curve of the so-called pressiire response factor from which cut-off values 

 may be determined. The cut-off value is defined as that value of U, 

 at which there is a two-percent response of the pa-imal wave, or the fre- 

 quency at which the power is essentially zeroo A set of such theoretical 

 curves, \^=./\ (/A/ jl^(/(,'^ constructed for various values of the parameters 



I =onr/w. and a is shoiTO in figiu-e 1„ It is to be noted that the defini- 

 tion of the response factor is independeTst vjhether wave height or wave 

 amplitude is used since the linear relationship, wave height equals tvjice 

 the wave amplitude, is assumed to holdo 



Although a completely analytic solution of equation (l) is not possible. 

 it can be solved numerically for any given depth, X^fith ^io) determined 

 from a wave-staff record and K given by equation (2), Ap(/<-"i can be 

 determined o 



A set of data consisting of surface wave height measurements was 

 used to obtained a surface power spectrum A (/Al) • ^°^ ^^^^^ P-irpose, 

 values pC-tO ■^^e^® taken off of a 20-minute wave-staff record at inter- 

 vals of A't- 9. seconds. These values were used to solve Tukey's chain 

 of equations (Pierson, 19^2) as follows: 



(4) 



m-\ 



L^ = I /yy\ (Qo+a^ Qp tosUpkM4-Q^<loS-nU 



