outside leading the inside gage by approximately 180° over the fre- 

 quency range of 0.25 to 0.37 hertz. This indicates that the forces are 

 relatively uninfluenced by waves above approximately 0.37 hertz. This 

 frequency range is also where the transmission curves rise to near 

 unity. This agrees with the low- frequency analysis and suggests that 

 the response is similar over the complete frequency range below 0.37 

 hertz. 



The acceleration force, autospectral and cross-spectral analysis 

 results, are also given in Appendix J for the higher frequency range for 

 record FH 7-8. No dominant features were observed in the motion spectra. 

 Their peak values and spread of energy with frequency appear to follow 

 the general character of the incident wave spectra in all records ana- 

 lyzed. This implies that any natural frequencies in each of the motions 

 is outside the range of significant incident wave energy. The cross- 

 spectral analysis shows a high coherency and zero phase shift between 

 the heave and roll accelerations. In both the sway and roll, and the 

 sway and heave accelerations, the sway acceleration leads by approxima- 

 tely 180° over the range of significant incident wave energy and then 

 tapers to near- zero phase shift at higher frequencies. Also, the cohe- 

 rency is high enough over the incident wave energy band to imply near 

 linearity between all three motions. 



These conclusions are based on positive sway being outward from the 

 short leg (south) , heave positive up, and the positive roll to be clock- 

 wise around a positive axis pointing westerly toward shore. 



63 



