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I've got an 11mm static rope. Can I use it safely for top-rope belay/rappel with a belay device that is designed for "9.5 - 10.5 mm rope"?..

I actually rappelled three times with no issues but the rope felt very thick and stubborn. Can it be seriously damaged by the belay device or are those extra 0.5mm nothing to worry about?..

EDIT (after helpful comments) for someone finding this question later

DON'T use static rope for real climbing in the mountains! Even a short fall with a small amount of slack can generate astonishing force acting on your body (you won't fall down but you won't survive the shock!)

When I said I use this rope for top-roping, I meant some special situations (e.g. top-roping a tall tree for practice with no slack in the system - I don't want to have a dynamic fall with rope stretching and throwing me on some branch!)

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There are two factors to care about here: a static rope and a rope that is slightly too thick.

Static ropes are usually less flexible than dynamic rope, which would explain the stubborn feeling.

0.5mm of thickness is generally nothing to worry about. The main concerns with the manufacturer-approved ranges of rope thickness are safety and "user experience". When using a rope that is too thin for a given belay device, there is a possible safety risk because the device might provide less friction or not fully stop the rope (in the case of assisted belay devices). Too thick ropes generally only affect the "user experience" part: As you experienced, handling will become more difficult as the device will possibly provide much more grip than needed. Regarding the safety, I would not worry about such a small difference. For example, a 10.5mm rope might become slightly "fluffy" with age and, thus, even thicker than a new 11mm rope.

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  • 1
    good point about the risk with climbing. This is not only about becoming uncomfortable though: depending what kind of anchor you are toproping from it could also fail, since the load is much larger than with a dynamic rope. Nov 18 '20 at 17:34
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    The recommendation against climbing on a static rope should be much stronger. Taking a significant fall on a static rope can cause severe injury. It's basically no better than hitting the ground.
    – user2169
    Nov 18 '20 at 17:35
  • @BenCrowell absolutely. You may think the slack is small, but the rope is actually caught behind a stone, or the belayer gets distracted, and you've got a few meters of free fall.
    – IMil
    Nov 19 '20 at 0:00
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    Thank you everyone! I do have a dynamic rope and use it for climbing. Static rope is reserved for some special situations such as sport climbing in a gym with top-rope or rappelling down a tree after dismantling a rope bridge (built from this very static rope). Or top-roping up a tree (I don't want to have any slack in the system, would rather not fall and hit the branches :)
    – Alexander
    Nov 19 '20 at 9:08
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    I'm going to edit out the final paragraph of this answer. Since the OP has clarified that they have no intention of climbing on a static rope, the final paragraph is no longer needed, and it could also be dangerous to people who don't understand that it understates the danger.
    – user2169
    Nov 19 '20 at 14:35

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