Abrasion and Break Testing

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abrasion tests

abrasion tests

Testers first task was to determine whether any of these coatings could weaken line in the near term. To do this, we formed 20-inch loops of 1/8-inch polyester braid and nylon braid, coated a 1-inch length of the loop with each of the products, and broke these in our test rig.

To test for chafe protection, we started with polyester double-braid line (3/8-inch diameter) rather than stitched eyes because this reduced the number of variables. We focused on polyester double braid because it is the most common line, and even high-modulus lines commonly have polyester covers.

Our test machine was a wood lathe that we modified to chafe lines at a realistic speed. The setup was efficient and allowed us to select an ideal load and abrading surface. The machine pulled a test line back and forth at a fixed rate (amplitude was -inch at 7 hertz) and velocity (1.4 feet per second). For this article, we settled on three pounds of line tension (applied by a spring scale) and a deflection angle at the abrading surface of 45 degrees.

Our abrading surfaces were wood (fresh sawn surface for each trial) and a medium-grit, aluminum-oxide grinding stone. For coatings, we ran each test until the rope cover failed. For physical protectors, we ran each test until the physical cover failed. The accompanying Value Guide describes these important differences in the way testing was conducted for each type of product.

To test a stitched eyes ability to resist abrasion, we ran the stitched portion on our machine for a fixed period (the time required to abrade roughly 30 percent of our test ropes cover when unprotected), and then tested for strength. We tested both eyes that had been stitched using round stitching and basting. We tested polyester and Dyneema twine.

For long-term testing, we constructed 8-inch-long samples of the various products and left them to weather. After a fixed period of exposure, the samples will be break-tested. Another set of control samples are being stored inside. These samples will be break-tested every two years, for six years. Unprotected line, webbing, and whipping twine have also been left outdoors.

On a test boat that is stored on the water year round on Chesapeake Bay, we have installed a wide variety of covered splices, sewn and conventional, with the various protective materials. We also coated certain lines where abrasion has been a minor problem but where fitting bulkier chafe gear would be impractical.

Darrell Nicholson, editor of Practical Sailor, grew up boating on Miami’s Biscayne Bay on everything from prams to Morgan ketches. Two years out of Emory University, after a brief stint as a sportswriter, he set out from Miami aboard a 60-year-old wooden William Atkin ketch named Tosca. For 10 years, he and writer-photographer Theresa Gibbons explored the Caribbean, crossed the Pacific, and cruised Southeast Asia aboard Tosca, working along the way as journalists and documenting their adventures for various travel and sailing publications, including Cruising World, Sail, Sailing, Cruising Helmsman, and Sailing World. Upon his return to land life, Darrell became the associate editor, then senior editor at Cruising World magazine, where he worked for five years. Before taking on the editor’s position at Practical Sailor, Darrell was the editor of Offshore magazine, a boating-lifestyle magazine serving the New England area. Darrell has won multiple awards from Boating Writer’s International, including the Monk Farnham award for editorial excellence. He holds a U.S. Coast Guard 100-ton Master license and has worked as a harbor pilot and skippered a variety of commercial charter boats.

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