Davis (1977) and Shaw and Ross (1977) conducted in-situ saltwater tests to 

 evaluate the reliability of 12 different potential materials for connectors. 

 The binding material recommended above all those tested is conveyor belt edg- 

 ing material (a scrap product resulting from the trimming of new conveyor 

 belts). This material demonstrated ultimate tensil strength on the order of 

 9,500 pounds per square inch, and is available from several manufacturers. 

 Minimum recommended belt dimensions are 2 inches wide by 0.375 inch thick, 

 with three or more nylon plies. This material can be easily cut with a band 

 or hacksaw, and holes can be punched singly or with a multiple punch. Con- 

 veyor belting is virtually inert in the marine environment. Shaw and Ross 

 (1977) recommended the use of nylon bolts, nuts, and washers as a means of 

 fastening the belting together. Heavy steel chain is recommended as a 

 secondary choice. Materials definitely not recommended for assembly of the 

 units include nylon lines (poor abrasion resistance, knot-loosening, and 

 ultraviolet degradation) and metallic-wire rope (inherent corrosive problems, 

 metal fatigue, and cutting action of the rope on the tire body). 



Shaw and Ross (1977) found that in addition to being inert in seawater, 

 conveyor belting has excellent abrasion resistance to chafing against tire 

 casings, and it showed no signs of delamination. The belting allowed loading 

 to be distributed throughout the entire system and was essentially unaffected 

 by ice conditions. The belting material is readily unfastened for addition of 

 tires or for other repairs. 



b. Foaming for Buoyancy. Air trapped in the tire crowns provides suffi- 

 cient buoyancy to keep a floating tire breakwater afloat for a while. How- 

 ever, to ensure that the structure remains in a position to provide protection 

 for up to the estimated 10-year life, supplemental flotation should be added 

 in every tire. Candle (1974) described a technique for onsite foaming of 

 scrap tires that can be easily handled by one or two people. This technique 

 uses simple, flat plate molds to hold expanding urethane foam inside the tire. 

 The foam is a two-component pourable mixture of a 1:1 ratio by weight which 

 can be easily mixed by an electric drill-type mixer. The liquid foam can then 

 be poured into the tires where it expands and cures in about 15 minutes. It 

 may be necessary to vent the top half of the tire if trapped air voids occur 

 under the sidewall areas. This is easily accomplished by drilling holes 

 through the upper part of the tire to allow air to escape as the foam rises. 

 Other types of flotation materials, such as milded polyethylene floats or 1/2- 

 gallon plastic bottles inserted into the tires, have also been used. Com- 

 pletely uniform flotation will facilitate interconnecting the units in water, 

 and the independent flotation of each unit allows the interconnecting hardware 

 to be used with maximum efficiency. 



c. Mooring Systems . The type of line or chain used to moor a floating 

 tire breakwater is important from the standpoint that it must be strong enough 

 and resilient enough to withstand peak forces and fatigue failures. Local 

 experience in mooring large ships has been used as a guide, and past studies 

 have indicated that the vertical load on the anchor should be minimized. The 

 mooring line should have a minimum length of approximately eight times the 

 maximum expected water depth and the anchor should be positioned seven times 

 the maximum water depth from the breakwater (Giles and Eckert, 1979). During 

 storm conditions, local seas have to lift the mooring line off the bottom 

 before forces are applied directly to drag the anchor; hence, many builders 

 have used chain (either galvanized steel or wrought iron) rather than other 



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