TECHNICAL FORUMS > Equipment

Quoted rope strengths

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Fjell:
If you are looking in the 9-10mm diameter range, there is quite some variation in quoted strengths for a given weight per metre given it is all nylon. I accept there are different constructions, but still.

In the never-ending struggle between how much you can get in one bag on one hand and abject terror on the other, I have sort of decided I would like Type A rope, but not too heavy.

9.5mm Edelrid Super Safety is quoted at 59g/m for 2200kg. So about 37kg/g/m.
Gleistein 9mm is 54g/m for 2700kg. So 50kg/g/m.
Spelenium Gold 9.5mm is 33kg/g/m. I own quite a bit of this. The whole spec is exactly equal to the Type B spec, which seems a bit of a threshold thing to a suspicious engineer.

So some “interesting” things going on.

I am going to get some of the Edelrid. I trust them and it’s tested to Type A. That’s my selection criteria.

Ian Ball:
I go for the cheapest a caving shop sells.  trust in the shop, more rope for the cash.

Mike Hopley:
I think I would actually trust something like Beal Spelenium 8.5mm more than a basic 9mm or maybe even 9.5mm. The core-sheath bonding is relevant if the rope gets loaded over a bad rub point -- I have seen this happen on a real caving trip, and I believe the "fancy" rope made the difference between life and death.

Of course, that should never happen, but I think ropes are far more likely to fail from caver cock-up than because they have a slightly lower-rated breaking strength.

Oceanrower:
Since most gear is rated to 22kn and I doubt you weigh over 420 stone or will be vertically lifting two cars, isn't the point a tad academic?

Fjell:
I would think my 3-4 year old Spelenium is no more than 10kn when knotted now if you believe their quoted strength when new. Possibly less.
If you drop-tested a locked descender or Stop you would probably be getting there at FF1. Which does encourage you to space out single bolt rebelays.
I flatly refuse to go down any pitch where the rope is rubbing these days. Happy to go home. Being able to see the belay from below with your new very bright light helps too.

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