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Knot less rigging on a budget.


Mick Dempsey
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Please explain why metal on metal is bad

 

2 ways to look at this.

 

Firstly I downloaded the first five instructions for carabiners that I could find. Every one of them said don't use carabiner on carabiner. So if you do you are not following manufacturer's instructions and you're possibly not covered if it goes wrong.

 

Secondly, whilst a rope round a carabiner spreads its load on the metal over quite a wide area (conservative estimate for a 13mm rope would be about 160mm2), metal on metal is almost point loading, again conservative estimate 4mm2. That's increasing the load on the metal by 4000%. I can't prove it, but that seems a big risk to take.

 

Maybe there's a third point although it may be part of the first point. If you clip two crabs together, pressed against a length of timber, you are putting them both in torsion. They're not designed for anything other than very directional tension. Failure is not only possible but likely.

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