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Two Ropes of Unequal Diameter |
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10-Jun-2009 11:09:52 PM
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Is there any issue of tying the European death knot (Overhand knot?) with two unequal rope diameters? (ie 11mm and a 9.8mm). To be used as a single rop to extend an abseil on a multi pitch. I cant see any issue but I could be wrong - and I would prefer to be right before I try it
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11-Jun-2009 9:04:05 AM
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No
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11-Jun-2009 10:39:18 AM
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The DAV (sort of the german vcc) tested connecting ropes with different thickness in the lab and they (somewhat surprisingly) found that it actually works even better than if you use two equal diameter ropes. so no worries there.
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11-Jun-2009 11:10:44 AM
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I've rapped on an 8.8mm tied with a 9.7mm, I tightened the knots really well, strand by strand before jumping on and it worked well enough.
If it worries you, leave longer tails and/or use the extra tail to tie a second "back-up" EDK (I do both on some occasions if i'm feeling particularly whimpy)
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11-Jun-2009 12:24:59 PM
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it actually works even better than if you use two equal diameter ropes
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11-Jun-2009 1:22:16 PM
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On 11/06/2009 das_blob wrote:
>The DAV (sort of the german vcc)
Deutscher Alpenverein <--> Or literally the German Alpine Union... I'd suggest that calling them 'sort of the german vcc' is short-selling the DAV a little bit.
What with them having a bit over 3000 times more members (315,000 vs 265).
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11-Jun-2009 1:58:20 PM
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On 11/06/2009 hotgemini wrote:
>What with them having a bit over 3000 times more members (315,000 vs 265).
Your maths is off. 315000/265 ~= 1188.68
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11-Jun-2009 4:00:04 PM
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No, my maths was fine, my typing just sucked, should read 815000/265 ~= 3075.
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13-Jun-2009 10:46:59 AM
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The rope diameter differences will work in your favour...
...just make sure your belay device is smooth when using different ropes though.
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13-Jun-2009 12:58:16 PM
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On 11/06/2009 hotgemini wrote:
>
>Deutscher Alpenverein <--> Or literally the German Alpine Union... I'd
>suggest that calling them 'sort of the german vcc' is short-selling the DAV a little bit. What with them having a bit over 3000 times more members (315,000 vs 265).
It must be the schnitzels that they come for on club nights
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15-Jun-2009 10:55:55 AM
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just been using 9.4 with a 6mm tagline, works fine. a bit hairy tho!!
rock on
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15-Jun-2009 12:06:05 PM
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I regularly rap on a 10.5 and 8.5mm combo and have had no issues. The usual rules apply, dress the knot with at least 0.5m free ends and tighten it. I always weight the rap setup to fully tighten and check all is well (knot, threading, anchor, rap device cliped and threaded correctly) before I unclip myself from the anchor.
The thin rope will stretch up to a meter and can jamb the knot against the anchor or could saw through an abeil sling (in theory). But I haven't seen this happen. What's more likely to happen is that the thin rope can feed through the rap device more.
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