in a wave train of 5-foot height and 5-second period. The same maze would dissipate only 

 20 percent of the energy in a wave train of 5-foot height and 10-second period. The maze 

 would require about 150 to 200 tires per foot of crest length. The maze must be anchored 

 in place, but the forces exerted on the anchor lines would not be excessive. Although the 

 tire maze is not effective against waves with periods in excess of about 7 seconds, except at 

 prohibitive cost, it may be practical for harbor sites not exposed to these longer period 

 waves. If practical, the designer should apply the test results of Kamel and Davidson (1968) 

 to the site conditions to determine the proper dimensions and anchorage plan for an 

 effective tire maze. 



Other types of floating breakwaters considered but not tested through long-term use are: 

 (a) an air-fiUed mattress at the surface or suspended at some distance below the surface to 

 achieve out-of-phase damping, (b) a thin membrane on the surface to achieve viscous 

 damping, (c) random arrangements of horizontal pipes to destroy orbital wave motion, (d) a 

 series of vertical diaphragms to accomplish the same effect, and (e) various types of soUd 

 structures with void patterns designed to break up wave action in one way or another 

 (Fig. 40). Although the search continues, none of these types has yet given promise of being 

 a practical solution to long-period wave dissipation. 



Figure 40. Floating corrugated metal pipe breakwater, Detroit Harbor, Michigan. 



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