Construction: The original FTB was 182.9 m (600.0 ft) in length and 8.5 m 



(28.0 ft) in width. This FTB's flotation relied solely on air trapped in 

 the tire crowns. Stainless- steel wire was used as the coupling material. 

 When reconstructed, the FTB was extended to 304.8 m (1,000.0 ft) in length. 

 Polyethylene blocks were inserted in the tires to aid flotation and open 

 link Campbell chain replaced the stainless-steel wire. 



Site: 



LAKE ERIE 



Offshore Breakwater 



Installation: The breakwater was initially anchored by 24 cylindrical- 

 shaped 272-kg (600 lb) cement blocks. These were found to roll on 

 the bottom during strong wave action and so were replaced by a like 

 number of rectangular- shaped cement blocks. Mooring lines were of 

 chain and were 19.5 m (64.0 ft) in length. 



Field Experience 



Operation: Litter entrapment was cited as a major problem. Anchoring system 

 and mooring -line failures were regarded as moderate problems. Much of 

 this trouble was solved by using rectangular-shaped blocks instead of 

 cylindrical weights. Coupling failure, structural failure, and instability 

 were all cited as moderate problems. Presumably, these all reflect the 

 quick failure of cable as a coupler and the steady failure of chain as its 

 replacement. Fouling growth and inadequate buoyancy were both considered 

 minor problems. Under typical storm conditions with waves 2.4 m (8.0 ft) 

 in height and 17.1 m (56.0 ft) in estimated length, the transmission 

 coefficient was 0.50. 



Maintenance: Scheduled maintenance consisted of regularly inspecting the 

 structure and realining it when necessary. 



Cost: For the reconstructed FTB, the coupling materials cost $5,228 while 

 the mooring system components cost $2,880. Navigational lights and 

 buoys cost $5,860. Total labor costs were $2,650. These figures 

 translate to an overall cost of $8.59/m 2 ($0.80/ft 2 ) in 1980 dollars. 



Benefits: The breakwater was seen as having a positive effect on attracting 



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