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Dodgy toprope anchor testing

mikllaw

14-Oct-2015
9:32:30 PM

To the lucky people who made this toprope anchor with (new) Bunnings cord and a new screwgate, I have your anchor and 4 mats that were blowing around the crag. Contact me and I'll give you some free climbing rope.

note unique 3 into 2 overhand

Out of interest I tested the cord over fat biners in 2 configurations, clove hitched and with an f8 in each end. the failure loads were 2.4 and 2.7 kN respectively. Could you have been toproping on the bunning cord? I think it could have failed in a toprope fall. Maybe that's why you left in a hurry.

(The core is also polyester, but like a cigarette filter, and could be torn by hand)

ambyeok

15-Oct-2015
3:18:38 PM

Don't be such a nanny state nancy mikl. Bunnnings chord may not be very strong but its super light which makes carrying it to the crag a breeze. Plus its cheap so you can just leave it behind rather carrying it out. The only thing I can't really explain is the use of a rated biner, I assume that was just a happy accident.

Dr Nick

15-Oct-2015
8:03:17 PM

Exactly, you can get snaplinks at Bunnings just near the rope. And proper hexagonal nuts, not those weird curvy things. If you're worried about breaking gear, just put an occy strap on it as a load limiter.

mikllaw

16-Oct-2015
9:05:03 AM

I thought that the core might tear first, giving a jig in the load - displacement curve, but it was fused into the sheath.

Figure 8 curve, the rope snapped inside the F8

the rope snapped in the un-knotted section, not supposed to happen unless you have variable strength.

grangrump

16-Oct-2015
9:20:09 AM

2 to 3 kN
so would nearly break with just the weight of climber and belayer alone, let alone any fall...
ouch

IdratherbeclimbingM9

16-Oct-2015
9:34:59 AM

On 16/10/2015 grangrump wrote:
>2 to 3 kN
>so would nearly break with just the weight of climber and belayer alone, let alone any fall...
>ouch

Yes, and I noted that too in the original post by mikl.
This is also not unlike the strength rating of the smallest RP's, and other small protection that their manufacturers rate for bodyweight only usage...

A question for mikl;
>the rope snapped in the un-knotted section, not supposed to happen unless you have variable strength.
I note the stopper knot on the clove hitch, which presumably prevents 'rope' slippage, so would the failure mode be different without that if it was fully rated climbing rope instead of Bunnings rubbish?

mikllaw

16-Oct-2015
10:01:09 AM

On 16/10/2015 IdratherbeclimbingM9 wrote:

>A question for mikl;
>>the rope snapped in the un-knotted section, not supposed to happen unless
>you have variable strength.
>I note the stopper knot on the clove hitch, which presumably prevents
>'rope' slippage, so would the failure mode be different without that if
>it was fully rated climbing rope instead of Bunnings rubbish?

The polyester was very slippery so I put it in to limit slip. Nonetheless I expected the rope to break at a knot, the only way the rope can break in the straight section is if the rope locally is weaker. Clove hitches are about 60% strength, so the rope at 1 point was 60% of the average strength. You wouldn't expect this strength variation with a well-made climbing rope.

lacto

16-Oct-2015
11:20:15 AM

I have had 2 experiences with a 30 m Buunings rope
1 A heifer (500 Kg ) somehow ended up in my Manure dam ( where she was stuck in the heavily soupy mess , the surface wasn't strong enough to support my weight to get to her and put a chain around her neck , only thing nearby was this Bunnings rope , lassoed her around the neck with a slip knot , hitched to the tractor and took off slowly rope stretched heaps, and started pulling her towards the edge of the shit when the rope snapped in the middle not on any of the knots , fortunately the noose loosened enough to stop her choking and pulled close enough to edge to get the chain on her , got her out but it took 5 days of watering and feeding before she stood up and walked away . So Bunnings rope helped save a $2000 heifer , that has since calved and had a heifer calf worth $500 .
2 Had a crazy cow which put in a stock trailer with a sheet of steel mesh over the top to stop her jumping out . Mesh was tied down by the remnants of the above rope and held until deliver to the abattoirs 50 kms away , the cow fought the whole way and the mesh was bent in many places but the rope held .
Since bought a length of good rope for these sort of situations

gfdonc

16-Oct-2015
1:15:53 PM

Please send your retired climbing ropes to lacto. He needs them more than you do.

kieranl

16-Oct-2015
1:48:47 PM

Maybe lacto could send Mikl a sample of cow-poo impregnated rope for testing.

lacto

16-Oct-2015
4:04:27 PM

have old ropes but no good as by the time you get the rope taut enough to pull too long a time and you'll end up strangling the animal and dodgey trying to back the tractor backup a steep dam bank . At least the chain can be fixed so won't strangle the animal they don't appreciate being pulled by the neck but better than dying in filthy water with a shitty crust . It was at the end of a really bad week where I tried to amputate 2 fingers and had pins in the fingers that were in a plastic cast and arm in a sling plus found at dusk and in drizzling rain

E. Wells

16-Oct-2015
4:08:59 PM

I found 60mtrs of this stuff tied in hard to an anchor in a popular canyon with bunnings snaplinks on end submerged in water attached to milky 7mm hardware braided rope prussic. I carried it out then used it once in another canyon but it was obviously hardware rope. I guess I threw it in the bin. The core looked like tissue paper!

martym

17-Oct-2015
9:27:13 AM

Out of curiosity, do you wear waders into the manure dam?

capt_planit

18-Oct-2015
10:44:09 AM

Excellent discussion arising from interesting pull-testing of hardware store rope. Prize cow in lagoon also very interesting; esp. since I didn't have to participate in said rescue. I wonder if the braided yellow poly stuff holds up a bit better?

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