UKC

I'm sure this has been discussed before. B

What are people's views on using cordlette for extenders?

If so what diameter would be considered most suitable?

Does a double-fishermens weaken it?

Perhaps a more technical question...Would a 6mm, 60cm extended length of cordlette be able to withstand repeated fall factors of about 1.0 (not that I'm expecting to do this regularly!)?

You're probably going to ask why I don't just use sling. Nylon slings I find too big and bulky, and dyneema I find I'm having to replace quite often either from bailing, losing, getting frayed.

In reply to jungle:
Breaking strenght of 6mm Mammut prusic cord (when new) = 7.5 kN
Mammut 8mm contact dyneema sling breaking strenght = 22 kN.

BD X4 cam size .3 = rated at 6kN
DMM walnut size 2 = rated at 9kN

Force generated in leader falls often estimated at 5 kN if you have a big whipper.

6mm cordelette would be the weakest point when used in combinations with relatively small protection like a size 2 nut. Also, there is little margin for aging or wear, since it is only 2.5 kN stronger than a minimum "safe strenght" of 5 kN. This is even before we start considering the double fishermans knot.

I would stick to the dyneema if I were you.

In reply to timmeehhhh:
the loop with a double fishermans knot makes it stronger than a single strand

http://www.beal-planet.com/img/cms/sport/Tableau/cordonette-2EN.jpg

that said 6mm is a bit on the thin side. I think 7mm would be better and 8 if you want to be as strong as a sling

there are other options like this http://www.needlesports.com/50233/products/edelrid-12mm-tech-web-tape-oasis...

but its more expensive than dyneema slings

In reply to jungle:

I've used cord before when I was short on draws for some sport climbing, it was fine with some minor falls. Having looked at the numbers and being confident in tying a knot and regularly inspecting, I was happy with that for a few days. Can't remember the cord diameter, but it certainly wasn't less than 6 mm. In hindsight I'd guess it was 7 or 8 mm. I wouldn't do it longer term though as it's just one extra potentially weak link in the chain...

In reply to CurlyStevo:




Interesting table, thanks.

Reading that a good condition 6mm cord sling would give around 12Kn, well happy with that myself if the potential falls are low fall factor.

Interesting note on the 5.5 dynema.
Is quadruple fishermans in French, a double or quadruple fishermans this side of the Manche? Jon or Doug ????
Thought triple knots recommended in Dynema?

In reply to Rick Graham:
no worries

re the 6mm, you also have to consider it weakening with age and getting cut through more easily than 7mm.

5.5 dyneema is a well tightened (body weight) triple fishermans. Its not that cheap either though about 4 quid a meter and you can get this for 5.99 which is cheaper http://www.needlesports.com/251/products/dmm-11mm-dyneema-slings.aspx .

Imo the OP should just take a bit of cheap ab tat on climbs he / she may need to (prussic can often suffice I've found or take some proper tat on multipitch if there is a real risk of retreat). maybe get some hard wearing slings for the sling draws maybe something like this (http://www.joe-brown.com/9397/products/dmm-16mm-x-120cm-nylon-sling.aspx) or just the wider dyneema ones.

In reply to CurlyStevo:



But you can resling a hex/nut yourself with dynema.

I put a body weight bounce on both sides of the knot on each strand by using a rope clamp and molegrips.
It is surprising how much tighter you can get the knot compared to just tightening a sling with two karabiners and body weight.

In reply to Rick Graham:

true. that tech web I linked looks quite good for that too

In reply to CurlyStevo:

Thanks all for the responses.

I don't think I'll be making a complete rack of extenders out of cord in a hurry, but I think using +7mm short term as an extender is still a safe bet.

That table is interesting - cheers