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rob

Tied vs. Sewn runners

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Hey, maybe this has been asked before but I couldn't find any similar posts.

 

My question is this: I've been told that sewn runners are stronger than tied runners. This makes sense. But how much stronger? Does this mean that tied runners are less safe? If tied runners are safe enough, then why do I need to extra strength of a sewn runner?

 

The other thing I am told is that tied runners can "jam" easier when used to make alpine 'draws. Is this really a big enough problem to spend the extra money on sewn runners?

 

I'd much rather just buy 30' feet of webbing and make my own runners as needed. Tied runners appeal to me because they are cheap, and I can re-tie them as needed. Also, with cheap webbing, I am more likely to replace it or leave it on a route (i.e. making a rap station.)

 

TIA!

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Tied runners are less strong because webbing (or ropes or whatever) are weakened by knots. I don't know about webbing, but the loss of strength of a rope by putting a knot in it is usually about 30%. If we assume that is approximately true for webbing as well, then webbing rated to 25kN would fail at 17.5kN in tied sling form; still plenty strong enough. For reference, a "typical" lead fall will only generate 4-6kN, though higher forces are obviously possible.

 

My main objection to tied slings is their bulkiness, the inconvenience of the knot getting hung up on stuff, the (slight) chance that they could come untied, and their weight.

 

The new generation of skinny slings (8-10mm) are very sleek and lightweight. Very nice. Once you've handled and used them, its hard to imagine going back to tied slings.

 

If you are short on cash or happy with tied slings, stick with them. They are not unsafe. Just periodically check your knots to make sure they aren't "creeping" (tails getting shorter) which could lead to them coming untied at an inopportune time.

 

I usually carry about 30' of 5-6mm cordelette for building anchors, slinging big boulders, etc. I'd use that stuff if I needed to bail off a route or rebuild a rap station. On infrequently traveled routes, I generally bring a bit more cheap webbing or cord that I wouldn't mind leaving behind.

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I used tied runners for a long time until I found the super-light weight 8mm Mammut sewn slings. It saves a good amount of weight compared to the bulkier tied slings and they work just as well. I still bring a few tied slings for leaving on rap anchors, trees, etc so that I don't have to leave one of the $10 suckers.

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The strength difference is pretty much irrelavant - people weren't dying in the old days from knots parting or coming undone. Also, they were usually carried over the shoulder as opposed to in alpine draws.

 

With regard to 8-10mm Dynemma slings - they should be considered a consumable commodity tossed and replaced every 2-3 years. I had several of mine tested at the two year mark and they pulled at 2/3's of their rated strength (around 14kn). Still stronger than most stoppers and cams, but you shouldn't think of them as having anywhere near the longevity of straight nylon slings...

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Tied runners are less strong because webbing (or ropes or whatever) are weakened by knots. I don't know about webbing, but the loss of strength of a rope by putting a knot in it is usually about 30%. If we assume that is approximately true for webbing as well, then webbing rated to 25kN would fail at 17.5kN in tied sling form; still plenty strong enough. For reference, a "typical" lead fall will only generate 4-6kN, though higher forces are obviously possible.

 

My main objection to tied slings is their bulkiness, the inconvenience of the knot getting hung up on stuff, the (slight) chance that they could come untied, and their weight.

 

The new generation of skinny slings (8-10mm) are very sleek and lightweight. Very nice. Once you've handled and used them, its hard to imagine going back to tied slings.

 

If you are short on cash or happy with tied slings, stick with them. They are not unsafe. Just periodically check your knots to make sure they aren't "creeping" (tails getting shorter) which could lead to them coming untied at an inopportune time.

 

I usually carry about 30' of 5-6mm cordelette for building anchors, slinging big boulders, etc. I'd use that stuff if I needed to bail off a route or rebuild a rap station. On infrequently traveled routes, I generally bring a bit more cheap webbing or cord that I wouldn't mind leaving behind.

 

I enjoyed reading this one, seriously. I started with tied slings, and have since gone the way of the skinny Mammuts.

 

Out of curiousity, what is the accepted amounts of tail for tied slings and cordalettes?

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Mine are tied an I have never had a problem. Most of the time I have about 6 2 foot slings (doubled over) and a few sport draws on my harness, and 2-4 4 footers over my shoulder. I have used other people's sewn runners and look forward to getting some myself when I have some extra cash, but for now my money is being spent on gas.

Check your knots before every day of climbing.

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Out of curiousity, what is the accepted amounts of tail for tied slings and cordalettes?

 

Mine have about 3" of tail. I have fallen on them and lived to tell the tail thumbs_up.gif.

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As far as the weight/bulk thing.....I think I read that the new skinny dyneema is something like 1/8 the weight equivalent strength nylon, and it's is much less bulky (in the pack and over the shoulder). If you are carrying 8 - 10 slings, this adds up (maybe a pound). Dyneema slings also makes nice manageable extendable draws. This gives you a lot more flexibility than carrying slings and draws. I carry a cordolette for anchors that can double for bail anchors.

 

You may spend $50 bucks more out of the gate, but it's worth it for the reduction in weight and bulk. Saving a pound in other areas (tent, stove, titanium pots, etc) will likely cost you more. I've seen guys wearing 8 nylon runners over the shoulder, and it didn't look comfy.

Edited by ericb

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I end up with a bit of a broad mixture. For trad cragging I tend to take alpine style draws instead of sport draws. They're nice floppiness makes me happy when I'm clipping nuts and cams smile.gif I prefer them mostly because they don't get hung up on stuff and if i'm pushing my own grade at all I want to be able to place and clip gear as efficiently as possible. Tied work fine, but I'd probably make up a seperates set of short tied draws (1 ft long?) instead of using standard single (3ft?) draws that have been trippled over. (trippled over, tied singles get messy and futzy frown.gif ).

 

For alpine stuff I end up with a mix. Sewn alpine draws for singles, 1 or 2 sewn skinny doubles and 2 to 4 tied doubles (the 9/16th's climb spec stuff, not the 1" nylon). That way I've got a handful of runners that I don't really care about keeping nice (good for slinging chock stones, sap covered trees, building rap stations etc).

 

so... yes, definitely worth having, and seriously cut down on bulk for the draws. I don't think I'd make single length alpine draws with 1" tied webbing, at that point they're better over your shoulder.

 

as has been noted... strength doesn't really come into the question, it's more about bulk, futzing, and efficiency.

 

wave.gif

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Mountaineers book states that you lose 20-30% reduction in breaking strength when tieing runenrs with a water knot. Also states the tails of a tied runner should be minimum 2-3 inches long, and as mentioned above the knot should be checked often to make sure it hasn't worked itself loose. For a note of persoanl preference I like having both sewn and tied runners available, they both have different advantages. However, someone needs to make a device that allows you to tie two runners the exact same length.

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However, someone needs to make a device that allows you to tie two runners the exact same length.
Tell us why it this is important.

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Mountaineers book states that you lose 20-30% reduction in breaking strength when tieing runenrs with a water knot. Also states the tails of a tied runner should be minimum 2-3 inches long

 

Some rules of thumb:

 

A good tail length is the width of your palm. Except the EDK.

 

Any knot reduces MBS by 1/3.

 

These are easier to remember, as there's no need to memorize exact numbers.

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I'd prefer it, so that when I use two slings, one as a backup, off the same anchor, like say a tree being used for rapelling. I prefer that the runners are the same length. If there not he same length then I find that one runner is supporting all the weight, while the backup is just dangling there waiting for the first runner to break before being weighted. Thats just a scenerio I have found. Basically anytime I use two slings off the same anchor I find it nice that they are even lengths. Thats my reasoning behind it and I'm sticking to it. LOL. However, I never said it was important smile.gif.

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All great points! IMHO, figure what works best for you. If budget (or beliefs) don't allow for fancy sewn runners, use tied. I always keep a few tied runners fot replacing the mank at the rap station. Always seems to be a pain in the ass to put place a sewn runner into the rap station.

 

That said, I used to use prusiks to jug 'cause I was too poor (cheap) to buy ascendars. Why not climb with all hex's and nuts, saving your cam money for more beer? Heck, I even used to climb with a 1" webbing harness in the early days, cause I couldn't afford a real harness.

Of course, half the fun is having the coolest gear out there, something for us to obsess over, right?

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one argument in favor of tied runners that I rarely hear anymore is the shock-absorber effect as a knot tightens under a shock-load. A study conducted by a consortium of European rope manufacturers, presented at the 1987 spring meeting of the California section of the AMGA concluded that, on average, about 30% of the impact force of test falls was aborbed by the tightening of knots in the belay system. I infer from this that a tied runner ought to transmit significantly less of the impact force of a fall to your placement than a sewn runner.

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Yeah, montypiton, use terms we can all understand. Who can possibly deduce the common meaning of shock-load as it relates to climbing? rolleyes.gif

 

 

For some definition fun, as per a google definition search,

Definitions of shock load on the Web:

 

* The arrival at a water treatment plant of raw water containing unusual amounts of algae, colloidal mater, color, suspended solids, turbidity, ore other pollutants. [typically found soon after a resident shock loads his toilet moon.gif] www.nsc.org/ehc/glossar2.htm

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one argument in favor of tied runners that I rarely hear anymore is the shock-absorber effect as a knot tightens under a shock-load. A study conducted by a consortium of European rope manufacturers, presented at the 1987 spring meeting of the California section of the AMGA concluded that, on average, about 30% of the impact force of test falls was aborbed by the tightening of knots in the belay system. I infer from this that a tied runner ought to transmit significantly less of the impact force of a fall to your placement than a sewn runner.
I would be willing to bet that if you went to the trouble to set up a test system, you wouldn't be able to measure any significant difference in impact force.

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shock-load

 

Please define this ridiculous term. Bonus points if you can find it in a physics or engineering textbook.

Shock-load is a term that doesn't really add any additional meaning to the word "load". It just refers to a large load resulting from the lack of energy-absorbing elasticity in the system.

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