Evaluation of Motions of Marine Craft in Irregular Seas 

 NOMENCLATURE 



A(cj) modulus of transfer function 



(p(aj) phase angle of transfer function 



^(o)) complex transfer function 



P(co) real part of complex transfer function 



0(0)) imaginary part of complex transfer function 



t real time 



t,t' dummy time variable 



CO circular frequency of wave, radius/sec 



co^ natural frequency of physical system, radius/sec 



^ distance in horizontal direction 



^ distance in vertical direction 



^ ' damping ratio of oscillating system 



Vo surface wave amplitude 



7] amplitude of wave orbital motion at depth 



h depth to center of vertical fin on submerged body 



S(t) Dirac delta function 



amplitude of roll motion, radians 



z(t) time history of vertical motions 



^(t) time history of angular motions 



REFERENCES 



1. St. Denis, M. and Pierson, W. J., "On the Motions of Ships in Confused 

 Seas," The Society of Naval Architects and Marine Engineers, Vol. 61, 1953. 



2. Fuchs, R. A. and MacCamy, R. C, "A Linear Theory of Ship Motion in Ir- 

 regular Waves," Institute of Engineering Research, Wave Research Labora- 

 tory T.R. Series 61, Issue 2, University of California, Berkley, California, 

 July 1953. 



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