gri-gri as anchor for top belay?

Lost gear? Selling? Donating? Questions?

Moderators: chossmonkey, Dom, granite_grrl

gri-gri as anchor for top belay?

Postby tracstarr » Sat Jul 16, 2005 6:23 pm

just wondering opinions on using a gri-gri as the main anchor point for top belay. saw a lot of it in acadia national park this weekend.
User avatar
tracstarr
 
Posts: 495
Joined: Wed Oct 27, 2004 7:26 am
Location: at my desk

I miss bah habbah

Postby mathieu » Sat Jul 16, 2005 6:56 pm

I use my reverso as a top belay, don't really see the difference. If you have a bomber anchor why put your back out holding some person struggling up a climb when the anchor can do the work for you. As long as the anchor is properly built I can't see the problem. You trust your anchor, right?!?
mathieu
 
Posts: 412
Joined: Wed Oct 20, 2004 12:56 am
Location: Alberta

Postby tracstarr » Sat Jul 16, 2005 9:38 pm

for sure i trust it :) just haven't seen it done that way before. I suppose i've used the reverso the same way too. i actually kinda like it better for situations you have to TR from the top like at acadia this weekend. Just sometimes it's hard to watch the climber unless you setup your anchor over the edge for yourself too.

I guess i'm use to setting 2 locking at the anchor point and not relying on just the one. I mean for TR one should be enough, but is 2 a better idea? I mean i've seen people go off one anchor, me, I like 3, redundancy is a good thing in climbing. So i guess that poses the question.... how would you backup the gri-gri if it's the anchor?
User avatar
tracstarr
 
Posts: 495
Joined: Wed Oct 27, 2004 7:26 am
Location: at my desk

Postby mathieu » Sat Jul 16, 2005 11:39 pm

I think its probably unrealistic to expect to back up a gri gri used as a TR Anchor. I think there was a post about this a month ago but things seem hard to find cause post seem to deviate from the original subject pretty quickly.

The scenario where I put 2 biners at the top of a TR is that usually you aren't there to physically inspect it. To each there own comfort level AND again its situation dependant. If I set up a gear anchor for a climb that's gonna be climbed all day by beginners then its a 4 piece. If its a multipitch climb and I sink in 2 bomber pieces and one questionable one, I'm happier than a pig in flowers. Its the 3 flowery piece anchor where one is a #4 nut that scare me.

A past experience just flashed in my head. Lesson learned was that if your gonna use 2 biners for a TR anchor make sure that your slings leading from your anchor to the 2 biners is redundant. This is especiallytrue if you need to extend the anchor over an edge such as in Otter cliff in Bah Habbah. Buddy had his anchor all redundant and perfect then used one long sling to reach over the edge and then slapped 2 lockers. Last I checked, nylon slings don't slide smoothly over a sharp granite edge.

Here's something to keep you awake at night, did you know that steping over a rope with crampons is proven not to be as dangerous as climbing with a wet rope. They did tests (UIAA) and it showed that a wet rope would lose more of its strenght than a rope that was stepped on with crampons. We are talking stepping here not jumping on the rope, hence the rope fibers don't actually get severed they just get squished. I should look for that article on the web but i'm too lazy and I am gonna rely on heresay.

CHeerio
mathieu
 
Posts: 412
Joined: Wed Oct 20, 2004 12:56 am
Location: Alberta

Postby Fred » Sun Jul 17, 2005 9:48 pm

belaying from the top with a gri-gri is the way to go. I usualy clip it directly to my harness though and use a short TR directional to my anchor. The gri gri only gives me the added security when I'm fiddling with the rope on a small ledge or hanging belay. Although the reverso is nice because it's autolocking, once it's loaded you can't remove the load without assistance from the climber. So if your second isn't a strong climber and they fall in mid air trying to pass a roof you'll be cursing. This can also pose some problems in a rescue situation. With the grigri however, you can simply pull back the lever.

One thing to be carefull of if you clip your grigri directly to the anchor is to have the caming mechanism pulling out from the cliff. You don't wan't the caming action being restricted by the wall. Yikes!
I want to go to hell... there's probably lots of rock to climb there.
User avatar
Fred
Site Admin
 
Posts: 3140
Joined: Wed Oct 20, 2004 12:30 am
Location: Fredericton, NB

Postby dcentral » Sun Jul 17, 2005 10:20 pm

Beyond Gravity belays off the floor. It's pretty much the same thing just in reverse.
User avatar
dcentral
 
Posts: 653
Joined: Wed Oct 27, 2004 10:00 pm
Location: Victoria, BC

Postby The Teth » Mon Jul 18, 2005 12:09 pm

Just a thought here, if you wanted to back up a GriGri from an anchor standpoint you could alway clip a carabineer to the rope on the climber side of the GriGri and have it setup on a separate anchor. Since the GriGri will not fit through a carabineer that will act as backup if the anchor the GriGri is on fails. It also should not get in the way too much. If the GriGri fails, rather than the GriGri’s anchor, you are out of luck though.

Back when I was a newbe my belay partner setup a top belay off his harness and anchored his harness to a tree about 10 feet away using dynamic rope. He also left the anchor a bit on the loos side. A flake pealed off when I was about 15 feet off the ground. The result was that my toe touched dirt at full rope stretch before I bounced back, and my belay partner ended up dangling upside down about three feet from the top of the cliff. And that is how you take a 15 foot fall on top-rope. Ironically I have never fallen more than a couple of feet on lead.

Teth
User avatar
The Teth
 
Posts: 453
Joined: Wed Oct 27, 2004 1:01 pm
Location: Halifax

Postby PaulB » Mon Jul 18, 2005 2:49 pm

Fred wrote:Although the reverso is nice because it's autolocking, once it's loaded you can't remove the load without assistance from the climber.

There is a technique for doing this without assistance from the second. Put a sling through the autolocking biner and run it through a biner which is above it in the anchor. Weight the sling (using a foot works well) and the mechanical advantage of the sling will unload the autolocking biner.

There's a picture of this on the Petzl website, but I can't give a direct link to it. Work through the menus (Technique/Mountaineering/Rescue) and you'll find it.
PaulB
 
Posts: 107
Joined: Thu Oct 28, 2004 12:46 pm
Location: North Vancouver, BC

In theory Marge, communism would work, IN THEORY.

Postby mathieu » Mon Jul 18, 2005 8:06 pm

Every time I put someone on top belay with my reverso I always keep an eye out for setting up what you just described. ALthought it seems good in theory, I heard that in practice its actually hard to free the device. Chris H tried it with a rather large sherpa tied to the other end (free hangin) and said it was nearly impossible, basically your foot needs to press down close to the person's weight. Chris said that he was jumpin on the sling and the sherpa didn't move. I wouldn't recommend using the reverso on any climb that you think your partner may A) not be able to second or B) Have a nasty traverse where pealing off would result in a free hangin situation. I guess it would be good practice to review your rock rescue skills :wink: .

Mathieu
mathieu
 
Posts: 412
Joined: Wed Oct 20, 2004 12:56 am
Location: Alberta

Postby The Mitt » Mon Jul 18, 2005 9:10 pm

I guess thats why having a few slings or ready made prusiks are a good thing to have on hand. That way the second could use a klimhiest (sp) or prusik to get to the belayer.

Mitt
User avatar
The Mitt
 
Posts: 847
Joined: Sun Dec 12, 2004 5:22 pm
Location: Prospect NS

Postby Fred » Tue Jul 19, 2005 7:59 am

PaulB wrote:
Fred wrote:Although the reverso is nice because it's autolocking, once it's loaded you can't remove the load without assistance from the climber.

There is a technique for doing this without assistance from the second. Put a sling through the autolocking biner and run it through a biner which is above it in the anchor. Weight the sling (using a foot works well) and the mechanical advantage of the sling will unload the autolocking biner.

There's a picture of this on the Petzl website, but I can't give a direct link to it. Work through the menus (Technique/Mountaineering/Rescue) and you'll find it.


yeah I've heard of that but I also heard it's impossible to do. I was looking at getting a reverso once but this problem sorta turned me off the idea. I guess I should try it so I can see it for myself though. :)
I want to go to hell... there's probably lots of rock to climb there.
User avatar
Fred
Site Admin
 
Posts: 3140
Joined: Wed Oct 20, 2004 12:30 am
Location: Fredericton, NB

Postby PaulB » Tue Jul 19, 2005 1:01 pm

How well it would work would definitely depend on many factors (the weight of the second, the angle of the terrain, the leverage that the belayer can generate on the sling, etc), but it's simple to set up, so it's at least worth trying. If it doesn't work, you'd need to use some simple rock rescue systems for transfering loads & doing a z-haul to get things sorted out. Interesting things to experiment with on rainy days.
PaulB
 
Posts: 107
Joined: Thu Oct 28, 2004 12:46 pm
Location: North Vancouver, BC

gri gri on the anchor

Postby john » Mon Aug 15, 2005 8:23 am

I normally don't bother with these discussions but this one interested me for many reasons. A few corrections so misinformation doesn't multiply.

1) dcentral:

A gri gri on the floor is not the same as directly off the anchor, since at BG it is attached at the floor then goes up to the roof, allowing rope stretch and force dissapation (25ft?) in the event of a TR fall and is then redirected by a biner and more dymanic rope to the climber. Directly off the anchor a gri gri and reverso are both considered a static belay due to their minimal slippage, therefore translating all the fall force minus the rope stretch to the anchor. This is not a problem top roping due to the minimal forces involved assuming you have a safe anchor. Where this can make a difference is in a situation where there might be some accidental slack in your belay, typical if you are standing on a ledge not hanging on the belay. Even slight slack in a static belay, ie. any dynema slings coupled with a static belay device, greatly increases anchor forces even in a small fall (See rock and Ice a few months back for the numbers). So make sure there is no slack at all, and your anchor is safe, if it is queationable and you still want to use a gri gri, put it on your waist and redirect it through the power point with a biner so your body can absorb some of the fall force. If I misunderstood your point sorry.

2) A reverso can be unloaded failrly easily with a bit of practice in almost any situation. As stated it is slightly dependent on the belayers strength vs the climber weight and drag ect. but, mostly dependent on the unloading technique. Here are a few tips that may help when uses in the autoblocking mode.

If the fallen climber is light often even without their help if you pull up on the climbing strand and take the autoblocking biner in your other hand and twist it perendicular to the rope while giving a tug towards the upwards direction along the same path as the fallen climber I have found I can easily unweight the rope, the key is the slight twist to initially unload the camming action.

Secondly as mentioned attaching a sling to the locked biner then standing on it does work although providing a jerkey descent. I have used this to lower much heavier people than myself out over overhangs and on at least 2 occasions.

Third for the fatest of climbers you will need a little trick I have been experimenting with. (Disclaimer use only with solid individual anchor points.) clip the long slind to the locked biner like above, but then clip a biner or quickdraw to a single anchor point well above the reverso. Pass the sling up through the biner and then down to your foot. Then step on that. The reason this works seems to be due to the direction of the forces involved. A loaded reverso pulls the lock biner into the reverso with a slight angle with respect to the diretion of the rope to the fallen climber. By stepping in a sling attached direcctly to this biner it is bending the rope more and if you are not careful it just tightens down on the rope. So either really pay attention to the direction you step with your foot, straight down is not the best or try the redirection. I haven't used this method much, but I thought I would mention it for interest.

cheers
john
 
Posts: 314
Joined: Tue Nov 16, 2004 11:08 am
Location: Fred. NB

Postby Fred » Mon Aug 15, 2005 9:56 am

I disagree slightly.

If you yourself are belaying from the top and "not weighting" the anchor but the gri-gri is attached to anchor directly... there will be less force to the anchor then if you send it from your belt then up to the anchor and back. Here's why...

There may be more static force due to the way the mechanism absorbs the load but the rope is still dynamic. This only becomes close to static as the climber approaches the anchor (i.e. short rope) From a top belay you'll get this regardless of if you belay from the anchor or your belt. The only difference from your belt would be that your weight can come up and give a softer catch but this is true anywhere on the climb.

When you belay from your belt you will absorb some load because your body weight will lift a little and absorb some of the load but here's the kicker. With that set-up you have the weight of two people on the anchor. If the gri-gri is directly on the anchor and the belayer is standing freely on the ledge then only the weight of one climber goes to the anchor with a slightly higher impact force (depends on the amount of rope out).

I'm talking about 90% of the cases where the belayer is pretty much standing on a ledge to belay up the second thus not really weighting the anchor. I suspect the weight of two climbers with a slightly more dynamic belay is probably more load than one climber on a slightly more static load to the anchor. Again, like John said, keep the rope tight and you won't have a problem with that.
I want to go to hell... there's probably lots of rock to climb there.
User avatar
Fred
Site Admin
 
Posts: 3140
Joined: Wed Oct 20, 2004 12:30 am
Location: Fredericton, NB

rebuttle

Postby john » Tue Aug 16, 2005 7:51 am

I have read that argument before and will post my rebuttle as soon as I find the link, interesting thoughts though. I think I have seen a similar test to this effect on RC.com. I'll look
john
 
Posts: 314
Joined: Tue Nov 16, 2004 11:08 am
Location: Fred. NB


Return to Gear

Who is online

Users browsing this forum: No registered users and 2 guests

cron