Field Observations and Measurements 



Installation of the floating breakwater occurred during the summer months 

 of 1982. The tires became so warm during the late summer that feet protection 

 was required when working on the installation. The additional warming of the 

 water by the tires created ideal algae growing conditions. By late fall when 

 the growth subsided the algae completely spanned the open regimes between the 

 tires in several areas of the breakwater. It turned brown during the winter 

 months and resumed growth in April the following year. Figure 19 shows the 

 algae growth that was present two months after installation. 



The breakwater has been a bird sanctuary from the beginning (see 

 Figure 20). The bird population varies from month-to-month with an estimated 

 300 birds having been observed in the structure at various times. 



During the more severe weather months, wave action tends to remove any 

 accumulated rubbish. This generally consists of floating beer or pop cans, food 

 wrappers and sticks or twigs. These have been removed on occasion using a long 

 pole with a ring and net attached at the end. One simply walks up and down the 

 tire-clad tubes scooping up the debris. 



The dynamic response of the tire mazes to wave action has been observed on 

 many occasions. Literally hours have been spent in a boat alongside the 

 breakwater, standing on the cement pier off to the side of the breakwater, and 

 in the observation tower of the municipal water works just aft of the 

 breakwater. Figure 18 was taken from the latter viewing position. Visual 

 observations indicate a significant difference between the two all-truck-tire 

 sections and the one with the car tire maze. Since the tire-clad tubes are 

 relatively stable in the presence of short-wavelength, low-amplitude waves, they 

 serve as a reference for observing the heaving of the maze tires as the wave 

 propagates through the breakwater. Typically a wave which causes observable 

 heaving of the car stringer tires for two-thirds the beam length will appear to 

 be entirely damped out in approximately one-half that distance when working 

 against a truck tire maze. There appears to be little visual difference in 

 attenuation characteristics between the two truck tire maze designs. The PGYM-1 

 front tire stringers seem to heave more at the front edge when encountering a 

 wave front than the PT-1 stringers; however, waves do not appear to propagate 

 into the maze a greater distance. 



Funds for monitoring breakwater performance were severely limited. Even 

 though the instrumentation was sophisticated and data collection was almost 

 automatic, it still required maintenance, supplies, and personnel to operate. 

 As a result, monitoring of the system was only achieved for several storms 

 occurring over a relatively short period of time. The data collected is shown 

 in Figure 21. In Figure 21, C. denotes the ratio of transmitted wave heights to 

 incident wave heights, D is the draft of the floating structure and d is the 

 water depth. The dotted line (D/d = .24) shows the trend of the data relative 

 to the PGYM-2 (car tire maze) sections. The solid line (D/d = .38) indicates 

 the general data trend of the PT-1 and PGYM-1 (truck tire maze) sections. There 

 appears to be little difference in PT-1 and PGYM-1 wave transmission 

 performance. The relative draft of the system does appear to influence the wave 

 transmission behaviour. The transmission coefficient data of the all-truck-tire 

 sections appears to be significantly lower when compared to the car-tire maze 

 sections having less relative draft. This difference showed up on all tests and 

 seems to be in agreement with visual observations. 



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