Swage Fitting Breaks Surprise PS Testers


During the first round of mechanical terminal testing, testers were surprised to see that wire failures were occurring at loads that were at least 10-percent lower than expected. The swaged-end fittings had been applied by a rotary swage machine, which is considered to be a very reliable way to form swaged terminals.

Only after our lead tester, professional rigger Brion Toss, took calipers to the failed swaged ends did he realize what was causing the failures. The shop hired to do the swaging was using a rotary swage machine that was out of spec. Whenever ordering swaged rigging, be sure to double-check that the swage machine to be used is within spec (regardless of machine type), and confirm that the finished swages are within the specified diameter. Ronstan offers a table on swage standards on its website.

Most rigging has a high safety factor that will tolerate a 10 percent loss in strength, but combined with other factors, substandard swages can lead to rig failure.

Marine Supply

1. We broke all samples at Oberts Marine Supply industrial yard in south Seattle.

2. The wire attached to the strongest terminal in our test broke at 22,000 pounds. It was a clean break, with the failure occurring several wraps from the nearest terminal.

3. Several of the out-of-spec swages failed inside or just outside the terminal, indicating that the terminal had weakened the wire. The only wires that pulled completely out of the terminals were the ones with sealant put on the ends before swaging.

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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