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Chockstone Forum - General Discussion

General Climbing Discussion

 Page 1 of 3. Messages 1 to 20 | 21 to 40 | 41 to 42
Author
Double, twin or single rope ...?

Bernardo
18/05/2004
2:29:51 PM
im not sure whether this has been discussed before so im just gona ask.

i have been climbign and leading for quite a few years now adn have always used a single 10.5 or 11 mm rope.
lately i have become rather interested in the twin and double rope techniques, partly due to the fact that i can get them very cheaply when im in europe visiting family.

so i was wondering what you guys thought of the different techniques, which one is more apropriate for what style of climbing adn also where i may be able to find some more information on the actual use of double adn twin ropes. i havent had any luck in finding any realy inforamtive source..


shiltz
18/05/2004
2:57:00 PM
It has been covered before somewhere but here is a good explanation I found on another web site... In summary double ropes are great for wandering trad climbs or dangerous clips on run-out "sport" routes. Twins are only really used on Alpine routes. Single ropes are the best for nice direct sport routes (less weight).


Twin ropes
Twin ropes must only be used in pairs and are clipped together into each piece of protection, as with single rope technique. The two ropes offer redundancy and thus, increased safety in the case of shock loading over a sharp edge. They are therefore especially suited for alpine climbing or demanding routes where retreat may be necessary. They offer the highest safety margin and allow full length rappels.


Double (half) ropes
Double ropes, with regard to strength and weight, lie between single and twin ropes. They only offer standard safety when they are used as a pair. But here you have the choice between twin rope technique, where both ropes run parallel through the protection and double rope technique, where the "left" and "right" ropes run separately through different protection points. This technique allows friction to be reduced in the case where protection points are widely spread and reduces impact force. This is of benefit when climbing traditionally protected routes. A belay method which enables the independent control of each rope must be used.

Bernardo
18/05/2004
3:06:35 PM
i see...
i climb mostly at arapiles adn similar areas, long trad routes are my preference, so im guessing double ropes isnt that bad an idea.

there question here would then be: what kind of ropes are usualy used? 8mm? or is that for twin rope technique?
dalai
18/05/2004
3:13:53 PM
Read through http://www.chockstone.org/TechTips/TwoRopes.htm Has some good information.

shiltz
18/05/2004
3:15:40 PM
Double ropes are normally in the 8-9mm range. They are marked as being double (half) ropes and rated as such.

Bernardo
18/05/2004
3:18:49 PM
excelent..thank you very much..
any suggestions where id be able to find some information on half rope technique?

manacubus
18/05/2004
3:30:20 PM
If there's one place I absolutely love to use double ropes, it's at Arapiles!

While we're at it, check out these new belay devices that have been designed specifically with double ropes in mind:

Petzl Reversino (7.5 mm to 8.2 mm)
http://www.backcountrystore.com/store/PTZ0066.html?AFC=CJDataFeed

DMM Bugette (7.5 mm through to 9.5 mm)
http://www.northernmountain.com/NMSMain.asp?Option=Detail&ID=Bugette&Dept=CL&Cat=CL9&SubCat=CL91&Detail=Yes

Very cute.

Bernardo
18/05/2004
3:35:44 PM
cool, thanks guys..
i like that reversino, i already have a reverso though..so i think that a reversino is kinda unnecessary, its not as versatile as the reverso..

Andrew_M
18/05/2004
4:42:28 PM
While the topic of doubles is being discussed, I've got another question for the regular double rope users. I recently started using doubles and had a good sized fall (about 6-7m) onto a single double rope (the second rope didn't come into play). There was about 10-15m of rope out, so what's that, about a 0.5 fall factor. I wouldn't think about retiring a single rope after a fall like that, but doubles are only rated for 50kg(??) and I'm a hefty 90. I've been climbing on it since then and I don't feel unsafe, but then again I don't necessarily want to inflict my personal risk threshold decisions on partners, so any of you regular double-rope users have an opinion on this one?

Cheers,

Andrew

shaggy
18/05/2004
4:59:09 PM
When they do the tests, they rate the ropes at a particular number of falls, using a 55 kg weight, for a factor 1.7 fall. Your fall, even though the weight is much greater, is much lower than a factor 1.7, therefore you didn't even come close to taking away a life of the rope. My doubles are rated at 17 falls (each), I would still probably take off one fall from the appropriate rope, just for peice of mind.
gfdonc
19/05/2004
12:57:24 PM
One point that needs to be added on this thread is that double ropes complicates things a lot for the belayer. That is, part of your decision to use doubles depends on who is belaying you. If they're not comfortable, you won't be safe.


climbau
19/05/2004
3:43:16 PM
I was always under the impression that when climbing on doubles, that you can start the route with both lines clipped to the same piece of pro with the same biner. But once you started seperating the ropes (e.g. red to right, blue to left) off to differing pieces of pro then you could never clip them back into the same biner due to the risk of excess friction. But you could put two runners onto the same piece of pro.
Can anyone confirm this?
dalai
19/05/2004
3:49:26 PM
Theory suggested to me years ago is that at the higher runner where both are clipped together, there may be differing lengths of rope out (i.e. one rope isn't as direct to that point). If you fall the ropes may move at different speeds generating heat damaging the ropes as they run against each other.

climbau
19/05/2004
3:53:04 PM
Yeah, thought it made sense.
But I have never found anything written about such an issue.
Thanx for the response.
M
19/05/2004
4:05:06 PM
\ a good sized fall (about 6-7m) onto a single double rope (the second
>rope didn't come into play). There was about 10-15m of rope out, so what's
>that, about a 0.5 fall factor.

This also does not take into account dynamic factors such as slippage through the belay device and movement of the belayer which further reduce the forces on the rope.

I have always wondered why double ropes were only tested at 50kg when in practice a lot of falls will only weight one rope. Its obvious that they dont need to take as many falls as there is some redundancy and some falls will weight both ropes. Also in practice ropes dont wear out because of high factor falls which are pretty rare. maybe manufacunlturers feel that a low number of falls at a higher rating would concern people without reason
dalai
19/05/2004
4:09:46 PM
Another fear with the twin rope technique by some - was a popular technique in Europe with no accidents attributed to this technique that I know of so probably unfounded. Is that by having both ropes running through one karabiner, the load may not be close to the spine of the krab and load closer to the gate where it is potentially weaker.

As for articles, there must be something out there to confirm all this.

Cheers Martin

shaggy
19/05/2004
4:28:03 PM
The only reason you shouldn't clip both through the one peice of gear is as follows:
The rope system is designed to absorb the forces involved with a fall via the elongation properties of the rope. The amount the rope elongates is directly proportional to the forces exerted on both the falling climber and the piece of gear clipped last. If you clip both ropes together, two ropes are taking the fall force, and therefore each rope is exposed to half the force, which in turn results in the rope only elongating half the amount, and thus exerting twice the force on the climber and gear.
Loads of theory involved, but basically:

"If you clip both ropes, then fall, you will experience twice the forces as if you only clipped one."

Confusia has spoken

shmalec
19/05/2004
4:30:41 PM
dalai wrote:
>, there may be differing lengths of rope out (i.e.
>one rope isn't as direct to that point). If you fall the ropes may move
>at different speeds generating heat damaging the ropes as they run against
>each other.

I've seen this mentioned a couple of times on chockstone. Seems unlikely to me that this could generate much heat. There can be no relative movement between the two ropes at the climber or belayer. Maybe possible in theory to get a bit of movement in the middle somewhere but generating enough heat to damage a rope sounds a bit suss.

I read somewhere that it is advisable to clip both ropes through the first runner to avoid a high fall factor on a single half rope. Sounds like a good idea to me unless you traverse straight from the belay.

shaggy
19/05/2004
4:35:48 PM
On 19/05/2004 shmalec wrote:
>I read somewhere that it is advisable to clip both ropes through the first
>runner to avoid a high fall factor on a single half rope. Sounds like a
>good idea to me unless you traverse straight from the belay.

This is probably the worst thing to do, double ropes are more than capable of with standing the high forces involved with high factor falls, they're designed to do that.
But gear placements aren't, and by clipping both together you are doubling the forces on a single piece of gear.
The only reason to clip both together in the first piece, is, if your not going to fall, and it provides you with a good multi directional.

Rich
19/05/2004
5:11:21 PM
On 19/05/2004 shaggy wrote:
>On 19/05/2004 shmalec wrote:
>>I read somewhere that it is advisable to clip both ropes through the
>first
>>runner to avoid a high fall factor on a single half rope. Sounds like
>a
>>good idea to me unless you traverse straight from the belay.
>
>This is probably the worst thing to do, double ropes are more than capable
>of with standing the high forces involved with high factor falls, they're
>designed to do that.
>But gear placements aren't, and by clipping both together you are doubling
>the forces on a single piece of gear.

and earlier..

>The amount the rope elongates is directly proportional to the forces exerted on both >the falling climber and the piece of gear clipped last.

And the elongation is half that what it would be if it was only one rope so wouldn't the force be pretty much the same as one rope, ie 2 x1/2 =1?

 Page 1 of 3. Messages 1 to 20 | 21 to 40 | 41 to 42
There are 42 messages in this topic.

 

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