Construction: This FTB is 137.2 m (450.0 ft) in length and 9.1 m (30.0 ft) in 

 width. The original structure relied on polyethylene blocks inserted in 

 the tire crowns for proper flotation. After reconstruction, the 

 breakwater relied on polyethylene scrap sealed in the tires by wire mesh 

 and polyurethane foam for adequate buoyancy. Rubber conveyor belting 

 fastened by nylon bolts was used to couple the tires. The operator noted 

 that punching holes in the conveyor belting and tightening the belts was 

 difficult. 



Site: 



LONG ISLAND 

 SOUND 



IN 



T 



Installation: The first structure was moored to fourteen 23 kg (50 lb) 



danforth anchors with ten anchors positioned on the exposed side and four 

 on the leeward side. Mooring lines were of nylon/chain and were 27.4 m 

 (90.0 ft) in length. The reconstructed FTB was moored by a system 

 including eight 91 kg (200 lb) danforth anchors, eight 227-kg (500 lb) 

 cement blocks, one 726-kg (1,600 lb) Navy stockless anchor, and one 908-kg 

 (2,000 lb) Navy stockless anchor. Each anchor was also fitted with 6.1 m 

 (20.0 ft) of one inch steel link chain, weighing 91 kg (200 lb). Mooring 

 lines were of 0.75-inch nylon and were 27.4 m (90.0 ft) long. 



Special Equipment: Two fiberglass light buoys were situated near the FTB to 

 warn boaters of its presence. 



Field Experience 



Operation: Anchoring system failure posed extreme problems to the survival of 

 the breakwater (see Severe Storm Effects'). Fouling growth was also 

 considered an extreme problem resulting in inadequate buoyancy as a major 

 problem. The flotation systems were relatively unsuccessful. The first 

 attempt, relying on inserted polyethylene logs, failed totally with the 

 logs coming loose and washing away under moderate wave action. The second 

 system fared better, though the brittle polyurethane foam would break 

 under severe wave action and allow the polyethylene scrap to escape. This 

 result was particularly noticeable on the outer tires. Litter entrapment 

 was viewed as a moderate problem. Structural failure, interference with 

 boating traffic, and coupling failure were all cited as minor problems. 

 Under typical storm conditions with waves 1.7 m (5.5 ft) in height and 

 31.9 m (104.5 ft) in estimated length, the transmission coefficient was 

 0.82. 



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