The example (Table 2) indicates that wave height is reduced 12.5 percent 

 by the field for a 2.6-second wave period. Table 1 (col. 5) shows 

 some wave height attenuation factors greater than 1 which implies a 

 gain in wave height at the landward gage due to the presence of the 

 field. Such a condition is impossible and indicates noise in the ex- 

 periment . 



To provide a check on the wave height attenuation factor calcula- 

 tions, the segment of the wave record from which the wave height was 

 calculated was digitized at a rate of two times per second. From the 

 digitized data the variance of the wave record v.fas calculated; the 

 variance is proportional to the wave energy. Thie variance of each 

 wave record was treated the same as the wave height in Table 2 to give 

 a wave energy attenuation factor for each condition (Table 1, col. 6). 

 The square root of the wave energy attenuation factor (Table 1, col. 7) 

 can be compared to the wave height attenuation factor as a method of 

 judging the consistency of the two methods in evaluating wave attenuation 

 due to the seaweed field. Both methods indicate that with the exception 

 of the shortest wave period, there is little wave energy loss. 



To further document the attenuation for the shortest period, T = 2.6 

 seconds, an analysis of a longer record length was conducted. Because 

 of the slower group speed of this wave period a considerably greater 

 record length and number of waves were unaffected by reflection from the 

 absorber slope than for the longer period wave conditions. An analysis 

 based on the first 25 stable waves unaffected by reflection gave a wave 

 height attenuation factor of 0.878. The same segments of records used in 

 the 25 wave analyses were digitized two times per second and gave a wave 

 energy attenuation factor of 0.791 which corresponds to a wave height 

 attenuation factor of 0.889 (Table 1, cols. 5, 6, and 7). 



IV. CONCLUSION 



This study shows that for the width of the field tested, the low 

 specific gravity artificial seaweed is not effective in attenuating 

 wave energy at wave periods commonly found in the ocean or other large 

 bodies of water. 



