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#25267 - 11/01/06 05:11 PM Re: Harness Safety [Re: GOclimb]
chip Offline
Carpal Tunnel

Registered: 10/06/01
Posts: 2677
Loc: Sittin' Pretty in Fat City
Nothing like a white hot ATC/GriGri up against the belly to wake you up.

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#25268 - 11/01/06 05:23 PM Re: Harness Safety [Re: GOclimb]
socialist1 Offline
member

Registered: 08/05/04
Posts: 147
Loc: New Brunswick, NJ
Hey all, check this out:

Belay loop strength

I found it to be worthwhile.

Ross

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#25269 - 11/01/06 05:43 PM Re: Harness Safety [Re: GOclimb]
ShakesALot Offline
enthusiast

Registered: 04/19/04
Posts: 257
Loc: NJ
Quote:

Quote:

With regard to the heat issue, according to eyewitness accounts, the rap device used was a gri-gri. I've never really rapped a long route with a gri-gri, so I wonder does it dissipate heat better or worse than an ATC. My intuition says better (more metal+larger area of contact with the rope), but that opinion is lacking any scientific data.

TS




In my experience rapping on a gri-gri, it gets extraordinarily hot. More so than an ATC, at least on fat ropes.

GO




fwiw - Petzl recommends not doing grigri rap's longer than 50m citing a risk of the device overheating as the reason.

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#25270 - 11/01/06 07:04 PM Re: Harness Safety [Re: socialist1]
irisharehere Offline
Site Supporter

Registered: 12/06/01
Posts: 1658
Loc: Danbury CT
Fish (Russ Walling) has also been doing some pull tests of lightly/partially worn gear that people have sent him, including harnesses, Mammut skinny slings, Spectra cord etc etc

It's being discussed on Supertopo, here

Supertopo discussion

Sound effects on the video are cool!

Irish
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#25271 - 11/01/06 07:50 PM Re: Harness Safety [Re: Timbo]
Julie Offline
Pooh-Bah

Registered: 01/16/00
Posts: 2090
Loc: SoCal
according to eyewitness accounts, the rap device used was a gri-gri

... also, he was rapping on a static line.

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#25272 - 11/01/06 09:49 PM Re: Harness Safety [Re: Julie]
Mike Rawdon Offline

Carpal Tunnel

Registered: 11/29/99
Posts: 4276
Loc: Poughkeepsie
Quote:

according to eyewitness accounts, the rap device used was a gri-gri





In my experience, THE CAM on the Grigri gets hot. But it doesn't efficiently transfer that heat elsewhere. The Grigri body stays cool, and I've never noticed any heating whatsoever of the biner. IMO it's this lack of heat dissipation that is behind Petzl's warning.

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#25273 - 11/01/06 10:46 PM Re: Harness Safety [Re: irisharehere]
MarcC Offline
Carpal Tunnel

Registered: 07/10/00
Posts: 3532
That's a great discussion on st.com that the irish rabbit posted. What I found particularly interesting, esp. in view of the comments here about using a prussik backup clipped to the leg loops, was Walling's findings when pull testing a harness:

As for the leg loop as a backup for your prussik or whatever while rappeling..... If you just clip your prussik onto the top of the leg loop (like I have seen many people do) the numbers ain't that good. Stitches started to blow at 340lbs and there was a total failure where you are out of the system completely at 800lbs. Survey says, at least use the main leg loop clip in point if you are going to use this method.
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#25274 - 11/02/06 07:06 PM Re: Harness Safety [Re: MarcC]
Julie Offline
Pooh-Bah

Registered: 01/16/00
Posts: 2090
Loc: SoCal
For several reasons, I am unconvinced by the tests linked above on backup devices. First, those were done on backups above the device only, so it's unclear at best whether the results apply to backups below the device. Second, it's unclear whether the subjects were experienced or naive users of rap backups, or even experienced rappelers (cavers rappel, but not nearly as often as climbers) - and people who are inexperienced with belaying or rapping *do* death-grip the rope above the device, while experienced folk leave it alone. Third, one of the dangers they cite is that a backup below the device might get jammed open by the device - which is easily prevented by length adjustments, and a red herring of an argument (of course it will fail if you set it up to fail).

I still think that a backup might have saved Skinner (though if he was going to back anything up, it should have been the belay loop first).

Because of Fish's tests (though they depend on how your leg loops themselves are constructed), I think I'm going to move towards rapping on an extended device, with a backup below and clipped to the main leg loop tie-in point.

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#25275 - 11/02/06 08:47 PM Re: Harness Safety [Re: Julie]
Dillbag Offline
old hand

Registered: 05/02/06
Posts: 1130
Loc: "The Town"
Quote:

with a backup below and clipped to the main leg loop tie-in point.




if you are really that worried about your belay loop breaking and need the extra back-up... it was stated previously that: "backing up off of the leg loop tie-in, the leg loops (if belay loop fails) will just slip off"
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#25276 - 11/02/06 09:05 PM Re: Harness Safety [Re: Julie]
pitfall Offline
old hand

Registered: 11/01/00
Posts: 1165
Loc: Albany
Quote:

(cavers rappel, but not nearly as often as climbers)



Walk off.
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