1) The study of the three-dimensional correction is fotind to be 

 rather significant. Therefore practical correction factors must be developed 

 for prediction of ship motions. 



2) The effects of the dynamic lift on the hull should be examined 

 experimentally and theoretically. 



3) Investigations should be performed with regard to non-linear effect 

 including the displacement effect, etc. Both theoretical and experimental 

 studies should be the basis of this investigation. 



Further Investigations 



1) Combined action of steady and unsteady excitation: 



The equations of motion, which are now in use, are valid in the 

 frequency domain, and therefore, if there is also a steady force, for example, 

 wind, rudder and drift forces, acting on the ship, these equations are no 

 more useful. 



2) Low frequency motions: 



As it is well-known, even for the heaving motion, the results for 

 low frequencies may not be realistic. A knowledge in the low frequency range 

 is generally very important, especially for the prediction of lateral motions 

 (i.e. sway, roll and yaw) in following waves, because of intact and course- 

 keeping stability of ships. From its basic assumption it is clear that the 

 strip theory may not be suitable for this purpose as t hree-dimensional effects 

 as well as viscous effects will be significant. 



3) Impact pressures: 



Determination of pressures during slamming is important in avoiding 

 bow damage and in determining the hull bending moment and springing. The theo- 

 retical results are still not satisfactory because of various simplifications 

 made in the problem formulation. 



Since' a solution which should consider the effects of compressibility, 



83 



