LOADS ACTING ON A SHIP AND THE ELASTIC RESPONSE OF A SHIP 



273 



■Theorg_lic2J_y{2y^_ 



Profile 



Weight Corrected for 

 Absolute Model Acceleration 



Buoyancy Corrected to give Shear 

 and Bending Moment Equilibrium 



10 Stations 9 



7 6 5 4 



Weight and Buoyancy Curves 



Model Vertical Acceleration 

 Relative to Wave' 



Model Vertical Velocity 

 Relative to Wave 



Velocities and Accelerations 



60 



2^ 



Fig. 18 Bending-moment calculation including dynamic eflfects, at speed corresponding to 14'/-knots. T2-SE-A1 tanker model in 



hogging condition, regular L/20 head seas (from E. V. Lewis, 1954) 



Ochi's results are in qualitative agreement with Schiui- 

 del's (MS San Francisco) and Lewis' data in that the 

 sagging moment is larger than the hogging one. Quan- 

 titatively, however, there are large differences. Schna- 

 del found the sagging moment to be some 20 per cent 

 larger than the hogging one. Lewis' Figure 14 shows the 

 sagging l)ending moment to exceed the hogging one by 

 about 30 per cent. Ochi's Fig. 25, on the other hand, 

 shows the hogging stress at zero speed of about 0.115 

 kg/mm- while the sagging stress is almost 0.2 kg/mm-, 

 or 74 per cent larger than the hogging one. 



Ochi adopted Schnadel's definition of the "effective 

 wave height" as the height of a wave which, lay con- 

 ventional static calculations, produced the same stress 

 as the actual wave. He called the "effective wave 

 height ratio," rj," the ratio of the height of this static 

 wave to the actual wave height. He made static cal- 

 culations alternately on the basis of the displacement 

 and the displacement with correction for the Smith effect. 



" With subscripts H for hoggins, .s for sagging, and primes 

 denoting computations made with Smitli effect taken into account. 



