In case of advancing ship [29] found three-dimensional correction 

 factor for each coefficient of the equations of motion of the ordinary strip 

 method by the thin ship theory of [ ] , In addition they corrected the co- 

 efficients of the equations of motions using the assumption of the slender 

 body to which normal ships are subjected. The calculated results of the 

 said three-dimensional effect, together with the results as mentioned above, 

 are illustrated in Fig. 1 and 2 which show that the three-dimensional effect 

 is rather significant. Thus, it is necessary to consider this effect in 

 ship motion calculations. 



Also one should be careful in obtaining the longitudinal derivations 

 of the two-dimensional (sectional) added mass and damping coefficients as 

 these may cause significant errors in the calculated force distribution for 

 a ship with forward speed. One should therefore adopt a smoothing procedure 

 before the numerical derivation. 



For critical reviews of strip theories one should refer to [30 ] and 

 [48]. 



In order to overcome some conceptual and practical shortcomings of 

 the strip theory various attempts have been made to include the effects of 

 three-dimensionality . 



However, calculations have shown that these corrections did not pro- 

 vide an improved accuracy. In fact, in most of the cases the predictions 

 become worse when the three-dimensional corrections were applied. Only the 

 technique proposed by [10] may be acceptable. This method proposed an interest- 

 ing quasi-three-dimensional method which, however, did not receive wide ac- 

 ceptance because of the more complicated calculations needed. 



After investigations of all the topics as mentioned above, [29] made the 

 following observations: 



81 



