274 



THEORY OF SEAKEEPING 



Fig. 19 Calculated and measured bending moments at mid-sec- 

 tion restrained 48-ft model of T2-SE-A1 tanker in waves 4.8 ft X 

 3.0 in. (from Jacobs, 1957) 



-J 



TS 



I 



4 



n 



O " c 



-4 

 4 



1^ 2 



^^ 



2.4 Ft/Sec 



r "t^j 



Hydrodynam'ic 

 Loads 



Damping 8c Dynamic Coupling 

 (Velocity - Dependent) 





^"Smith Effect 



" Added !>-~.^ 

 Displacement 



Total 



GO 



50 



40 30 20 



Inches from F. P. 



Fig. 21 Loads on free model of T2-SE-A1 tanker in waves 4.8 



ft X 1.2 in. at 2.4 (fps for condition when wave crest is at FP) 



(from Jacobs, 1958) 



Model I9I9-I- 1958 Regular Wave 

 y Tests for A BS 



-^ . (Long Tank) 



Model I9T5- 1956 Regular Wave 

 Tests for S-3 Panel 

 (Square Tank") 



Model mA^-Oerived from 1954 

 Tests in Irregular 

 Waves for S-3 Panel 



Model 1444-1955 Regular Wave 

 Tests for S-3 Panel 

 Jo. of Ship Research 

 April 1951 



0.5 



1.5 2.0 2.5 



Model Speed, Ft/Sec 



3.0 



3.5 



4.0 



4.5 



10 15 



Ship Speed, Knots 



20 



Fig. 20 Comparison of vertical bending moments from four independent tests. \',oh- 



scale models of T2-SF-A tanker; wave length = model length; wave height = ' /,, X 



model length; head seas (from Lewis, 1958) 



