ALL 95 RECORDS 



50°-95°WIN0 DIRECTION (10 RECORDS) 



130°- 160° WIND DIRECTION (7 RECORDS) 



ot 



0.076 



0.304 0.685 1.22 1.90 



Ratio of Breakwater Width-to-Wavelength, 



2.74 



W/L 



3.73 



4.87 



1 



0.625 



0.750 



0.00 



0.125 



0.250 



0.375 0.500 



Frequency, Hz 



0.875 



1.00 



Figure 47. Average transmission coefficients, Friday Harbor, Washington 

 (after Adee, Richey, and Christensen, 1976). 



than had been anticipated (Adee, Richey, and Christensen, 1976). The natural 

 frequencies of each of the motions were outside the range of significant inci- 

 dent wave energy, and no dominant features were observed in the motion spectra 

 during this field monitoring program. 



b. Canadian Caisson . A floating breakwater denoted as the Canadian 

 caisson type presents a design concept which differs materially from that of 

 most existing or proposed breakwaters. Its dual-intended purpose is not only 

 to protect a harbor from excess wave action, but also to provide a platform of 

 sufficient stability for use as a floating wharf. Experimental studies have 

 been conducted (Western Canada Hydraulic Laboratories Ltd., 1966b) to evaluate 

 the wave damping effectiveness and to measure the anchor chain forces of the 

 Canadian caisson-type breakwater under wave conditions typical of coastal 

 waters. 



The models of the Canadian caisson floating breakwater were constructed to 

 a scale of 1:24. The basic unit of construction was a rectangular pontoon 

 (open on the bottom) , representing a prototype structure 50 feet long by 24 

 feet wide by 8.5 feet deep, divided into 16 compartments, each about 5 by 12 

 feet. All walls were of 6-inch-thick reinforced concrete construction. Two 

 additional units (18 and 36 feet wide) were also tested. The geometry of the 

 24-foot-wide section is shown in Figure 48. The breakwater anchors used by 

 Western Canada Hydraulic Laboratories (1966b) in these studies consisted of 

 lead blocks of sufficient weight to prevent sliding under the most severe wave 

 conditions. The anchor chain length used for these tests was approximately 

 2.5 times the depth of water (about 40 feet prototype), and the chain weighed 

 the equivalent of 14 pounds per foot of prototype length. 



84 



