, 

 in this case, it is not easy to find the best location from the theory of wave can- 

 cellation only, since cancellation of elementary waves in one direction of propa- 

 gation does not mean that cancellation occurs in the other directions. Yim (1962) 

 considered a most simple case of a point source and a doublet in a uniform 



1084 



