Design Source: The builder utilized design literature from the University of 

 Rhode Island. 



Construction: This FTB is 243.8 m (800.0 ft) in length with half the structure 

 10.7 m (35.0 ft) wide and the remainder 6.4 m (21.0 ft) wide. Primary 

 flotation relies on air trapped in the tire crowns. Rubber conveyor 

 belting fastened by bolts is used to couple the tires. 



Site: 









:\ 





1 1 1 



^ FTB 



PORTLAND 

 HARBOR 





A 





1 1 1 1 1 

 1 1 1 1 1 



H 



Mill 







1 



100 



— 1 



200m 



Installation: The breakwater is tied to pilings by rubber conveyor belting. 

 On the structure's exposed side, the pilings are spaced 15.2 m (50.0 ft) 

 apart and on its leeward side, 30.5 m (100.0 ft) apart. 



Field Experience 



Operation: Piling failure posed the first moderate problem to the operation of 

 this new breakwater. In response, the operator removed the old pilings, 

 drove ne_w ones and added greater slack in the mooring connections between 

 the modules and the pilings. Ice damage to the pilings contributed to 

 this failure and represents a minor problem. Fouling growth is also 

 considered a moderate problem, resulting in minor trouble with buoyancy. 

 Under typical storm conditions with waves 0.9 m (3.0 ft) in height and 

 18.5 m (60.7 ft) in estimated length, the transmission coefficient is 

 0.33. 



Maintenance: 

 month . 



Scheduled maintenance consists of checking for sunken tires each 



Cost: The total construction cost for this breakwater was $20,000. This 



figure translates to a cost of $9.59/m 2 ($0.89/ft 2 ). Repairs due to storm 

 damage over the past year required $2,000. 



Benefits: The operator felt that the breakwater had a positive effect on 

 boaters' comfort and on drawing birds away from his facility. He also 

 noted that the structure had improved public relations for the marina. He 

 rated the FTB as providing moderate performance in suppressing waves, 

 meeting design goals, and satisfying his needs. Overall performance was 

 rated moderate. 



40 



