TABLE 6 



Basic Statistical Data on Heave Accelerations 



Sea 

 State 

 (Est'd) 



Significant 

 Wave 

 Heigtit 



ft 



Heading of 



Waves Relative 



to Sfiip 



Sliip 

 Speed 



knots* 



,V 

 Number of 

 Variations 

 per Hour 



Minutes 

 Sampled 



E 

 g.32 



Predicted 



Maximum Value 



for 1-hr 



Operation 



E's 



Maximum Measured 



Peak-to-Peali 



Variation 



8's 



Number of Variations 



in Sample 



from Whicfi 



Maximum Was Obtained 



Predicted 



Maximum 



Peak-to-Peak 



Variation 



Ratio 



Predicted 



Maximum to 



Measured Maximum 



3 



7-3 



Head 

 Seas 



10 

 14 

 17 



448 

 590 

 582 



26 

 32 

 27 



0.0107 

 0.0186 

 0.0221 



0.252 

 0.35 

 0.37 



0.26 

 0.32 

 0.37 



239 

 315 

 262 



0.251 

 0.321 

 0.35 



0.97 

 1.01 

 0.95 



5 



21 



Head 

 Seas 



7 1/2 

 10 

 14 



433 

 518 

 514 



27 



27 



24 1/2 



0.0221 

 0.0272 

 0.0382 



0.37 

 0.41 

 0.49 



0.51 

 0.41 

 0.49 



197 

 233 

 210 



0.341 

 0.385 

 0.451 



0.67 

 0.94 

 0.92 



5 



21 



Quarter 

 Head 

 Seas 



7 1/2 

 10 

 14 



466 

 583 

 565 



38 1/2 



28 

 27 1/2 



0.0182 

 0.0245 

 0.0498 



0.33 



0.40 

 0.57 



0.29 

 0.44 

 0.62 



299 

 272 

 259 



0.322 

 0.371 

 0.525 



1.11 

 0.84 

 0.85 



5 



21 



Beam 

 Seas 



7 1/2 



433 



28 



0.0143 



0.29 



0.26 



202 



0.276 



1.06 



5 



21 



Quarter 



Following 



Seas 



7 1/2 

 10 



14 



418 



552 

 504 



32 

 30 

 27 



0.0147 

 0.0131 

 0.0135 



0.30 

 0.29 

 0.29 



0.35 

 0.34 

 0.32 



223 

 226 

 227 



0.282 

 0.267 

 0.270 



0.81 

 0.78 

 0.84 



♦The speed is the nocninal speed read from a calibration curve of propeller rpm versus knots; 

 7 1/2, 10, 14, and 17 knots correspond to 94, 127, 185, and 230 rpm, respecUvely. 



TABLE 7 



Constants Required for Prediction of Probable Maximum Value 

 in a Sample from a Rayleigh Distribution 



Let X be the most probable maximum value of x taken from a sample containing N values of x. Then, 



max _ 



according to Longuet-Higgins" x = \fW\J E where - log^ N - log^ 1 (l — e"*^ ) I . For large N, 



e = log„ N. 



Sample Size 



^ 



Sample Size 



vr 



N 





N 





1 



0.707 



1000 



2.642 



2 



1.030 



2000 



2.769 



5 



1.366 



5000 



2.929 



10 



1.583 



10,000 



3.044 



20 



1.778 



20,000 



3.155 



50 



2.010 



50,000 



3.296 



100 



2.172 



100,000 



3.400 



200 



2.323 







500 



2.509 







15 



