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Chockstone Forum - General Discussion

General Climbing Discussion

 Page 2 of 3. Messages 1 to 20 | 21 to 40 | 41 to 48
Author
Cordalettes

trent
29/09/2003
11:46:07 AM
i read an article a little while ago and for the life of me cant find it now, that outlined the results of an Engineering Masters Thesis that investigated the most ideal material for a cordalette.He tested 6,7 and 8mm accessory cord as well as 5.5, 7 and 8mm spectra/gemini style materials and found that if you consider wear, required strength, knotablity, cost 7mm nylon(perlon) accessory cord rates the best. The thing that i love best about 7mm cord is that it can be tied into a prussic knot to be used in a variety of self rescue situations where as ive always experienced slippage with spectra. also i find that being able to tie 7mm cord with a variety of knots (not just triple fishermans) means that it is much more versatile. I dont let cost sway my opion when it comes to pieces of equipment like cordalettes so its not the fact that they are 4 times cheaper that sways me toward them.
if you consider that with a cordelette the total load is being distributed between three of four placements than you would need a load in excess of 3000-4000kg to even appoach the quoted breaking strain of the 7mm cord and considering that these strengths are lower that the real life max load rating of the cord, i think its safe to say that 7mm is way strong enough.
Another thing i always consider when discussing cordalette material is that the only time a cordalette is going to be loaded is either by a seconder falling (with relatively minimal strain on the anchor matrix) or in a factor 2 lead fall. to eleviate the latter i always put a piece in straight of the belay or if there is none i use the highest/strong piece of gear that is in the belay as my first piece.
Its interesting to hear that many of you use 8-10m long cordalettes. mine are all either 6 or 7m long and i would usually extend placements with slings if required.

Rich
29/09/2003
1:09:51 PM
i use 6m 5.5 spectra and i have used it for prussiking just the other day and it was fine although there were a few loops more than usual cos it was doubled over to make it shorter.

and re more force on pro.. well all static cord will put more force on the anchors than if u were using dynamic rope but as trent said except in the case of a factor 2 fall there will not be a whole lot of force on the anchors anyway (relatively speaking) and i'd say that the cordelette would not be the weakest link anyway.
DC
2/10/2003
5:59:22 PM
I just replaced my 7mm cord as I was using it for top roping and when taking the anchor down found that it had rubbed down to the core. Although this was probably my own fault my replacement cord is 8mm and 12m long compared with 7mm and 10m long. I must admit that I have noticed a little bit of extra weight, but I have found having the extra width and length has made a lot of set ups at Araps much easier due to the distance between the edge and placements. If you are using your cord in a loop and equalising off three pieces then tying an over hand knot then effectively you have 6 lengths of 1000kg rated rope to the knot and three loops to clip your screw gates in. I'd be more concerned about the quality of the placements than the strength of the cord. I have used this method on up to 5 placements when the gear has been poor.

Scratch
2/10/2003
6:18:21 PM
This was quite interesting..
http://www.mountaineers.org/climbing/Reference/Cordelette.html
Peter
2/10/2003
10:30:08 PM
Chris is not weight that snaps a biner, it is the shock load, think of a bit a wood, heaps can stand on it without breaking, but one person stamping on it will snap it.
I woult use ANYTHING without a known strength rating.
kieranl
2/10/2003
11:11:59 PM
DC, what caused the anchor to be rubbed to the core?

fruityarse
3/10/2003
12:29:40 PM
thanks scratch - very interesting!

BTW - what is a shoinker?

IdratherbeclimbingM9
8/10/2003
10:57:38 PM
On 26/09/2003 fruityarse wrote:

>- would not a smaller diameter rope
>(irrespective of material) place more stress on the pro? I make that presumption
>on the assumption that there would be less elongation with these smaller
>diameter ropes as opposed to a normal rope.

I use spectra for my cordellette. Have used it for years and it wears well. In fact I have only ever once managed to abrade through the sheath of a piece of spectra which was slung on a modified bong (huge piton) for use as pro in an offwidth crack.

Spectra is static (no stretch) so the impact it may sustain is directly transferred to the anchor pieces, however the belay device and rope elongation should have made that force manageable by that time.

For multipitch aid climbs I have used spectra and also 7mm and 8mm accessory cord for cordalettes. I prefer the spectra from this experience, and only take the spectra one when free climbing. It is 'double length' though I only use half of it mostly, but have found the extra length very useful on adventure climbs.
I prefer it double length because on an aid climb I can generally set two 'power (anchor) points' (separated horizontally) off the same 3 anchors (bolts or whatever). This lets me hang the gearbag / partner(s) / ropebucket off to the side and makes hanging belays more user friendly when managing heaps of gear. Envisage two cordellettes set off the same anchors using the same (locking) krabs. Being only one cordalette gives the same redundancy ( I have it knotted into 2 loops) but greater flexability if needed to extend out to remote anchor points.

If the anchor composite is still marginal and you don't want a direct force transferred to it then using 'screamers' (tear stitch runners) can be a great help.

IdratherbeclimbingM9
8/10/2003
11:12:48 PM
On 27/09/2003 Scratch wrote:
>anyone use 7mm cord tied as a snake cordellete? would it be strong enough
>(ok, now that i've read the above, I should ask "is 1000kg strong enough")?

If you have (at least) three (like the webolettes) set to bombproof anchors, then the answer is "probably" ... (it depends on the load envisaged); but why would you bother?
It seems to me that you loose the advantages of a cordellete and gain the encumbrances of additional weight etc for less overall strength??

Tel
23/03/2004
11:05:34 PM
I am realising this is an old discussion, but didn't want to start a new thread seeing it is about the same thing , I think.Previous discussion mentions testing strengths ect.. well maybe this will be useful.... possibly too old though yr 2000.

http://www.xmission.com/~tmoyer/testing/High_Strength_Cord.pdf
Comparative Testing of High Strength Cord.

Now about those Cams ...Re: who is the manufacturer. It was suggested that the slings were on the dodgy side and so should be replaced. The advice, which I took, was to use spectra cord, which I did, and then was told to use a double fishermans knot. So after spending 27 dollars for cord and then a substantial amount of time doing this I now have new slings.
After what I thought was an excellent achievement( never tied a fishermans before) I thought a read in the good book of farming (rockclimbing getting started G Tempest) to cap the night off. I then recoiled in horror wherein it states that spectra requires a triple fishermans knot.
So basically what I am wanting to know is ....have I been led up the garden path and dropped down the wishing well, with regards to the info I have been given, or, is a double sufficient.

doomed to be a bumbly I am sure
terry

IdratherbeclimbingM9
24/03/2004
9:21:17 AM
I use triple fishermans knot on spectra, as it is a thin and slippery cord.
I heard Bluewater or Spelean did tests on knots in spectra and this was their recommendation as well.
The extra wrap can't hurt and it could be the difference between coping and failure of the knot. I still leave tails about (minimum) 3cm after the third wrap. The tails can be taped if deemed a nuisance.
In the real world many other factors would have equal bearing on the result; eg gear placement, protection type etc.

Tel
24/03/2004
9:53:39 AM
On 24/03/2004 A5iswhereitsat wrote:
>
>The extra wrap can't hurt and it could be the difference between coping
>and failure of the knot. I still leave tails about (minimum) 3cm after
>the third wrap.
Thanks A5, problem is with the lengths I have made I can no longer retie them with an extra loop to make it a triple as the slings would then be impracticle. So it means having to buy more spectra, I know it is a simple thing buy more or risk knot failure. What pisses me off is that I fell into the trap of taking someones word as gospel figuring that they would know more than I and as a consequence have wasted money and I have five lengths of spectra that are now unusable.

mousey
24/03/2004
12:04:20 PM
the spectra isn't neccessarily unusable- how long are they? i often find uses for stuff like that- if the spectra is less than about 20cm long you can just use it for tying on pieces of gear or making extra gear loops on your crag pack etc.
be creative

shmalec
24/03/2004
1:31:08 PM
the elongation thing is a good point.
a small movement in direction of loading can mean the diff between good equalisation and all load going onto one piece.
I use a 5.5mm spectra one and find that you have to be very careful to get the direction right. no other dramas with the stuff.
the other thing to remember is that they don't usually see the same loads as your climbing rope. when belaying a seconder there is little shock loading and when belaying a leader, much of the shock load goes into shifting the belayer.

IdratherbeclimbingM9
24/03/2004
1:37:24 PM
On 24/03/2004 shmalec wrote:
>(snip) when belaying a seconder there is little shock loading
>and when belaying a leader, much of the shock load goes into shifting the
>belayer.
Unless of course you are belaying directly off the cordalette.

Mighty Mouse
>if the spectra is less than about 20cm long you can just use it for tying on pieces of >gear or making extra gear loops on your crag pack etc.
True.
Even with a triple fishermans my finished loops on my 'homemade spectra slung' cams are only about 10cm. I reckon I could still get by with loops half that size.

Tel
24/03/2004
2:04:27 PM
On 24/03/2004 A5iswhereitsat wrote:
>.
>True.
>Even with a triple fishermans my finished loops on my 'homemade spectra
>slung' cams are only about 10cm. I reckon I could still get by with loops
>half that size.

ok maybe this is not so disasterous.... each length is around 70 cm, loops are around 17-20 cm( it was suggested to make the loops around 20cm). So as far as the loops is it a case of horses for courses. Am I being excessive with loop size ?

postscript: taking into considerations A5's post I redid one of the slings with a triple, loop size is approx 10 cm, and the tag ends are around 2.5 cm, is this sufficient, I jsut want them as close to right as possible
thanks
tel

IdratherbeclimbingM9
24/03/2004
2:21:22 PM
On 24/03/2004 Tel wrote:
>loops are around 17-20 cm( it was suggested to make the loops around 20cm). So
>as far as the loops is it a case of horses for courses. Am I being excessive
>with loop size ?
You are right re horses for courses.
Re excessive; If my loops were that large I would have a half-twist loop-fold in them to rack them smaller but allow extension if required.
While the spectra is new it is often stiff. This translates into less flexability = more potential to 'walk' or lift out pro.
Longer = more flexability = better ?
Overhanging sport route would probably require less loop length. Trad wandery routes, you would need to extend them.
The free-climbing I prefer/do means about 80% of the time I extend my pro with longish runners, but in aid I generally prefer minimum extension as every placement is trying to gain height, as long as I have some bomber bits every now and then, which I may extend 'in passing' to help ensure they stay put.
gfdonc
24/03/2004
4:19:16 PM
Ummm .. all of the above was fascinating, thanks guys.
Some advice now, I have a trad favourite #3 Chouinard hex (yes, fairly old) that was on 7mm cord (very tight fit, took pliers to pull out). Relaced all my chocks recently, and tried to get some 'new' 7mm cord through but it would not fit.
So it now has 6mm. Is this good enough? Should I use Spectra instead? Based on the articles I've read I'm not confident about the benefits in terms of strength over use.

IdratherbeclimbingM9
24/03/2004
4:36:54 PM
On 24/03/2004 Tel wrote:
>postscript: taking into considerations A5's post I redid one of the slings
>with a triple, loop size is approx 10 cm, and the tag ends are around 2.5
>cm, is this sufficient, I jsut want them as close to right as possible
Its like climbingjac said the other day; ... there is not necessarily a right or wrong way to climb!
What you have got should be good for most situations.
Tip. Make sure the knots are dressed properly. Clip off the loop to a rafter (or similar) and hang off a sling clipped to it. While bodyweight is applied pull the tails tight with a pair of pliers! (Reverse the loop if you have to to access the 2nd tail).
You should then have no worries about the knots slipping.

Tel
24/03/2004
4:41:31 PM
Thanks, appreciate all your thoughts A5....
terry

 Page 2 of 3. Messages 1 to 20 | 21 to 40 | 41 to 48
There are 48 messages in this topic.

 

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