1.5 0.6 0.7 0.8 0.91.0 2.0 3.0 



Stress Variation- Kips/Inch^ 



5.0 6.0 7.0 8.09.010 



Fig. 18 Cumulative "Long-Term" Distribution of Wave-Induced, Hull-Girder Stresses for Several Ships 



tion of all trips vsfhich, on the average, are ex- 

 pected to give an extreme value of the stress less 

 than X. On the bottom scale, values of 1/(1 — 

 F), denoted by T, are shown; T is the number of 

 trips the ship must make, on the average, in order 

 to exceed the limit during at least one of the 2- 

 min sampling periods. The dashed confidence 

 limits drawn in Fig. 17 denote the limits within 



which 67 per cent of the experimental data would 

 be expected to fall if measurements of extremes 

 were conducted indefinitely and if the assumed 

 distribution were valid. Inasmuch as the scatter 

 lies well within these limits, it is concluded 

 that, for the service conditions encountered, the 

 extreme-value distribution (from hourly 2-min 

 samples) of the sea-induced hull-girder stresses 



28 



