Applying Results of Seakeeping Research 



foredeck immersion. It also shows a big advantage of L/H = 17.5 over l/h = 

 11.0. In all cases bow freeboard is 9% of length. 



Considering the question of forefoot emergence, Fig. 9 shows again a dis- 

 advantage in speed. Conversely, it shows that slowing down will always amelio- 

 rate the situation. However, it also shows a distinct disadvantage for a slender 

 ship with high L/H value. This is because, although the shorter ships have 

 more relative bow motion, their greater draft serves to reduce the frequency of 

 bow emergence. Definite conclusions regarding slamming cannot be drawn, 

 however, because the form of the more slender ships involves less flat of bot- 

 tom and therefore less tendency to slam when the bow does emerge. Further 

 investigation is clearly needed, but the calculation procedure described does in- 

 dicate the trends of forefoot emergence. 



Finally, the effect of ship heading can be considered. Figure 10 shows the 

 trend of relative bow motion with ship heading for the case of one particular 

 ship at one speed. The improvement shown in behavior as the bow falls away 

 from the sea is to be expected, but it is perhaps surprising to see such smaU 

 changes for all headings between a beam and a following sea. 



45 90 135 



HEADING (DEGREES) 



Fig. 10 - Relative bow motion effect of 

 heading in Pierson 62-knot spectrum 

 series 60, Cg = 0.70 ships 



205 



