1.2 





h 

 c 



Bad sea / 

 Dndition 1>^/ 



I 





\ 



\ 



J 1 



\ 



\ 







v_ 



ly 





\ 







\\ 







beam sea 

 condition 



A 



. 





\ 



\ 





^ 





head anc 

 seas, con 



beann >>. 

 dition 4 "^"^N^ 



^ 





0.2 



0.8 



0.4 0.6 



Frequency (sec ) 

 Figure B-16. Heave response of FORDS in regular waves of small amplitude. 



The axial forces imparted in the string for test condition 1 are 

 particularly significant; they are comparable to what can be expected in a 

 ship of around 13,000 tons displacement. For a ship heading directly into a 

 sea state 6, the dynamic forces are 1 7% of the static forces; for a sea state 4 

 the same heading will result in dynamic stress 10% of the static. The latter 

 is more realistic. 



134 



