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that high-tech fibers really earntheir keep. Take for examplesimilar diameter lines that areeach 100 feet long and loadedto 30 percent of their brakingstrength. The higher end PBO,Vectran and Dyneema (Spectra)products will stretch lessthan a foot under such loadwhile conventional lowerpricedpolyester products willadd three feet to their length.Combine this data with thefact that 30 percent of thebreaking strength of a top-endline is about triple the strengthof a lower-cost Dacron product,and you can see thatstretch minimization per equalload is even more impressive.The bottom line is thatstronger, less stretchy, lighterlines are like better quality tools— likely to be worth theinvestment in the long run.Tensile strength and elongationare by no means the onlyconsideration when it comes tocordage consideration. Creep(elongation under load), UVstability, abrasion resistancehandleability and cost are alsokey factors. For example, whenit comes to replacing a wirehalyard with rope, stretch isonly one factor. Other variablesthat need to beadded to the mixare issues such asthe manufacturer’sline diameterto sheave radiusratio, or how hardthe cordage canbend withoutharming the fiberbundles. There’salso some concernabout the cover materialand special coatings on the linethat help keep UV and chemicaldamage, caused by atmosphericdeposition (acid rain,etc.), at a minimum. In short,A light, strong nonwaterabsorbentDyneema core/polypropylene covermakes for an ideallight air sheet.Offshore Swan Sailing ProgramMay:June:St. Maarten to NewportBermuda Cruising Rally with Tania Aebi SailNY to Bermuda or backFrom only $1400Offshore Passage Opportunities# 1 Crew Networking Service since 1993.Sail for free on OPB’sCall 1-800-4-PASSAGEfor free brochure/membership application.Need Crew?Simply contact us!www.sailopo.comCREWwww.oceannavigator.comSEPTEMBER 2010 OCEAN NAVIGATOR 43