UKC

Im only just starting out in outdoor climbing so wont be doing anything major yet.
I was thinking of getting some rope to make a short and regular length prusik loop from, something like 5mm static.

At the moment the rope Ive got is a 10mm Edelrid dynamic and I was wondering if the 5mm would be suitable to use if I needed to abseil off my rope doubled up through a belay plate using a french prusik around both ropes, or would I need something wider diameter for this?

Sorry for such a long question!

In reply to owena:

5mm tends to grip a bit too fiercely. And 6mm not quite enough on single 9mm ropes. You can get 5.5mm sometimes. Grab it if you see it! If forced to choose, I would go for 6mm - it lasts a bit longer before it goes stiff and slippery.

In reply to owena: 5mm is fine 6mm is stronger for abbing off if needed but you have to usually add more turns to get the same grip you did with 5mm. maybe get a couple - one 5mm and one 6mm. just make sure they are plenty long enough. a length of cord about 1m should be enough.

In reply to Andy Nisbet: thanks for the input - would it make a difference what size if I was using it around two 10mm ropes side by side though?

In reply to owena: yes it will make a difference - the 5mm will be much more grippy than the 6mm for the same amount of turns of the prussic.

In reply to owena:

For me, if my life is hanging on a prussik it's got to be 6mm or more.

In reply to owena:

Yes, as someone else says. But I've not abbed much on double 10mm so I won't guess. But this topic is very valid. The cord, how thick, how stiff, how many turns, makes a huge difference to how well the system works and it's well worth getting it right.

In reply to owena: im not planning on doing it, but if needs must Id rather do it right

In reply to owena:

Diameter aside, softer cord bites much better than stiff chord.

In reply to owena: Prussics weigh very little and having a couple of differing diameter isn't going to stop you onsighting your next climb! as long as they are long enough, they will hold!

In reply to owena: With regards to strength, mammut Prussik cord is 5.5kn and 7.5kn for 5 & 6mm respectively.

For backing up an ab, or prussiking up a rope strength isn't an issue.

I carry one of each.

More importantly, practice using them before you're stuck at the bottom of a crag!

Thanks everybody Ive got my answers now - Im going to get a short and a regular in both 5 and 6mm just to be sure

5mm or 6mm it doesn't really matter which but useful advice is tie them ~long as a normal slim (60cm) - a bit over long for prusiking (but you can tie it off with and over hand knot to shorten it) but has many advantages such as it will be possible to wear it over your shoulder or use it as an extender. These a both very handy in the real-world "need to climb a rope" situations. That said I usually carry shorter ones if it isn't alpine stuff. TBH prusik loops are cheap and the sort of thing that come and go so don't panic it it isn't right.