Application of Wavemaking Resistance Theory- 



Fig, 10 - Body plans of Models 4946 and 4953 



It is obvious from the foregoing that if water is prevented from flowing 

 across the bilge, as in the case of Model 4946, formation of eddies can be 

 avoided. However, the round bottom of Model 4946 is not practical, and we have 

 to search for other means. A sizable bulb can be used for such a purpose. 

 Starting from the stagnation point, the water can be guided in all directions by a 

 bulb, so that it is properly channeled toward the flat bottom from the very begin- 

 ning rather than spilling over the bilge to reach the bottom at a later stage. 



A bulb can be used in this way to prevent the formation of eddies and thus 

 reduce the form drag. However, the total resistance will not necessarily be re- 

 duced. If not properly matched to the main hull form, a bulb will produce a 

 large wave drag, and any gain in form drag may well be exceeded by the penalty 

 of wave-drag increment. Again the wavemaking resistance theory can be used 

 to great advantage in this situation. To start with, we may choose a proper 

 sized bulb and place it at a correct location based on the consideration of 



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