Dern 



IV - CONCLUSION OF SECTION IE - 



Not enough experimental data has been collected for the 

 validity of rolling criterion to be verified without doubt . Neverthe- 

 less this criterion seems reasonable . We must note that it was 

 necessary to introduce in the rolling equation a damping term expe^ 

 rimentally determined for J.N.Newman's theory gives too small a 

 value for this term , and , hence , for the critical values of H 



GENERAL CONCLUSIONS - 



We have shown in sections I and II that J.N.Newman's 

 theory is not valid except if the following conditions are fulfilled : 



a/ - the upper part of the buoy which is normally out of 

 water must be of constant sectional area and must be high enough 

 so as to avoid a double regime in the heaving motion . 



b/ - It is more difficult to state the conditions for avoi - 

 ding rolling motions and unstable pitching motions but lowering the 

 center of gravity is an effective method . 



When these conditions are fulfilled , J.N.Newman's the- 

 ory is well verified except for the values of the maxima of the fre - 

 quency response functions in heaving and pitching . Therefore it 

 seems necessary to determine experimentally the damping terms 

 in heaving and pitching . 



In section III we have proposed a criterion for roll in 

 irregular waves . It seems that the criterion is not in disagreement 

 with the few experimental results which are available , provided 

 that one uses an experimentally determined damping term in the 

 rolling equation . 



1072 



