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Prusik Cord Diameter

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 russholland 21 Nov 2015
Hi,

I'm making up some prusiks and wondered what the general opinion to cord diameter was?

I'm aware the smaller the diameter the more wraps are required to get the required friction but does the weight of the climber also have direct correlation with this and does this impact on cord diameter choice, the number of wraps or both?
 Sharp 21 Nov 2015
In reply to russholland:

Do a search on here it's been discussed a lot. In summary it's mostly down to personal preference, 5 or 6mm is fine, I use 5mm. The difference between 5 and 6mm is pretty minimal imo, I've used both and it really doesn't matter. Weight wont affect it for use as an autoblock as it's not really supporting the weight of the climber, a larger diameter cord is probably easier to move along the rope if you're constantly weighting it in ascent as it wont bite in quite so much.
 JJL 21 Nov 2015
In reply to Sharp:

> Weight wont affect it for use as an autoblock as it's not really supporting the weight of the climber,

Not sure what you mean here.

Prussic cord absolutely does support the weight of the climber.
That said, 5mm is fine.
1
 olddirtydoggy 21 Nov 2015
In reply to russholland:

I use 6 and it's always worked for me, moves nicely on the rope. If it's your first time using prussiks, train and test them out.
 Sharp 21 Nov 2015
In reply to JJL:
I maybe wasn't clear, I understood autoblock to refer solely to a prusik when used as a fail-safe for abseiling - perhaps that's incorrect?

Either way if a prusik is used for abseiling then it replaces your hand in case you let go, the descender takes your weight even though the prusik or your hand still holds the rope. You wouldn't have a hope in hell of holding your entire weight with one hand wrapped around a pair of 8mm ropes, the force needed to hold the rope below the descender is minimal and that's all the prusik is doing, not holding the weight of the climber. If it did more people wouldn't clip it to their leg loop.

Of course you could tie it above the descender and then it would take all your weight but I've never met anyone who does that, the only time I can think you would would be if you were going to have to pass a knot but then that's probably quite a rare occurrence.
Post edited at 10:09
Andy Gamisou 21 Nov 2015
In reply to Sharp:

> I maybe wasn't clear, I understood autoblock to refer solely to a prusik when used as a fail-safe for abseiling - perhaps that's incorrect?

I sometimes use prusiks for prusiking in which case they definately take my weight

 deepsoup 21 Nov 2015
In reply to Sharp:
> I maybe wasn't clear, I understood autoblock to refer solely to a prusik when used as a fail-safe for abseiling - perhaps that's incorrect?

It is. A prusik loop used for progress capture when hauling/hoisting is also an autobloc. I don't think it's wrong to use that word to refer to a back-up on the dead rope whilst abseiling, but the progress capture thing is certainly what comes to my mind.
OP russholland 21 Nov 2015
In reply to russholland:

Thanks for responces just what I thought.
 climbwhenready 21 Nov 2015
In reply to russholland:

> I'm aware the smaller the diameter the more wraps are required to get the required friction

Other way round...

The diameter of the rope also matters.

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