Pien 



MODEL 4953 



MODEL 4946 



Fig. 13 



Pictures of flow on the after end of 

 Models 4946 and 4953 



reducing form drag. Then the matching main hull is designed by using the wave- 

 making resistance theory to ensure that the combination of the two will produce 

 very low wavemaking resistance. Only in this manner is a bulb effective in re- 

 ducing the total resistance of a ship by reducing the form drag. This may ex- 

 plain the reason why placing a large bulb on tanker models can result in a great 

 reduction in total resistance at relatively low Froude numbers. 



It is believed that the application of wavemaking resistance theory may have 

 more practical value in the reduction of viscous drag than in the reduction of 

 wavemaking resistance itself. From this point of view, the wavemaking resist- 

 ance theory can always be used to reduce the total resistance of a ship regard- 

 less of its design speed. 



1130 



