TABLfij 12 - Maximum Values of Ship Motion and Longitudinal Bending Moment 

 for Use in Design Calculations 



All values given refer to the peak-to-peak variation. 



Quanti'> 



Condition for Which the Extreme Value is Predicted 



V 



Number of Variations 



in 12 Hours 



for Steady 



Conditrons 



a Vi $ >- 



l.(aximum Variation for 



Operating Life 



of Ship 



/= 0.001 



flj c Ci 

 If = 



1 1 



E « 



Sea 

 State 



Significant 

 Wave Height 



Direction 

 of Seas 



Shaft 

 RPM 



^. 



Roll Angle 



5 



21 



QF 



94 



176 (deg)2 



4600 



39° 



56° 



50° 



56° 



Pilcti Angle 



5 



21 



H 



1B5 



56 (deg)2 



7000 



22° 



32°^^ 



20° 



about 25° 



•Roll Angle 



S 



21 



QF 



94 













40° 



•Pitch Angle 



5 



21 



QF 



94 













10° 



Pitch Acceleration 



5 



21 



QH 



185 



0:0327 (rad/sec^)^ 



8500 



0.54 rad/sec^ 



0.78 rad/sec^ 



0.77 rad/sec^ 



0.8 rad/sec^ 



Heave Acceleration 



5 



21 



QH 



185 



0.0498 (gravity unit)^ 



6800 



0.66 g 



1.0 g 



1.0 g 



1.0 g 



Longitudinal Bending 

 Moment 



5 



21 



H 



185 



85xlO^(fl-tons)2 



9500 



28,000 ft-tons 



40,000 ft-tons 



33,000 ft-tons 



40,000 ft-tons 



Longitudinal Bending 

 Stress 



5 



21 



H 



185 



3.50 (kips/in2)2 



9500 



5.7 kips/in^ 



8.0 kips/in^ 



6.7 kips/in2 



8.0 kips/in^ 



•This iB beUeved to be a moBt severe condition of simultsneous roll end pitch. The data are taicen from Figure 5b of Reference 2. 

 ••This estimate (32°> is believed to be outside the range within which the statistical estimation ia valid and therefore the value is discarded. 



fTheso values are nearly the largest magnitudes obtained under anv conditions experienced during the teats reported in Reference 2. 

 QH - QusTter FoUowing: QF - Quarter Head; H - Head 



Maximum estimated values for the other variables have been computed similarly, taking 

 / = 0.001 and n = 10. They are listed in Table 12 together with the largest values measured 

 at any time during the rough water sea trials reported in References 2 and 6. We will take 

 the larger of the statistically estimated and the measured values as the suggested maximum 

 value to use for design purposes. 



For some design problems, it is necessary to make an estimate of the extreme condi- 

 tions of simultaneous pitch and roll. It is unlikely that the maximum conditions of pitch and 

 roll listed in the last column of Table 12 will occur simultaneously. The most severe combi- 

 nations of simultaneous roll and pitch angle, measured during the sea trials,-^ was 40 deg 

 double amplitude in roll together with 10 deg double amplitude in pitch, see Table 12. It is 

 suggested that this combination be used as an extreme condition for design purposes. 

 Predicted extreme values should be used with caution because the method eventually breaks 

 down by predicting too extreme a value. This occurs because, in practical application the 

 theoretical distribution cannot be relied upon at the extreme ranges of the function. For ex- 

 ample, the prediction of 32 deg -for the extreme value of pitch angle variation is probable 

 unrealistic as nonlinear behavior of the pitch motion will probably set a lower limit than this. 



The extreme values listed in the last column of Table 12 may be used to set an interim 

 upper limit to the validity of predicted extreme values. 



DESIGN LOADS FOR BOTTOM STRUCTURE TO WITHSTAND SLAMMING LOADS 



A detailed analysis of the loads, stresses, and deflection for the bottom plating of an 

 AVP vessel incident to slamming has been made by Greenspon.^ On the basis of the latter 



26 



