|
brunoschull
Dec 17, 2010, 10:55 PM
Post #1 of 22
(15748 views)
Shortcut
Registered: Nov 10, 2004
Posts: 47
|
Hi Folks,
Ice season...time to start thinking about V threads. I have built plenty of V threads for descending, anchors, and so on, but I always have the following question:
Anybody have any good ideas about how to join two V threads?
If I feel confident that the ice is good, I will trust one V thread, but if something doesn't feel right, I will always try to build a second. I go back and forth about equalizing independent loops of cord or webbing, one in each V thread, or using a huge amount of material to make one long loop passing through both V threads, pulled into a master point, and equalized like a cordalette.
Ideas?
Thanks,
Bruno
|
|
|
|
|
coastal_climber
Dec 17, 2010, 11:54 PM
Post #2 of 22
(15730 views)
Shortcut
Registered: Nov 17, 2006
Posts: 2542
|
You can do four holes, all pointing in and meeting, threaded together.
|
|
|
|
|
nh_ranger
Dec 20, 2010, 3:08 PM
Post #3 of 22
(15658 views)
Shortcut
Registered: Nov 8, 2005
Posts: 36
|
Another thing to keep in mind is how you orient the holes. I see most people doing threads with each hole horizontal of the other. This is a risky technique in hard, brittle ice considering that ice typically fractures horizontally, so in cold ice with horizontally placed threads, a crack could form between the threads, compromising the entire rig. Vertical v-threads, with one screw going down and the other going up is a better option. Also, the cord and dyneema sling trick is handy to know if you forget your coat hanger or don't want to shell out for the fancy-shmancy BD tool.
|
|
|
|
|
IsayAutumn
Dec 20, 2010, 5:24 PM
Post #4 of 22
(15607 views)
Shortcut
Registered: Oct 8, 2008
Posts: 355
|
nh_ranger wrote: Another thing to keep in mind is how you orient the holes. I see most people doing threads with each hole horizontal of the other. This is a risky technique in hard, brittle ice considering that ice typically fractures horizontally, so in cold ice with horizontally placed threads, a crack could form between the threads, compromising the entire rig. Vertical v-threads, with one screw going down and the other going up is a better option. Also, the cord and dyneema sling trick is handy to know if you forget your coat hanger or don't want to shell out for the fancy-shmancy BD tool.
What trick would that be?
|
|
|
|
|
charlie.elverson
Dec 20, 2010, 7:02 PM
Post #5 of 22
(15566 views)
Shortcut
Registered: May 12, 2009
Posts: 131
|
stick a dyneema runner through one hole so that the bight at the end is near where the holes meet. Then, push your cord through the other hole. If you do it right, the cord ends up in the loop formed by the runner and you can pull the cord through just like with a hanger (or a fancy schmancy BD tool)
|
|
|
|
|
rocknice2
Dec 20, 2010, 7:02 PM
Post #6 of 22
(15566 views)
Shortcut
Registered: Jul 13, 2006
Posts: 1221
|
IsayAutumn wrote: nh_ranger wrote: Another thing to keep in mind is how you orient the holes. I see most people doing threads with each hole horizontal of the other. This is a risky technique in hard, brittle ice considering that ice typically fractures horizontally, so in cold ice with horizontally placed threads, a crack could form between the threads, compromising the entire rig. Vertical v-threads, with one screw going down and the other going up is a better option. Also, the cord and dyneema sling trick is handy to know if you forget your coat hanger or don't want to shell out for the fancy-shmancy BD tool. What trick would that be?
Shove the sling into one hole then shove rope into the other. Pull out sling with the rope in tow. If your lucky.
I tried this and it does work but a tool is sooooo much easier. It helps to freeze the sling to help get it into the holes bottom. Then you need to get the rope into the loop of the sling.
Long story short do not forget your Abalakov tool
OP question
To minimize cord lenght when using 2 V-threads. Take 1 end of cord and thread through 1st V. Finish with fig8 follow thru. Do the same for other V. Make a master point with the single strand of cord between the two V-threads.
I hope that makes sense.
|
|
|
|
|
coastal_climber
Dec 20, 2010, 7:04 PM
Post #7 of 22
(15563 views)
Shortcut
Registered: Nov 17, 2006
Posts: 2542
|
IsayAutumn wrote: nh_ranger wrote: Another thing to keep in mind is how you orient the holes. I see most people doing threads with each hole horizontal of the other. This is a risky technique in hard, brittle ice considering that ice typically fractures horizontally, so in cold ice with horizontally placed threads, a crack could form between the threads, compromising the entire rig. Vertical v-threads, with one screw going down and the other going up is a better option. Also, the cord and dyneema sling trick is handy to know if you forget your coat hanger or don't want to shell out for the fancy-shmancy BD tool. What trick would that be?
what do you mean, trick?
|
|
|
|
|
juho.risku
Dec 21, 2010, 10:37 AM
Post #8 of 22
(15466 views)
Shortcut
Registered: Feb 11, 2009
Posts: 42
|
To equalize two V threads I would propably do following:
1. Do two V threads to atleast 20-40 cm distance of vertical height (measured from the nearest hole) and about the same in horizontal.
2. Use single long atleast accessory cord (about 3-4 times as long as typical one) and thread it through the first hole and using the same end also trough the second.
3. Use small and cheap steel connector / biner to balance the threads as you would balance a belay station built from two screws (i.e. clip the frist strand of the loop, turn the connector around and clip to the other strand). The connector should be rated around 10kN.
Leaving behind one cheap connector, propably worth less than $5, is not a big thing (you don't end up doing that too often anyways). The benefit of this approach is that this approach allows "real" balancing, i.e. the connector to move back and forth as the rope moves and more equal distribution of power than cordlette ever does + it requires less cord than the cordlette.
As I can imagine that my non native english left something unclear, feel free to ask... or critizise. :-)
Note: Ever tried this though. I've new had to equalize a V-thread... we usually test the thread having atleast one screw further away attached to the rope, and the heavier climber is used as a "test" (i.e. go first + give a good bang to the rope). :-)
|
|
|
|
|
walkonyourhands
Dec 21, 2010, 12:33 PM
Post #9 of 22
(15450 views)
Shortcut
Registered: Sep 7, 2004
Posts: 128
|
nh_ranger wrote: Another thing to keep in mind is how you orient the holes. I see most people doing threads with each hole horizontal of the other. This is a risky technique in hard, brittle ice considering that ice typically fractures horizontally, so in cold ice with horizontally placed threads, a crack could form between the threads, compromising the entire rig. Vertical v-threads, with one screw going down and the other going up is a better option. Also, the cord and dyneema sling trick is handy to know if you forget your coat hanger or don't want to shell out for the fancy-shmancy BD tool.
Can someone elaborate/confirm this? Never heard that before.
|
|
|
|
|
cfnubbler
Dec 21, 2010, 2:31 PM
Post #10 of 22
(15434 views)
Shortcut
Registered: Oct 31, 2003
Posts: 628
|
I read test data last year that indicated that all other things being equal, vertically oriented threads are stronger than the traditional horizontal configuration.
This does seem intuitive as well: We all try to avoid placing tools side by side because of the possibility of horizontal fracturing, right?
|
|
|
|
|
NandaDevi15
Dec 21, 2010, 7:50 PM
Post #11 of 22
(15408 views)
Shortcut
Registered: Apr 8, 2010
Posts: 6
|
Why not run one long piece of cord through both v-threads and equalize the to anchors at a mid point with a figure eight? Assuming you can anticipate the direction pull, which in a decent should be straight fairly forward.
|
|
|
|
|
juho.risku
Dec 21, 2010, 9:48 PM
Post #12 of 22
(15379 views)
Shortcut
Registered: Feb 11, 2009
Posts: 42
|
Ofcourse you can, I've just found out that an equalization that's "fluid" is more secure and it's easier to get the force distributed to both anchors more equally, and in it keeps equalized in all circumstances (even in cases of accidental movement of rope, which has happened few times for me in such places where the line of descent is not straight) + it's easier and more straight forward to do in "my way". But that's just my opinion.
Furthemore as said I've never tried such balancing with V-threads (always felt comfortable enough without), only with two screws and a sling + carabiners as a belay anchor...
|
|
|
|
|
NandaDevi15
Dec 22, 2010, 6:57 AM
Post #13 of 22
(15337 views)
Shortcut
Registered: Apr 8, 2010
Posts: 6
|
I see what you mean now, it would allow for a more fluid movement to take care of any play that may be in the anchor. I never had to set a double v-thread but am very interested in trying it out and getting a good method down. I've been in situations before where the ice was brittle enough that I set my anchors vertically to help avoid fracture and it would have been nice have a back up. For the connector that you mention would you use a locking carabiner or something like a steel quicklink or rappel ring?
|
|
|
|
|
juho.risku
Dec 22, 2010, 9:34 AM
Post #14 of 22
(15316 views)
Shortcut
Registered: Feb 11, 2009
Posts: 42
|
In terms of connector I guess anything strong enough with sufficient margin would be good enough. Lighter / simpler / more straight forward = better. I mean it's not a huge loss to lose an old locking carabiner, but a iron store steel loop with screw lock should do it as well as well as rappel ring. Later ones being propably a lot cheaper than carabiners.
This being said though there might be some importance in how thick the material of the loop is, as the force is applied to wider surface at the point where connector touches the cord. I'm also not sure if flat / tubular tape would be better than cord, due it's shape, and how would that affect to the freedom of movement + strength. I guess I have to try it as well. :-) Luckily there's some time soon, I'll try it + post some photos to my blog about it.
|
|
|
|
|
brokesomeribs
Dec 22, 2010, 4:34 PM
Post #15 of 22
(15277 views)
Shortcut
Registered: Jul 20, 2009
Posts: 361
|
walkonyourhands wrote: nh_ranger wrote: Another thing to keep in mind is how you orient the holes. I see most people doing threads with each hole horizontal of the other. This is a risky technique in hard, brittle ice considering that ice typically fractures horizontally, so in cold ice with horizontally placed threads, a crack could form between the threads, compromising the entire rig. Vertical v-threads, with one screw going down and the other going up is a better option. Also, the cord and dyneema sling trick is handy to know if you forget your coat hanger or don't want to shell out for the fancy-shmancy BD tool. Can someone elaborate/confirm this? Never heard that before.
This was first (I think) published in Luebben's "How To Climb Ice" book. Results of his thread testing were: Ice tends to fracture horizontally and A-threads (vertical orientation) are much stronger than V-threads (horizontal orientation). V-threads are certainly strong enough. I don't recall ever hearing a single instance of a failed V-thread. It's just that A-threads are stronger, maybe by 30%-40% if I remember correctly.
It's possible that someone else did the original research and I would love to give them the proper credit, but I can't recall seeing it anywhere earlier than Luebben's book which was published in the '90s.
There have been a couple suggestions here for methods to equalize the slings. One guy suggested tying 2 individual threads, and then equalizing with another loop of cord. This is the cheapest way to do it, but it scares the shit out of me. That's a LOT of cord-on-cord connections. Something starts slipping and you have 5 different points where friction could melt something and then you die. That's why I like Juho's method... it's the best, but also the most expensive.
I would reserve it for only the very worst ice. I use regular hardware store stainless steel quicklinks AKA maillons that are rated to 1200 lbs. Some folks here like to insist on Petzl maillons which cost 4x as much. Even though I'm positive that they are right and the Petzl ones are stronger and have better quality control, I'm not that concerned. 1200 lbs is more than enough margin of safety for me when on rappel. One time I added a loop of backup cord just in case cause I was using a maillon I found in the snow the previous season. It held fine and the cord was never needed in the end. Oh well.
One thing I want to point out: there is no "fluid" anything (aka ""dynamic equaliztion") with that method. It is not like using a sliding-X at all. You only get the benefits of dynamic equalization when the loop is a single closed loop like a sewn runner; when you have 2 separately tied threads, their length is fixed so a non-vertical rappel will still load them unequally. But as Juho correctly guessed, using flat 1" webbing will certainly bind more than using regular 6mm cord. Cord is obviously the better choice in this scenario.
With regards to strongest construction, I would build 2 A-threads side by side, at least 18 inches (45cm) apart, with one set of threads higher than the other also by 18 inches (45cm) or more. Make sure you have enough cord so the loops from each thread hang down to the same level. In good ice, this configuration would probably be able to lift up a truck. In shitty ice.... hopefully strong enough to hold you and your partner. :)
Something to keep in mind... ice is amazingly strong. Watch this video from Arc'Teryx on building threads: http://vimeo.com/7856042. The magic is at the end of the movie where you see how little ice can support 3 big men. The point I'm trying to make: If the ice is so bad that you need 2 threads, use a quicklink/maillon/bail biner to join them so you get the benefits of no cord-on-cord friction like I mentioned before.
|
|
|
|
|
juho.risku
Dec 23, 2010, 12:19 AM
Post #16 of 22
(15202 views)
Shortcut
Registered: Feb 11, 2009
Posts: 42
|
I just want to point out, thay setting I suggested involves a single loop (that's going through both V-threads) with only one knot... i.e. no two separately tied threads --> as close to sliding X (if I got it correctly what you ment) as I could think of, while using V-thread. --> That's the reason why I suggested it. --> Use single piece of cord / flat / tubular tape, thread it through both V-threads and equalize it as you would with sewn sling with two screws = as close as possible to same as swen sling, without having a sewn sling but tied knot.
Dont' know if this clarification was necessary... I just mean that I THINK that "fluid" / "dynamic" equalization with a V-thread is possible.
|
|
|
|
|
juho.risku
Dec 30, 2010, 5:42 PM
Post #17 of 22
(15020 views)
Shortcut
Registered: Feb 11, 2009
Posts: 42
|
Tested balanced V-thread with 7mm accessory cord, and old carabiner in "sliding-X" type of setting. The balancing works just fine and accessory cord alings fine within the carabiner as well. Will post few images of our "setup" on my blog next week once I'll get somewhere with better network connections.
|
|
|
|
|
rocknice2
Dec 30, 2010, 10:04 PM
Post #18 of 22
(14973 views)
Shortcut
Registered: Jul 13, 2006
Posts: 1221
|
juho.risku wrote: Tested balanced V-thread with 7mm accessory cord, and old carabiner in "sliding-X" type of setting. The balancing works just fine and accessory cord alings fine within the carabiner as well. Will post few images of our "setup" on my blog next week once I'll get somewhere with better network connections.
Thanks for taking the time to do a test.
IMO it's kind of a moot point. sorry.
I have no problem leaving quick links or 'biners on rockclimbs but on ice it's just piece of cordelette. I rarely make double V's. 1 good one is plenty.
I just find it a big waste for something that will only be around for a few months.
If it's a tree atop a clmb then I will leave a quick link.
|
|
|
|
|
juho.risku
Jan 2, 2011, 5:38 PM
Post #19 of 22
(14892 views)
Shortcut
Registered: Feb 11, 2009
Posts: 42
|
Agree. :-) I've never needed double V-thread in real situation so far... just being curious. :-)
|
|
|
|
|
rocknice2
Jan 4, 2011, 12:44 AM
Post #21 of 22
(14824 views)
Shortcut
Registered: Jul 13, 2006
Posts: 1221
|
A great example when to equalize an anchor.
or
Don't place screws on bulges and into new ice columns
|
|
|
|
|
juho.risku
Jan 4, 2011, 9:08 AM
Post #22 of 22
(14787 views)
Shortcut
Registered: Feb 11, 2009
Posts: 42
|
I know, it's not an great example. It's just a demo of equalization. There are several other problem areas too, including the fractured ice between the screws, long fracture line (because as you pointed out it's on bulge), too shallow holes, the knot in sliding X is too far, I didn't match the length of cord excactly to the need etc. ... I've commented some of them on image headings.
The spot was selected because it was easy, especially from the photography point of view. It's on top of the Brown River which allows the descent without abalakov anyways (lots of trees + only single pitch).
|
|
|
|
|
|
