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Old 11-12-2018, 14:18   #1
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Safety Factor for Multi-Part Lashing

If you make a multipart lashing (low friction rings or similar for eyes), how do you calculate the appropriate safety factor? We know that the lashing is somewhat lower than the sum of the legs, due to friction and un-equal loading. If you started it with a knot that also weakens the lashing (weakest link!).



Is there a published rule of thumb? For some things you can just add a lot, but for standing rigging, for example, you really should have a number. I've been doing some pull-testing and I've done some calutations based on friction (they are quite close), but I'll be darned if I can find a reference.


I recall Starzinger did some testing, but I'm only finding the summary, not the detail. Too bad he took his site down. So much good information.
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Old 13-12-2018, 18:13   #2
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Re: Safety Factor for Multi-Part Lashing

Around here we just multiply the amount of legs by the breaking load of the line, knowing that we'll put a generous safety factor into it. It's the very definition of a rule of thumb. Dunno if anyone's published that, tho.
My inclination is to disregard friction as unimportant--dyneema is slippery enough to equalize.
No doubt the folks who put a lot of money and effort into research and testing are reluctant to provide their findings to the world, though they can be deduced easily enough by deconstructing one of their products. I've done that once or twice.
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