Before the tires are tied together to form a module, two 5.1- 

 centimeter- diameter (2 inches) holes are punched in the bottom and 

 flotation is added to the crown of each tire (Fig. 1) . The holes reduce 

 the amount of sand and debris which would accumulate in the tire, and 

 allow water to drain from the tires if the breakwater has to be removed 

 from the water. 



When placed vertically in the water, a tire traps a sufficient amount 

 of air in the crown to support its immersed weight. However, this trapped 

 air will dissolve with time or escape through holes in the tire. In addi- 

 tion, each tire provides an ideal environment for aquatic growth. The 

 additional weight of this growth plus the loss of trapped air will even- 

 tually cause some tires to sink. The use of flotation materials such as 

 rigid urethane or polystyrene will keep the breakwater uniformly afloat 

 and will permit the use of severely damaged tires which otherwise could 

 not be used. 



Individual 18-tire modules are constructed by stacking the tires in 

 a 3-2-3-2-3-2-3 combination and threading a line (e.g., chain, rope) 

 through the tires as they are stacked (Figs. 2 and 3). The weight of 

 the tire stack and physical con^ression of the tires by hand allow 

 fastening of the line to form a tightly secured unit. 



Various types and sizes of chain, synthetic rope, steel cable, and 

 plastic straps are being evaluated in field tests by the University of 

 Rhode Island, Kingston, Rhode Island, for use as a tieline (Davis, 1977). 

 Candle and Fischer (19 77) indicate that a specially manufactured 1.27- 

 centimeter (0.5 inch) unwelded, open-link chain is best suited for the 

 construction of floating tire breakwaters. The open-link chain has 

 adequate strength, is easily handled, and can be spliced with simple 

 handtools . 



2. Breakwater Assembly and Anchoring . 



Interconnection of the individual modular sections to form the desired 

 length and width of the breakwater is accomplished by rotating the four 

 corner tires of each module approximately 100°. Tires are then added to 

 provide interlocking with adjacent modules (Fig. 4). 



The breakwater is floated into position and moored (fore and aft) 

 using an open- link chain and steel cable normally placed on a 1 on 7 

 slope to the anchor. Mooring lines are attached to two modules every 

 15 to 30 meters (50 to 100 feet) (Fig. 5), depending on the mooring 

 loads expected and type of anchors used. The type of anchor depends on 

 bottom conditions and expected loads. Anchors which have typically been 

 used include formed concrete blocks, pilings, screw anchors, and embed- 

 ment anchors. 



3. Breakwater Costs . 



Total breakwater cost will depend on the labor costs for obtaining the 

 tires and assembling the tires into modules, and on types of flotation 



II 



