Rigging with slings

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Re: Knot Break Strength vs Rope Break Strength

Postby knudeNoggin » Jun 30, 2006 10:20 pm

Tim White wrote:Take a look at the recent study titled Knot Break Strength vs Rope Break Strength, ...

NB: The two bar graphs of breaking strengths for the "half sizes"
--i.e., 12.5 & 10.5--are mistaken, each contains the other's data!

(The data tables are obviously correct, given the absolute values.)
:doh:

EDIT: ALL of the bar graphs confuse the 12.5/10.5mm ropes' data.
The 7mm data & the point-plot/connected-dots graph is correct.
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Postby hunter » Jul 6, 2006 11:23 am

Hey All,
Perhaps it does not apply to everyone but I think the weight and time saved by sewn slings can be substantial and the extra strength is always reassuring. I generally carry 30ft of webbing as well but in caves with a large number of drops and known rigging I think sewn slings make sense (assuming you can afford them which is an issue).

A bit of the original topic but on the backup of an 8, when I started climbing at a climbing gym backup was not required. About 5 years later they started requiring backup as required by the insurance company. I think the point here and the point no one has mentioned is that it is possible (however stupid) for someone to tie a figure 8 wrong. In this scenario a backup can save someone's life.

When I show people anchors (caving or climbing) or how to tie in I generally tie a backup for the above reason and because it forces me to have a decent length tail (and keeps the tail neat).

Perhaps it is not so much of an issue in caving but I tie the 8 ten or more times a day when climbing. Conditions in the mountains can be windy, icy and time pressure can be extreme (not to mention altitude issues), to me adding a backup is just one more little safety that might help in one out of ten thousand times.

James
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Postby NZcaver » Jul 6, 2006 1:32 pm

hunter wrote:...About 5 years later they started requiring backup as required by the insurance company. I think the point here and the point no one has mentioned is that it is possible (however stupid) for someone to tie a figure 8 wrong. In this scenario a backup can save someone's life...

I'm sorry - if someone ties a figure 8 so poorly that can slip apart, what makes you think their backup knot will be tied properly? :hairpull: It may *look* safer, but if not tied, dressed, and pre-tensioned properly it's really a waste of time and rope...
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Postby hunter » Jul 6, 2006 2:19 pm

NZCaver,
No gurantee at all, just probability. The odds of tying two knots incorrectly at the same time are lower than the odds of tying one knot incorrectly.
I believe the most experienced people (including myself) can make mistakes tying knots so I guess I don't see any reason to avoid using a backup for one particular knot. Telling beginners to always use a backup is also much simpler than having them try to remember which knots are ok to not backup,

James
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Postby Tubo Longo » Jul 6, 2006 2:28 pm

NZcaver wrote:
hunter wrote:...About 5 years later they started requiring backup as required by the insurance company. I think the point here and the point no one has mentioned is that it is possible (however stupid) for someone to tie a figure 8 wrong. In this scenario a backup can save someone's life...

I'm sorry - if someone ties a figure 8 so poorly that can slip apart, what makes you think their backup knot will be tied properly? :hairpull: It may *look* safer, but if not tied, dressed, and pre-tensioned properly it's really a waste of time and rope...

:exactly: I totally agree, and not only for a figure 8 knot, of course. If someone doesn't know how to properly set knots, on either rope and webbing, better him/her off the cave to learn knots than not in cave experimenting with their lives and the ones of their buddies. No back up will ever hold, it will just let people (wrongly) believe of being safer.

About sewn sling. hunter, I do believe they might be useful in many situations. But also there are at least as many situations, in my own experience, where you will be way better off with a sling you have to tie a knot in. A mix is the best way to go. my cent :-)
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Postby dcfdrescue2 » Jul 6, 2006 6:47 pm

Having taught several rope classes, one mistake I have seen a few times has been people inadvertantly attaching a carabiner to the little loop that is formed between the safety and the bottom of the knot. We do not teach this, but several people that have come through the class have been taught that by a local training facility.

A lot of these folks were beginners on rope, but it opened my eyes to the possibility of that happening.
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Postby hank moon » Jul 6, 2006 7:29 pm

dcfdrescue2 wrote:Having taught several rope classes, one mistake I have seen a few times has been people inadvertantly attaching a carabiner to the little loop that is formed between the safety and the bottom of the knot.


A properly tied safety will not have this loop...

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Postby NZcaver » Jul 6, 2006 7:44 pm

hank moon wrote:A properly tied safety will not have this loop...

Ah, but a properly tied figure-8 doesn't need a safety in the first place... :wink:

(Sorry - I couldn't resist continuing the chain of circular logic.) :tonguecheek:
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Re: Rigging with slings

Postby emileemanitou » Dec 3, 2012 4:24 pm

That knot link posted by chac doesn't seem to be live anymore. These knot videos are somewhat helpful however: http://www.manitouboats.com/blog/knots-yeah-more-knots-with-video/
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