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Brion Toss

Member Since 26 May 2007
Offline Last Active Today, 01:30 AM
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Posts I've Made

In Topic: Rope/knot/splice load testing

07 April 2014 - 10:30 PM

This is starting to remind me of an old Tom Robbins riddle: "If one and a half chickens lays one and a half eggs in one and a half days, how long would it take a wooden-legged monkey to kick all the seeds out of a dill pickle?"

But actually, I see now that the load on the eyes would remain approximately the same. That leaves the huge radius prescribed for the standing part, and there the load would in fact be doubled, yes? If that is so, it explains the extra-generous required radius.


In Topic: Rope/knot/splice load testing

07 April 2014 - 08:32 PM

Okay, but then when the sling is in a straight pull, the eyes would each have twice the load that they do when it's a basket. So why don't the eyes then need the same "huge bend radius"?


In Topic: Rope/knot/splice load testing

07 April 2014 - 07:20 PM

Yes, we are talking about a basket hitch (U-turn) configuration. But when the load is on that U-turn, the eyes take half the load each, yes? If so, there'd be less load on each eye than when the sling was in a straight pull configuration with the same load. This is without considering any angle to the hook.

Every sling I own is tagged showing that the basket configuration is rated at twice the strength of the straight pull configuration, so the manufacturer is counting on no loss of strength in the standing part. Except that, as I understand it, a larger D/d ratio is specified for the basket configuration than for the eyes, and I don't know why.


In Topic: Rope/knot/splice load testing

07 April 2014 - 05:40 PM

Yes, got that, but as I understand it, the D/d is different for a sling body than for the eyes in that same sling. And the reason is...?


In Topic: Rope/knot/splice load testing

07 April 2014 - 04:13 PM

Wow, things hotting up here a bit. I have a couple of Dux pieces made up, to ship out today (Monday). I'll also be seeing NER staff at the Oakland show in a few days. Meanwhile:

The break strength John posted (24,000lbs) is approximately what Hampidjan lists as a minimum break strength, but this appears to be deeply conservative, as actual breaks of 26,000 or so seem typical for that diameter. This might explain at least some of the apparent lack of strength loss from UV. A test of my new rope might confirm this.

Note that the eye-breaks in John's tests happened right up at the maximum likely strength of the rope; no significant weakening could have taken place.

With NER's help, I hope to have time, soon, to send off a few more samples, inlcuding 1:1 eyes, and splices whose tails approach closely.

As possibly the only non-engineer here, I'd love to see a simple-enough-for-sailors explanation of D/d ratios for sling bodies vs. eyes.