Construction: This FTB was 61.0 m (200.0 ft) in length and 17.1 m (56.0 ft) in 

 width. Primary flotation relied on air trapped in the tire crowns. 

 Rubber conveyor belting fastened by bolts was used to couple the tires. A 

 volunteer work force was used to build the breakwater and this resulted in 

 inconsistent and poor-quality construction. 



Site: 



LAKE ERIE 





\ Fixed Steel 





Fixed Steel^ 

 Breakwater^ 



A,c h ora g e 



Vftb 



BARCELONA 

 HARBOR 



I 1 1 



SO 100m 







^ == ^X T 



Installation: The breakwater was anchored to 1,634-kg (3,600 lb) concrete 

 blocks. On the structure's exposed side, the blocks were spaced 4.3 m 

 (14.0 ft) apart and on its leeward side, 8.5 m (28.0 ft) apart. Mooring 

 lines were of chain and were 12.2 m in length. 



Field Experience 



Operation: Inadequate buoyancy was an extreme problem, as was litter 



entrapment. Presumably, large amounts of silt were trapped in the tire 

 bases and this factor, when combined with the nominal flotation available, 

 caused the sinking of the structure. Fouling growth was cited as a 

 moderate problem. Finally, a host of troubles were listed as being 

 relatively minor and inconsequential problems. These included structural 

 failure, collision damage, interference with boating traffic, ice damage, 

 anchoring system failure, mooring-line failure, and coupling failure. 

 Under typical storm conditions with waves 1.2 m (4.0 ft) in height and 

 17.0 m (55.8 ft) in estimated length, the transmission coefficient was 

 0.50. 



Cost: Construction materials cost $8,000; labor cost was $2,000. In 

 stallation was an additional $500. These figures translate to an 

 overall cost of $11.46/m 2 ($1.06/ft 2 ) in 1980 dollars. Disposing 

 of the FTB was $5,000. 



Benefits: The operator regarded this project as a completely negative 



experience. He felt the FTB was totally ineffective in suppressing waves, 

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

 rated ineffective. 



Project Analysis: Obviously, this project had severe buoyancy problems. 



Reserve flotation, such as that provided by poured polyurethane foam, 

 should have been included. Maintenance should also have been scheduled. 

 In this case, the most effective maintenance would have been regularly 

 blowing compressed air into the structure. One interesting observation by 

 the operator was the poor craftsmanship seen resulting from the use of 

 volunteers, indicating the advantages of a paid, professional work force. 



46 



