singles/twins/doubles. good reading, your opinions?
tradkelly
preposted. I prefer new singles, my ice and desert stuff is old
singles 'less I'm with someone using doubles. I didn't think about
using twins (halves) when I followed a rock route, tho this might make
that seem unsound. Looking for other opinions. What's everyone
think?
cheers
tradkelly
http://www.geocities.com/tradkelly
From; Helmut Microys, National Delegate to the UIAA Safety Commission
for the USA and Canada.
The UIAA standard deals with three different rope types: single, half
and twin. In the UIAA drop test the single rope is tested with an 80
kg mass, a single strand of half rope with a 55 kg mass and both
strands of a twin rope with 80 kg. The single and half ropes must
sustain at least five falls and twin ropes at least twelve to pass the
standard. There are also differences among these ropes for elongation
and impact force (single and twin < 12 kN; half ropes < 8 kN).
Single ropes are obviously designed to be used in a single strand.
Half ropes, or double ropes, are designed for (aid) routes with many
runners at close spacing and are then clipped in alternately. The idea
was to reduce friction, particularly in the days, when climbers used
only carabiners and no sling extensions (the rope went zig-zag). These
ropes should not be used in this way (i.e. clip in alternately), as
often happens these days, for regular routes with runners further
apart. Keep in mind that the rope is not tested with an 80 kg mass. A
single strand of half rope, when new, may just hold one fall with such
a mass.
The twin rope was designed to be used in the double strand and both
strands must be clipped in every runner. Generally these ropes have a
diameter of only 8 mm. The benefit of a twin rope is its essential
safety and the advantage in the mountains for a full length rappel.
Present day ropes will not break at a runner or at the tie-in knot of
the leader in a fall. This does not even happen with very old ropes. A
rope fails when a sharp edge cuts it. As a rope is used, the capacity
to hold a fall over a sharp edge decreases. Generally speaking, a rope
which holds many falls in the UIAA drop test will resist cutting
better than a rope which hold fewer falls.
A half rope used singly is, therefore, much more likely to be cut than
a single rope. It could potentially be used for all climbing, but you
better not plan on falling off. A twin rope is much safer, because of
the higher capacity and the redundancy (only one strand may be cut).
Using half ropes like a twin, clipping both strands in every carabiner
is, of course, the safest solution (a pair of decent half ropes,
tested like a twin rope will most likely hold over 30 falls).
The maximum allowable elongation for half ropes (10 %) is indeed
larger than for single or twin ropes (8 %), but this would hardly be
noticeable in most fall situations. Elongation is more often than not
only a problem for a second with the rope out 100 feet. An 80 kg
climber could drop eight feet under body weight even though the rope
contains no slack.
Final advice: do not use your half rope as a single strand and when
the runners are further apart, clip both strands. You only live once.
Ice climbers in USA routinely use the double rope technique placing
gear (ice screws) very sparsely using half ropes. So:
1. In this situation is the second half rope for backup purposes?
On pure ice faces and water falls, there are generally no sharp edges
and the danger of cutting a rope are greatly reduced. A new half rope
may be reasonably safe, although I would advice against it when there
is a lot of dry tooling and runners are still far apart (I personally
would not climb on it regardless of the situation). In the latter case
it may be called a back up rope, because of cutting on an edge.
When the climber is on a water fall or smooth ice face, where there is
no friction to speak of, the question can be asked, why not climb with
a single half rope and clip all the protection. The result would be
pretty well the same in a fall situation as having two ropes. If the
rope breaks, it is because the fall energy was beyond the capacity of
the rope. With two ropes clippped alternately and the runners the same
distance apart, if the first rope breaks at the first runner and the
second will fail on the one below.
One of the reason for two ropes on waterfall ice is that one must
generally rappel and two ropes get you down faster and cheaper.
2. If I were to clip both half ropes together into one carabiner,
wouldn't that increase the load on the protection beyond safety levels
for the carabiners and protection as opposed to a single or twin
setup?
Using two half ropes clipped in together will produce forces on the
protection higher than when using a single rope. Twin ropes act like a
single rope.
The forces in the system are, however, determined by the belay method.
Any modern dynamic belay method will limit the forces inherent in the
device. The impact force (the maximum obtained during the UIAA drop
test) and provided on the rope tag, is of no consequence. Thus the
forces generated, particularly in a near frictionless system, which
may occur on a waterfall, are not very high.
These forces are, as a rule, vastly below the capacity of any
equipment (carabiners, ice screws, pitons, slings, etc.). The problem
lies in the holding capacity of the ice screw, piton, nut, etc. If the
ice is of poor quality, a screw capable of holding 20 kN in good ice
is no more helpful than a coat hanger, if that is the holding power of
the ice.
So in a scary, poor ice, situation the only thing, which may be of
value, is to put protection at very close spacing. That unfortunately
is often not possible. But it would help to clip both ropes in the
last bomber protection.
3. How soon/often do I have to retire the half ropes provided I take
falls on them (very few climbers are 55kg and under, I am 90kg)?
If there are no sharp edges, a rope could most likely be used until
the mantle starts shredding and can no longer be used in a belay
device. This applies mainly to a single rope. The half rope is simply
not designed to take major leader falls. But as mentioned before, the
forces in the system are determined by the belay device. With a
properly working dynamic belay, not much will happen to the rope. Do
not belay with a static belay device such as a Grigri, which should be
used for top roping only.
4. Is the conclusion that one just should not buy or use half ropes?
Or they are still manufactured for cases where falls are not dead
vertical, in alpine terrain wit lots of rope drag? Or perhaps they are
manufactured out of inertia and for marketing purposes?
They are most useful in alpine terrain where lots of friction may
result, if the ropes are clipped in all the runners. An additional
advantage is that there is a backup rope of sufficient capacity,
should a rope be cut by rock fall. Finally the rope offers redundancy
in the case of sharp edges. Double ropes have more holding capacity
over an edge to start with. Even if both ropes run over the same sharp
edge, it is less likely both get cut because one will get loaded more
than the other. In a retreat, being able to rappel the full length of
the rope is invaluable.
The other option is to climb with twin ropes. Extra edge strength
(remember twelve UIAA falls minimum), redundancy, lighter ropes, in a
severe case the option of clipping in alternately, rappel convenience.
I personally have not owned a single rope for at least 25 years. I
used to climb with two half ropes and clipped them together when it
was suitable.
Now I climb with twin ropes. I use these ropes in any terrain.
Dingus Milktoast
>
>Looking for other opinions. What's everyone
> think?
I have and use a set of doubles for ice and alpine work. I
don't really use them for cragging at all. I got an
incredible deal on them and based upon my use, they will
last a long time. I treat them like a single as far as
protection goes. It was once argued here that this was an
unsafe practice due to the increased load and the potential
for friction between the two ropes during a fall. Now I've
taken numerous falls on them and noticed none of these
dreaded characteristics. I corresponded with a well known
climbing equipment test engineer (who is of similar girth to
me, and uses the same techniques AND actually tests for this
sort of thing). He concurred with my gut feeling that these
concerns were negligible.
But I have read with interest the rope usage cited in
particular by Slime and Nate. Say a 9.1 or similar single
and the lightest rap rope you can tolerate, 7mm or so. The
package weighs less overall. The leader isn't hauling up so
much ropage at the end of a pitch.
Recently I have acquired a slim 9 (another sweet deal!) and
will soon get a rap rope to go with it. I like cake. I eat
it too!
Never have used twins though. Never quite saw the point...
guess I still don't.
DMT
Brutus of Wyde
> particular by Slime and Nate. Say a 9.1 or similar single
> and the lightest rap rope you can tolerate, 7mm or so. The
> package weighs less overall. The leader isn't hauling up so
> much ropage at the end of a pitch.
>
> Recently I have acquired a slim 9 (another sweet deal!) and
> will soon get a rap rope to go with it. I like cake. I eat
> it too!
>
> Never have used twins though. Never quite saw the point...
> guess I still don't.
I used my Ice Floss ropes for the first
time this winter up in Canada. I have to
say that I prefer the twin system to
the half-rope system.
The thing I mainly disliked about
half ropes was that I had difficulty
(when using in accordance with
established safe practices) keeping
both ropes from behind my legs. Twins
I use like a single rope: both
are clipped into each piece. Detractors
of twins will tell you that
this increases impact force. I should
note that when I have used 'em for ice,
I use load limiters.
Like generals in traditional military,
who are always preparing to fight the
*last* war that they were involved in,
I am always preparing gear for the climb
I just completed:
I originally purchased the twins
after spending three weeks on the
Tiedemann and Bravo glaciers:
Multi-day glacier climb with crevassed
terrain, icefalls and snow-slogging
up to the Cauldron, followed
by a three pitch mixed rock and snow
headwall, then more glacier
slogging, up to mixed rock and ice,
then a final multi-pitch rime-
encrusted summit tower. Weight of
every item needed to be kept to
the absolute minimum, and we needed
to be able to make full-rope-length
raps off the summit, building our
own rap stations (i.e. leaving gear)
This system weighs less than the 9.1mm-
plus-7mm combo. It has its applications,
where weight is critical to the success of the
venture.
If you're considering taking titanium
pitons, cams, and ice screws to reduce weight,
if you've replaced half the cams with tricams and
passive nuts that can be pounded into icy cracks,
if you've stripped your rack to the absolute
minimum number of carabiners, and those
are neutrinos, if your titanium cooking pot
is also your shovel, if you are weighing your shoulder-
length runners, and taking just enough fuel to melt
snow for drinking water, on long, hard alpine in the
way outback with multi-rope rappels,
twin ropes may be the next step in lightening the
load.
Brutus
Julie
> for the USA and Canada.
>
> runners at close spacing and are then clipped in alternately. The idea
> was to reduce friction, particularly in the days, when climbers used
> only carabiners and no sling extensions (the rope went zig-zag). These
> ropes should not be used in this way (i.e. clip in alternately), as
> often happens these days, for regular routes with runners further
> apart. Keep in mind that the rope is not tested with an 80 kg mass. A
> single strand of half rope, when new, may just hold one fall with such
> a mass.
If I read correctly ... he claims that for strength/edge reasons, doubles
should rarely, if ever, be clipped into separate/alternate pieces; they
should essentially be used as (stronger) twins (that would explain why he
only climbs with twins now). This, though, is the first I've read of such a
strong claim against what I've seen/known/read as 'double rope technique'.
So here's a question for the Physics Patrol: if I'm clipping alternate
pieces with alternate strands of doubles, exactly how far (in terms of
distance from the last piece, or fall factor, or whatever measure) is
'further apart'? In other words, at what length/point do I need to think
about clipping both strands, for strength reasons?
JSH
Brutus of Wyde
> I didn't think about
> using twins (halves) when I followed a rock route, tho this might make
> that seem unsound.
The source you yourself quote below distinguishes between twins
(used together as a single rope) and half (aka "double") which
are typically clipped alternately.
So what, exactly, are you talking about?? :)
> The UIAA standard deals with three different rope types: single, half
> and twin. In the UIAA drop test the single rope is tested with an 80
> kg mass, a single strand of half rope with a 55 kg mass and both
> strands of a twin rope with 80 kg.
> Single ropes are obviously designed to be used in a single strand.
> Half ropes, or double ropes, are designed for (aid) routes with many
> runners at close spacing and are then clipped in alternately. The idea
> was to reduce friction, particularly in the days, when climbers used
> only carabiners and no sling extensions (the rope went zig-zag). These
> ropes should not be used in this way (i.e. clip in alternately), as
> often happens these days, for regular routes with runners further
> apart. Keep in mind that the rope is not tested with an 80 kg mass. A
> single strand of half rope, when new, may just hold one fall with such
> a mass.
Hmm. Didn't I have concerns regarding this very thing in the
discussion
that is currently recorded in Dawn's FAQ? Ken? Dawn?
> The twin rope was designed to be used in the double strand and both
> strands must be clipped in every runner. Generally these ropes have a
> diameter of only 8 mm. The benefit of a twin rope is its essential
> safety and the advantage in the mountains for a full length rappel.
> A half rope used singly is, therefore, much more likely to be cut than
> a single rope. It could potentially be used for all climbing, but you
> better not plan on falling off. A twin rope is much safer, because of
> the higher capacity and the redundancy (only one strand may be cut).
> Using half ropes like a twin, clipping both strands in every carabiner
> is, of course, the safest solution (a pair of decent half ropes,
> tested like a twin rope will most likely hold over 30 falls).
Unless one considers impact force:
> Using two half ropes clipped in together will produce forces on the
> protection higher than when using a single rope. Twin ropes act like a
> single rope.
Actually, no. Twin ropes as a general rule have a higher impact force
than most single ropes. They also hold more high factor falls.
> So in a scary, poor ice, situation the only thing, which may be of
> value, is to put protection at very close spacing.
The only thing? How about Screamers or other load limiters? How
about self-equalizing placements in combination with screamers?
> but that unfortunately is often not possible.
> But it would help to clip both ropes in the
> last bomber protection.
How about what I do: Place TWO good screws at
your last good ice and good stance. ("last bomber
protection") Load limiters on each. Clip half,
twin or single rope in accordance with standard
half, twin, or single rope technique. Sure,
sometimes ya can't, but no hard-and-fast rule
applies to all situations (except DON'T FALL (TM).
It's a BIG DEAL (TM). You could DIE (TM).)
Where two bomber pieces is not possible, yes,
it does make sense to clip both half strands.
> 3. How soon/often do I have to retire the half ropes provided I take
> falls on them (very few climbers are 55kg and under, I am 90kg)?
>
> If there are no sharp edges, a rope could most likely be used until
> the mantle starts shredding and can no longer be used in a belay
> device. This applies mainly to a single rope. The half rope is simply
> not designed to take major leader falls. But as mentioned before, the
> forces in the system are determined by the belay device. With a
> properly working dynamic belay, not much will happen to the rope. Do
> not belay with a static belay device such as a Grigri,
Yaah, like, everyone here routinely uses the grigri for belaying on
double ropes and twin ropes. What is this guy smoking, eh? :)
> which should be used for top roping only.
Hmmm. Can't say I agree that the grigri is only for top roping.
Good device for belaying the leader on walls while hauling and setting
up the portaledge, etc. Of course, read the Disclaimer (TM)
> 4. Is the conclusion that one just should not buy or use half ropes?
> Or they are still manufactured for cases where falls are not dead
> vertical, in alpine terrain wit lots of rope drag? Or perhaps they are
> manufactured out of inertia and for marketing purposes?
> They are most useful in alpine terrain where lots of friction may
> result, if the ropes are clipped in all the runners. An additional
> advantage is that there is a backup rope of sufficient capacity,
> should a rope be cut by rock fall. Finally the rope offers redundancy
> in the case of sharp edges. Double ropes have more holding capacity
> over an edge to start with. Even if both ropes run over the same sharp
> edge, it is less likely both get cut because one will get loaded more
> than the other. In a retreat, being able to rappel the full length of
> the rope is invaluable.
>
> The other option is to climb with twin ropes. Extra edge strength
> (remember twelve UIAA falls minimum), redundancy, lighter ropes, in a
> severe case the option of clipping in alternately,
Whoa. Clipping TWIN ropes alternately? wonderful advice.
Just wonderful. No, thanks.
> rappel convenience.
>
> I personally have not owned a single rope for at least 25 years. I
> used to climb with two half ropes and clipped them together when it
> was suitable.
>
> Now I climb with twin ropes. I use these ropes in any terrain.
Personally I would not follow this fella's advice if you paid me.
My standard on long trad, walls, and backcountry is still single rope.
When taking a pack, (or haul bag) the second lighter rap line serves
as a haul line as well. Not possible with twins or doubles, thus its
the lightest solution for many specific situations. When fixing ropes,
in the
backcountry, the thinnest I will accept is a half-rope (aka double)
I consider a single strand of twin to be too thin, due to the
possibility
of cutting over an edge while sawing up and down as I jug, similar to
what happened to Harlin on the FWA of the Eiger NF (7mm jug rope cut).
I say different gear for different situations. Twins, doubles, and
singles
all have their place. Twins may be best for everything *you* do. Or
halfs (doubles.) Or single ropes. If your climbing ranges from roofs
and wandering
routes to steep featureless ice to walls to fixing ropes on new remote
routes
in the backcountry, to alpine, to sport, to bouldering, to gym routes,
you may find that a quiver of different types and lengths of ropes is
best, and to select for each climb based on your anticipated needs.
Short on cash? then get the rope most suited to the kind of climbing
you typically enjoy.
Just my two ascents' worth.
Brutus
Guido
> I say different gear for different situations. Twins, doubles, and
> singles all have their place.
Yup. Just like skis, boots, or packs, no one rope best suits all
situations. I manage a cellar-full of ropes in various states of wear
including end-of-roll short lengths of 10.5 for TR'g small crags or
protected scrambles in the hills, and retired 11's for cleaning prospective
routes on rainy days. I select a system which meets the needs of the
day/trip/challenge, picking ropes just like assembling a rack du jour.
Despite objections to the contrary, theory and practice frequently diverge,
allowing individual judgement to prevail. Factors like cutting over an edge
or handling characteristics may be the priority for some applications in the
backcountry, whereas elongation under load or mantle weave/durability may
dictate the choice for a top rope at the local practice crag.
Finally, despite the criticism posted, I have never felt uncomfortable using
two 8.8's either in the hills, or on long routes at a challenging grade (for
me), whether alternating or clipping both ropes into gear as I go. In the
backcountry, I prefer a 10 lead rope paired with an 8- second rope, but
frequently trust to two 8.8's instead because they're long in my quiver.
It's nice to have choices. And our choices keep evolving.
Guido
Ken....@cs.cmu.edu
> > Half ropes, or double ropes, are designed for (aid) routes with many
> > runners at close spacing and are then clipped in alternately. The idea
> > was to reduce friction, particularly in the days, when climbers used
> > only carabiners and no sling extensions (the rope went zig-zag). These
> > ropes should not be used in this way (i.e. clip in alternately), as
> > often happens these days, for regular routes with runners further
> > apart. Keep in mind that the rope is not tested with an 80 kg mass. A
> > single strand of half rope, when new, may just hold one fall with such
> > a mass.
>
> Hmm. Didn't I have concerns regarding this very thing in the
> discussion
> that is currently recorded in Dawn's FAQ? Ken? Dawn?
Here's the theory I have championed in the past: When climbing on
doubles if one rope breaks it will have absorbed enough energy that
the other rope will hold. Of course, the real worry is cutting the
rope rather than breaking from overloading. When the rope is cut
(e.g. by a sharp edge), all best are off. Of course, there's also the
worry that if one rope breaks you'll fall a long, long way before the
second strand starts to catch your fall (if there is a runout).
I have a lot of respect for Helmut and recommend heeding his advice:
avoid big runouts on double ropes whenver possible - either by
clipping both ropes before a runout or choosing a different system.
Still, I think he omitted mention of a possibly significant issue in
the text that was posted. If you try to hold a hard fall on a single
half rope, chances are good that your belay device will slip
significantly. Last time this happened to me, I was using a Jaws
device and had plenty of time to look down and see that it was
properly seated as my partner rocketed earthward. I also have time to
see the rope rocket through the belay device even though I was holding
it very firmly with a leather palmed glove. As best as I can tell,
the rope continued to run through my break hand and device until the
second strand caught and added some breaking friction. In the end, my
partner completely blew out a screamer and fell 35 feet from the top
of a 36 foot high pillar ("uh... do you mind leading this one, Ken?").
Does that help?
Ken
Brutus of Wyde
> > Hmm. Didn't I have concerns regarding this very thing in the
> > discussion that is currently recorded in Dawn's FAQ? Ken? Dawn?
Ken replied:
> Here's the theory I have championed in the past: When climbing on
> doubles if one rope breaks it will have absorbed enough energy that
> the other rope will hold. Of course, the real worry is cutting the
> rope rather than breaking from overloading. When the rope is cut
> (e.g. by a sharp edge), all best are off. Of course, there's also the
> worry that if one rope breaks you'll fall a long, long way before the
> second strand starts to catch your fall (if there is a runout).
And these days, there usually is a runout.
> I have a lot of respect for Helmut and recommend heeding his advice:
> avoid big runouts on double ropes whenver possible - either by
> clipping both ropes before a runout or choosing a different system.
I agree with that advice. But a lot of what he seemed to be saying just
didn't make sense: like don't use grigri's for half rope systems...
like, Duh? Or does my medication need adjustment (again?)
> Still, I think he omitted mention of a possibly significant issue in
> the text that was posted. If you try to hold a hard fall on a single
> half rope, chances are good that your belay device will slip
> significantly. Last time this happened to me, I was using a Jaws
> device and had plenty of time to look down and see that it was
> properly seated as my partner rocketed earthward. I also have time to
> see the rope rocket through the belay device even though I was holding
> it very firmly with a leather palmed glove. As best as I can tell,
> the rope continued to run through my break hand and device until the
> second strand caught and added some breaking friction. In the end, my
> partner completely blew out a screamer and fell 35 feet from the top
> of a 36 foot high pillar ("uh... do you mind leading this one, Ken?").
Did you retire the strand? (My guess would be "no,"
considering the dynamic stop :)
Do you believe grigris should only be used for toproping?
> Does that help?
Absolutely. Glad your partner was still able to think about
climbing (vs. life on a respirator) after a fall like that.
Brutus
tradkelly
I misspoke. I only use singles when I climb or I'm the gear provider
etcetera, that's all I have.
I've been introduced to both halves and twins lately in Boulder
(halves on rock, 3-person party, followers climb simultaneously on
each half, used alternately or together as the route's pro allowed
obviously to minimize drag) (twins on ice, used like a single,
clipping both strands through pro) and when I saw the article posted I
thought it might be interesting.
I've read the thoughts in Dawn's FAQ, but it seemed like something to
also discuss in a forum again. Until someone's introduced to
something like the twins or halves concept they'd most likely ignore
that message and its' replies.
Appreciate all of your and others' input on this. It's nice to have
viewpoints and advice from multiple sources to consider in evaluating
how comfortable I am with the systems. Think for now I'll just stick
with my singles - my style (or lack thereof) and the routes I
typically climb seem well suited for singles.
Thank you! Climb safe.
tradkelly
http://www.geocities.com/tradkelly
On 5 Mar 2002 10:33:15 -0800, in rec.climbing you wrote:
>tradkelly wrote:
>> I didn't think about
>> using twins (halves) when I followed a rock route, tho this might make
>> that seem unsound.
>
>The source you yourself quote below distinguishes between twins
>(used together as a single rope) and half (aka "double") which
>are typically clipped alternately.
>
>So what, exactly, are you talking about?? :)
>
>
>Brutus
Hey Brutus,
I misspoke. I only use singles when I climb or I'm the gear provider
etcetera, that's all I have.
I've been introduced to both halves and twins lately in Boulder
(halves on rock, 3-person party, followers climb simultaneously on
each half, used alternately or together as the route's pro allowed
obviously to minimize drag) (twins on ice, used like a single,
clipping both strands through pro) and when I saw the article posted I
thought it might be interesting.
I've read the thoughts in Dawn's FAQ, but it seemed like something to
also discuss in a forum again. Until someone's introduced to
something like the twins or halves concept they'd most likely ignore
that message and its' replies.
Appreciate all of your and others' input on this. It's nice to have
viewpoints and advice from multiple sources to consider in evaluating
how comfortable I am with the systems. Think for now I'll just stick
with my singles - my style (or lack thereof) and the routes I
typically climb seem well suited for singles.
Thank you! Climb safe.
tradkelly
http://www.geocities.com/tradkelly
On 5 Mar 2002 10:33:15 -0800, in rec.climbing you wrote:
>tradkelly wrote:
>> I didn't think about
>> using twins (halves) when I followed a rock route, tho this might make
>> that seem unsound.
>
>The source you yourself quote below distinguishes between twins
>(used together as a single rope) and half (aka "double") which
>are typically clipped alternately.
>
>So what, exactly, are you talking about?? :)
>
>
>Brutus
Julie
>
> Ken replied:
>
> > Here's the theory I have championed in the past: When climbing on
> > doubles if one rope breaks it will have absorbed enough energy that
> > the other rope will hold. Of course, the real worry is cutting the
> > rope rather than breaking from overloading. When the rope is cut
> > (e.g. by a sharp edge), all best are off. Of course, there's also the
> > worry that if one rope breaks you'll fall a long, long way before the
> > second strand starts to catch your fall (if there is a runout).
>
> And these days, there usually is a runout.
>
> > I have a lot of respect for Helmut and recommend heeding his advice:
> > avoid big runouts on double ropes whenver possible - either by
> > clipping both ropes before a runout or choosing a different system.
Hey Ken,
Not to needle you, but can you please quantify 'runout' with respect to a
need to clip both ropes (I asked in another sub- of this thread)? Bigger
than FF1? > 15 feet between clips per strand?
JSH
Paul Storaasli
> If you try to hold a hard fall on a single
> half rope, chances are good that your belay device will slip
> significantly.
I often belay 8.1mm half ropes (Beal Ice Lines) in my ATC. I've heard there
are belay devices made for smaller ropes. Where can I get one? Sometimes I'll
run the ropes through two belay biners instead of one. This seems to increase
friction. Is this a good practice?
Paul
Mark Heyman
Doesn't this really come back to all the usual stuff? There really isn't a
fixed answer.
As you climb and place pro, your (possible/likely) fall factor will
decrease. Low fall factors situations don't present much of a breakage
problem, but concern over rope stretch might be appropriate.
Actually now that I'm writing I remember going through this here. A fall
factor two fall will only occur if you are caught by the belay. Then you're
going to be caught by both ropes. Ideally place a bomber first piece or
redirect, and then clip both ropes. After that, assuming the bomber piece
doesn't pull, you've eliminated the possibility of a fall factor two fall...
If you don't clip both ropes, and there is not much rope out, and the piece
has caused the lengths to be unequal, there is the possibility of falling on
a short length of one rope in a fall factor two fall. Even then, as Ken
wrote it's not likely you'd be caught by a static belay, and both ropes
would eventually come into play.
Also, when was that reference written? I think most climbers used to think
of a standard single as being 11mm. So a 9mm double only had two-thirds the
area. Currently if you compare a double 9 to a single 10 then the difference
in area is only about 1/5. So as usual it ill depends
Mark
"Julie" <jh...@fu.bu.edu> wrote in message news:a65j2p$50t$1...@news3.bu.edu...
Ken....@cs.cmu.edu
> I agree with that advice. But a lot of what he seemed to be saying just
> didn't make sense: like don't use grigri's for half rope systems...
> like, Duh? Or does my medication need adjustment (again?)
Let me know if you find some better medication - I've been using an
old version: Lime, sugar and rum.
> > Still, I think he omitted mention of a possibly significant issue in
> > the text that was posted. If you try to hold a hard fall on a single
> > half rope, chances are good that your belay device will slip
> > significantly. Last time this happened to me, I was using a Jaws
> > device and had plenty of time to look down and see that it was
> > properly seated as my partner rocketed earthward. I also have time to
> > see the rope rocket through the belay device even though I was holding
> > it very firmly with a leather palmed glove. As best as I can tell,
> > the rope continued to run through my break hand and device until the
> > second strand caught and added some breaking friction. In the end, my
> > partner completely blew out a screamer and fell 35 feet from the top
> > of a 36 foot high pillar ("uh... do you mind leading this one, Ken?").
>
> Did you retire the strand? (My guess would be "no,"
> considering the dynamic stop :)
No. We pulled the ropes through, inspecting them as much as possible
with frozen hands and I led the pitch.
> Do you believe grigris should only be used for toproping?
Of course not.
> > Does that help?
>
> Absolutely. Glad your partner was still able to think about
> climbing (vs. life on a respirator) after a fall like that.
Thanks. Tommy was toast for the rest of the day, but go to go the
next day. We went in for beers after finishing the climb.
Ken
Ken....@cs.cmu.edu
I use a Trango Jaws belay device, which provides somewhat stronger
braking action than most devices because of its "V" slots. Even so,
the rope slipped more than I imagined it would.
As for using two carabiners: I don't know of any problems, but you can
always call the manufacturer of your belay device for more info.
Ken
Ken....@cs.cmu.edu
> > > I have a lot of respect for Helmut and recommend heeding his advice:
> > > avoid big runouts on double ropes whenver possible - either by
> > > clipping both ropes before a runout or choosing a different system.
>
> Hey Ken,
>
> Not to needle you, but can you please quantify 'runout' with respect to a
> need to clip both ropes (I asked in another sub- of this thread)? Bigger
> than FF1? > 15 feet between clips per strand?
Sorry, but you're on your own here. There are no hard and fast rules.
Use your best guess to evaluate the risk of cutting one of the ropes
and consider the consequences.
Ken
Guido
> We went in for beers after finishing the climb.
Ahhh, the elixir of choice for the day's review.
'Gotta wonder how many folks "do" beer here, as it sees more reference than
concerns with marking the middle of ropes.
Guido
Guido
> As for using two carabiners: I don't know of any problems, but you can
> always call the manufacturer of your belay device for more info.
I would welcome news of a manufacturer's response, as climbers have been
doublin' up biners forever in applications for which additional friction is
advised, mindful of its "apparent" benefit, from a simple stitch forward.
Guido
Paul Storaasli
biners is good practice, I went to the BD website and looked up the ATC. The
description says:
"Locks up well with 9-11 mm ropes; with 8.1 and smaller, use two biners for
more locking power"
That answers both of my questions. I hope those who I have belayed will
forgive me.
Paul
Richard Goldstone
<snip>
> can you please quantify 'runout' with respect to a
> need to clip both ropes (I asked in another sub- of this thread)? Bigger
> than FF1? > 15 feet between clips per strand?
>
> JSH
Julie, I think there is a reasonable answer to your question, based on
the equations usually used to analyze impact loads on the ropes.
(See, for example, the Petzl site.) For those uninterested in the
reasoning, skip to the last paragraph.
The usual equations assume that ropes behave like springs, but I have
read repeatedly that tests confirm that the linear spring model is a
good approximation to reality for most climbing falls, and so the
equations have decent predictive value. (I cannot, however, claim to
have ever seen such a study.) The usual equations also assume a
static belay. Much longer falls can be held dynamically without
achieving maximum impact force tensions.
When a half rope is subjected to a UIAA drop test with a 55 kg weight,
it develops a certain maximum tension that is reported as the impact
load of the rope. What the test certifies is that the rope can
handle that impact load, however it is imposed, with a reasonable
margin of safety, usually expressed as how many test drops the rope
can sustain. For a climber heavier than 55 kg, the safe working range
of the rope would allow falls up to but not surpassing the fall
factor that would, for that heavier person, result in the rope's
certified impact force.
It is easy to compute, from the usual equations for impact loads, what
fall factors would keep, say, an 80 kg climber within the certified
impact load of a half rope. Half ropes have impact forces in the
range of 4.8 kN to 6.5 kN, and are tested with a fall factor of 1.78.
For this range of impact loads, the safe fall factor for an 80 kg
climber works out to just a little more than 1.
What this means in practice is that you can rely on a statically
belayed single half rope to catch a protected fall in which you do not
fall past your belayer. (This includes all falls on one-pitch routes,
but does not take into account any rope cutting issues.) Once you
are in a position to fall past your belayer, you either need more
protection to shorten the potential fall or need to have arranged for
both strands to be involved in catching the fall. For most routes,
the potential for falling past the belayer occurs very early in the
pitch; this is where both ropes should be involved. (Preferably, in
my opinion, separately clipped to independent or equalized protection
points)
Ken....@cs.cmu.edu
Richard,
I think you are getting lost making some invalid assumptions. The
truth is that half ropes are very strong. So strong that they hold
multiple UIAA test type falls without breaking (and with low forces on
the first drops). There is basically no chance that a half rope in
good condition will break due to excess force while holding a fall (of
an 80 kg climber) - even a factor 2 fall.
Does that mean that taking long hard falls on one strand of half rope
is a good idea? Of course not. Half ropes use up their energy
absorption ability quickly if you fall hard on them. They also have
thin sheaths which cut easily. Lastly, they can be hard for a belayer
to hold while breaking.
Use common sense, not physics, to limit the runout when using double
ropes. Clip both strands (using separate carabiners if possible) if a
runout is unavoidable. If you're looking at a long runout above bad
gear, roll the dice and clip 1 for odds, 2 for evens.
Read on for technical discussion if you are interested.
> > can you please quantify 'runout' with respect to a
> > need to clip both ropes (I asked in another sub- of this thread)? Bigger
> > than FF1? > 15 feet between clips per strand?
> >
> > JSH
>
> The usual equations assume that ropes behave like springs, but I have
> read repeatedly that tests confirm that the linear spring model is a
> good approximation to reality for most climbing falls, and so the
> equations have decent predictive value. (I cannot, however, claim to
> have ever seen such a study.)
I have seen stress-strain curves for actual climbing ropes and I agree
that using a spring model is appropriate for elongation in a single
fall. After that fall, the rope's ability to absorb energy has
changed and you need a new spring constant.
> When a half rope is subjected to a UIAA drop test with a 55 kg weight,
> it develops a certain maximum tension that is reported as the impact
> load of the rope. What the test certifies is that the rope can
> handle that impact load, however it is imposed, with a reasonable
> margin of safety, usually expressed as how many test drops the rope
> can sustain. For a climber heavier than 55 kg, the safe working range
> of the rope would allow falls up to but not surpassing the fall
> factor that would, for that heavier person, result in the rope's
> certified impact force.
I don't know how the UIAA test was developed, but I think you are
looking at it backwards! The main purpose is to ensure sufficient
energy absorbing ability, which prevents fall forces from reaching
dangerous levels. In practice, healthy ropes have ample reserve
energy absorption to catch climbing falls without breaking. When a
rope finally snaps in a test fall rig, it reaches twice the initial
fall force or higher and then only fails because of the damage done in
earlier drops. Climbing ropes simply do not break due to fall forces
and I'm not happy with the notion of "safe working range". If you
don't believe me, ask a rope manufacturer.
> It is easy to compute, from the usual equations for impact loads, what
> fall factors would keep, say, an 80 kg climber within the certified
> impact load of a half rope. Half ropes have impact forces in the
> range of 4.8 kN to 6.5 kN, and are tested with a fall factor of 1.78.
> For this range of impact loads, the safe fall factor for an 80 kg
> climber works out to just a little more than 1.
For a rope with initial test force of 5.6kN, I get a maximum fall
factor of 1.17 for an 80kg climber where the force does not exceed the
original 5.6kN. However, allowing forces to reach the UIAA half rope
test limit of 8kN, the fall factor increases to 2.6. Actual ropes
will fail well above 8kN in testing, so you see there is theoretically
ample safety margin - for a rope that has not already been damaged by
previous hard falls.
> What this means in practice is that you can rely on a statically
> belayed single half rope to catch a protected fall in which you do not
> fall past your belayer. (This includes all falls on one-pitch routes,
> but does not take into account any rope cutting issues.) Once you
> are in a position to fall past your belayer, you either need more
> protection to shorten the potential fall or need to have arranged for
> both strands to be involved in catching the fall. For most routes,
> the potential for falling past the belayer occurs very early in the
> pitch; this is where both ropes should be involved. (Preferably, in
> my opinion, separately clipped to independent or equalized protection
> points)
Ken
Richard Goldstone
Thanks for your response. Backwards thinking is my specialty, but I'm
always distressed to learn of invalid assumptions. (I take some
comfort, perhaps short-lived, in the fact that the invalid assumptions
were never identified.) In any case, I don't think we disagree about
anything. You have interpreted my comments as if they are about ropes
breaking, even though I never once mentioned the b-word. Perhaps I
went overboard in making up the term "safe working range," but I
excuse myself by noting that I did define exactly what I meant by it.
As far as I can tell, we agree that if you don't want to exceed the
impact rating obtained for your half ropes by dropping a 55kg weight,
then you should try to avoid falls greater than fall factor 1 on a
single strand. This is my personal approach to using double ropes (I
rarely use anything else for climbs that are to be lead and followed
free), and I agree that this builds in a considerable margin of
safety. It is a conservative guideline that a leader stands a decent
chance of judging while in action, which is what I thought Julie was
asking for, and as you so clearly point out, failing to meet this
criterion is not automatically disasterous.
Before reading this thread, I thought the fall factor 1 guideline was
widely known if not accepted. When no one mentioned it, I started
looking around to see why I thought I knew this. I only found two
references, and they are hardly conclusive. One is in Mark Twight's
"Extreme Alpinism," Chapter 12, the section on Half Ropes, page 162:
"Any of these ropes can serve as a Single climbing rope if the fall
factor...will be less than 1. But if a serious fall is a possibility,
only using both will achieve an acceptable level of safety." The
other reference I found is in the Blue Water technical manual, which I
couldn't find on the Blue Water site. However, a copy is posted at
http://spelean.com.au/BW/TM/BWtechdyn.html. What it says is "Half
ropes...can be used as a single rope when the fall factor is less than
1. In the event of a serious fall, the necessary safety factors can
only be achieved when the rope is used double." These quotes may not
be about clipping one or two ropes at all, however, but rather about
circumstance in which it is acceptable to use a single half rope as
your only rope (for example, glacier travel, where the fall factor for
cravasse falls is 1.)
Richard
Julie
> As far as I can tell, we agree that if you don't want to exceed the
> impact rating obtained for your half ropes by dropping a 55kg weight,
> then you should try to avoid falls greater than fall factor 1 on a
> single strand. ...
> It is a conservative guideline that a leader stands a decent
> chance of judging while in action, which is what I thought Julie was
> asking for, and as you so clearly point out, failing to meet this
> criterion is not automatically disasterous.
Yes. Thanks much.
JSH
Guido
> As far as I can tell, we agree that...you should try
>to avoid falls greater than fall factor 1 on a
> single strand. This is my personal approach to using double ropes ...
> Before reading this thread, I thought the fall factor 1 guideline was
> widely known if not accepted.
> I only found two references, and they are hardly conclusive.
> One is in Mark Twight's "Extreme Alpinism," ...
> "Any of these ropes can serve as a Single climbing rope if the fall
> factor...will be less than 1. But if a serious fall is a possibility,
> only using both will achieve an acceptable level of safety." The
> other reference I found is in the Blue Water technical manual,..."Half
> ropes...can be used as a single rope when the fall factor is less than
> 1. In the event of a serious fall, the necessary safety factors can
> only be achieved when the rope is used double."
Great effort, Richard.
The question is begged then, how often do climbers, whilst crag or sport
climbing, willfully invade that zone beyond factor 1 falls?
My bet is that few readers waltz this zone with intentional frequency.
Factor one climbing is both an acceptable guideline, and a margin of safety
which most leaders oblige, if unknowingly, by common practice. Just do the
math.
Most leaders just need to respect, and pay particular attention to "short
rope situations" --- those "just off the belay" leads on steep rock where
surprisingly high impact falls may result from a leader fall on little rope
paid out.
Surprises happen in the short-rope zone, like hand, wrist, and thorassic
vertebrae injury to belayers. Add to that the potential for failure in the
highest nut placement, and/or the belay function itself, and a destiny
unforeseen looms like a lightning strike, as the anchors themselves pay the
ultimate price for misjudgement.
Has double rope technique fallen into disuse? Not with this climber.
Guido
"'Must be ten advantage to the use of double ropes. Can you list 'em?" ---
Old guide to his client over ales.