|
ARMClimbing
Apr 20, 2013, 5:13 PM
Post #1 of 15
(11383 views)
Shortcut
Registered: Dec 1, 2012
Posts: 2
|
The most comon top rope set up when you have two bolts, either parallel o one higher than the other is to pass through some webbing, make a loop and then tie an overhand in the direction of the pull. My question is that if it would be ok to do the following: I have alot of old rope. I would take a 3 or 4 ft peace of old rope and tie double overhands to each extremity for bolt conection and then use a clove hitch with two opposing biners in the direction of the pull. Strength and security wise, would this be ok?
|
|
Attachments:
|
homemade sport anchor.jpg
(148 KB)
|
|
|
|
|
shockabuku
Apr 20, 2013, 5:31 PM
Post #2 of 15
(11373 views)
Shortcut
Registered: May 20, 2006
Posts: 4868
|
ARMClimbing wrote: The most comon top rope set up when you have two bolts, either parallel o one higher than the other is to pass through some webbing, make a loop and then tie an overhand in the direction of the pull. My question is that if it would be ok to do the following: I have alot of old rope. I would take a 3 or 4 ft peace of old rope and tie double overhands to each extremity for bolt conection and then use a clove hitch with two opposing biners in the direction of the pull. Strength and security wise, would this be ok? 
Do you drive on tires with no tread?
Would it be okay, in a pinch, - probably - but I wouldn't use it and I probably wouldn't climb with someone who did.
Figure eight or the overhand would be a better choice in all locations, especially if you're going to use it repeatedly. If you have a lot of old rope, don't be cheap with it.
(This post was edited by shockabuku on Apr 20, 2013, 5:32 PM)
|
|
|
|
|
ARMClimbing
Apr 20, 2013, 6:01 PM
Post #3 of 15
(11357 views)
Shortcut
Registered: Dec 1, 2012
Posts: 2
|
Do you have a good reason why this is not valid?
double overhand is being used for much more important aplications (like rescue operations) and it is said to be very similar to the 8 knot in pull tests. The clove hitch works well even when it is pulled from one end so the individuality of the points is maintained. Could you explain your opinion with facts?
|
|
|
|
|
shockabuku
Apr 20, 2013, 6:25 PM
Post #4 of 15
(11347 views)
Shortcut
Registered: May 20, 2006
Posts: 4868
|
Not fully. It's unknown for use in this application (by me), and in the absence of a pretty good reason to use something unknown in place of something with demonstrated and known effectiveness - when my life is at stake - I'll stick with something I know. I also suspect the double overhand of loosening under cyclic loading.
Is there a good reason not to use the other?
|
|
|
|
|
csproul
Apr 20, 2013, 7:23 PM
Post #5 of 15
(11328 views)
Shortcut
Registered: Jun 4, 2004
Posts: 1769
|
Probably fine. I can't quite tell what the knot is at each bolt end, but an overhand or 8 on a bight would do just fine. But if it's a sport anchor, what's wrong with 2 quickdraws?
|
|
|
|
|
potreroed
Apr 20, 2013, 7:28 PM
Post #6 of 15
(11325 views)
Shortcut
Registered: Sep 30, 2001
Posts: 1454
|
Keep it simple. You have two bolts there already, just use two quickdraws.
|
|
|
|
|
acorneau
Apr 20, 2013, 7:49 PM
Post #7 of 15
(11320 views)
Shortcut
Registered: Feb 6, 2008
Posts: 2889
|
shockabuku wrote: Not fully. It's unknown for use in this application (by me), and in the absence of a pretty good reason to use something unknown in place of something with demonstrated and known effectiveness - when my life is at stake - I'll stick with something I know. I also suspect the double overhand of loosening under cyclic loading. Is there a good reason not to use the other?
FYI: A clove hitch as "master point" is common for some climbers and/or in some areas. I use it frequently.
The double-overhand (a.k.a. barrel) knot is widely used in the rescue and industrial rope access worlds. It will cinch down on the carabiner to hold it tight and there is no cyclical loading issues like a water knot in webbing.
I don't see any major problems with this rig, assuming the barrel knots have been pre-tightened with adequate tails.
|
|
|
|
|
shockabuku
Apr 20, 2013, 11:25 PM
Post #8 of 15
(11244 views)
Shortcut
Registered: May 20, 2006
Posts: 4868
|
acorneau wrote: FYI: A clove hitch as "master point" is common ...I use it frequently.
Why?
|
|
|
|
|
Winemaker
Apr 21, 2013, 1:16 AM
Post #9 of 15
(11210 views)
Shortcut
Registered: Apr 6, 2013
Posts: 15
|
I'm a newbie, so be easy on me but........ a couple of things jump out at me. First, the load won't be equalized because of the hitch, so a single rope/anchor only will be loaded. Second, if the rope breaks at the hitch the anchor will fail. A runner through both hardware biners with a twist will at least equalize load and save your ass if an anchor point fails.
(This post was edited by Winemaker on Apr 21, 2013, 1:17 AM)
|
|
|
|
|
acorneau
Apr 21, 2013, 2:09 AM
Post #10 of 15
(11188 views)
Shortcut
Registered: Feb 6, 2008
Posts: 2889
|
shockabuku wrote: acorneau wrote: FYI: A clove hitch as "master point" is common ...I use it frequently. Why?
When I create rope-based anchors (frequently on trad/multi-pitch routes) I use a clove as a master point. It allows me to easily adjust the master point to the "sweet spot" after the rest of the anchor has been constructed. Doing that with a fig-8 master point would be laborious and time consuming.
Secondly, if one side of the anchor gets more weight than the other unexpectedly (misjudged direction of pull) the clove hitch will cinch down in that direction thus allowing for better equalization between the two sides even after the fact.
Thirdly, the clove hitch takes much less material to tie than a fig-8 or overhand on a bight.
|
|
|
|
|
bearbreeder
Apr 21, 2013, 3:04 AM
Post #11 of 15
(11170 views)
Shortcut
Registered: Feb 2, 2009
Posts: 1960
|
its fine ... you wont die
|
|
|
|
|
wivanoff
Apr 21, 2013, 1:40 PM
Post #12 of 15
(11108 views)
Shortcut
Registered: May 23, 2007
Posts: 144
|
Winemaker wrote: I'm a newbie, so be easy on me but........ a couple of things jump out at me. First, the load won't be equalized because of the hitch, so a single rope/anchor only will be loaded.
True, it won't be 50/50. But it can be "distributed" or "shared" by easily adjusting the location of the clove hitch. Let's keep in mind that the anchor shown is made out of two bolts and a length of climbing rope. The same diameter climbing rope that you tie into your harness with a single loop. And people regularly take leader falls on gear that is a lot smaller than that top rope anchor.
Winemaker wrote: Second, if the rope breaks at the hitch the anchor will fail.
See my comments about the anchor being made out of a length of climbing rope. Look here http://www.geir.com/mythbuster.html and scroll down to Myth #4
Winemaker wrote: A runner through both hardware biners with a twist will at least equalize load and save your ass if an anchor point fails.
Using your argument, you're concerned about one leg of the climbing rope anchor breaking. What happens if one leg of your twisted sling (magic X) breaks? Unless you've tired limiter knots, your screwed.
In short, while it might not be my first choice to build an anchor as shown, it's fine. I'd probably use one runner on each bolt and join them at the masterpoint. I see no reason to carry a length of climbing rope specifically to build the anchor shown - especially when I already have slings with me anyways.
Winemaker, for a while I too bought into the "[dynamically] equalized and no extension" bullcrap with all types of nerd-o-lettes. I now believe that "distributed as best as you can" and "NO extension" is a better anchor solution. But then, see my signature....
|
|
|
|
|
qwert
Apr 22, 2013, 8:12 AM
Post #13 of 15
(10937 views)
Shortcut
Registered: Mar 24, 2004
Posts: 2394
|
ARMClimbing wrote: I would take a 3 or 4 ft peace of old rope and tie double overhands to each extremity for bolt conection and then use a clove hitch with two opposing biners in the direction of the pull. Strength and security wise, would this be ok?
The clove hitch: How does it behave with two biners? I could imagine that the possible movement of the biners against each other might cause some slippage/ prevent the clove from coming thight.
I'd just use a normal overhand for every pictured knot, and if I need some adjusting, I'd place cloves at the legs.
If you have some rope, and you need/want a dedicated toprope anchor that seems like an easy and cheap solution, but on the other hand, why would you need/want a dedicated toprape anchor…
qwert
|
|
|
|
|
qwert
Apr 22, 2013, 8:16 AM
Post #14 of 15
(10935 views)
Shortcut
Registered: Mar 24, 2004
Posts: 2394
|
Winemaker wrote: I'm a newbie, so be easy on me but........ a couple of things jump out at me. First, the load won't be equalized because of the hitch, so a single rope/anchor only will be loaded. Second, if the rope breaks at the hitch the anchor will fail. A runner through both hardware biners with a twist will at least equalize load and save your ass if an anchor point fails.
I wont go into the details, but the current result seems to be that dynamic equalization does not work, and in those situation where you would need it the most, trying to go for it might actually be detrimental.
But in the case of a sport anchor with two solid bolts, it does not matter. If you manage to put a load on your anchor that is that big that you need to distribute it in order for the bolts to hold, you are doing something very very very wrong anyways.
qwert
|
|
|
|
|
Libbster
Apr 22, 2013, 3:08 PM
Post #15 of 15
(10865 views)
Shortcut
Registered: Oct 16, 2012
Posts: 48
|
Two quickdraws are fine when the bolts are right against the wall like in the picture. However if there is a ledge quickdraws are not good enough because you need to extend the masterpoint. I would still use some webbing and two locking biners anyway. I prefer a locked masterpoint
|
|
|
|
|
|
