Giga Jul Initial Impressions

Sorry to still disagree but I don't think the Munter allows "controlled" slippage. It just slips, same way as an ATC.
The idea that one could grip with more or less strength to let more or less rope slip is appealing but not realistic.
The Munter (or Tube) will just slip at lower loads for a weaker / lighter person and at higher loads for a heavier / stronger or more experienced belayer.

Fran M wrote: Sorry to still disagree but I don't think the Munter allows "controlled" slippage. It just slips, same way as an ATC.
The idea that one could grip with more or less strength to let more or less rope slip is appealing but not realistic.
The Munter (or Tube) will just slip at lower loads for a weaker / lighter person and at higher loads for a heavier / stronger or more experienced belayer.

You've obviously never seen a good competition belayer using a fast 8 or similar. Or learnt to belay 40 years ago.

as for testing: i don't think a single test is going to definitively prove much. not even several.....i get the outlier event, but let's imagine Test X results in a completely severed rope and we all take that as conclusive. What if, though, tests 2-10 all resulted in a glazed rope, but nothing more severe? So, do we go with the single severe test or the 9/10 tests? Maybe it's my utterly horrific sense of stats/math/etc.....but a single test about much of anything doesn't seem convincing....reproducible results in large-batch testing seems like you can draw conclusions from it.....but maybe I'm being dense (likely).

The problems with your example is are two-fold. First someone had to decide what the acceptable failure rate is, 1 in 10 times the rope fails or 1 in 1000000? Then if the variability in the results is random there is no reason why the first 900000 tests aren't "good" and the next 10000 "bad". It's still a 1 in 10 occurance but you would never detect it. So we look to eliminate the random factors and so are back to only needing a limited number of tests, often one is enough.

Jim Titt wrote:

You've obviously never seen a good competition belayer using a fast 8 or similar. Or learnt to belay 40 years ago.

Certainly havent. But I am referring to the fixed-point belay in a multi pitch setting. Do you think it's possible in such case?

Fran M wrote:

Certainly havent. But I am referring to the fixed-point belay in a multi pitch setting. Do you think it's possible in such case?

Sure.

coppolillo wrote: Oh, and rich...recall that lowered peak forces in the ensa testing was allowing the rope to run thru the Munter a bit/slippage, not sure if they’d get the same result if somebody gave a hard catch w the Munter...they call it out as an “expert” technique...

Looking closely at the video is appears that the rope slippage was similar between the harness belay and the fixed point belay.

I think the ultimate high load for the harness belay vs. the fixed point belay had more to do with

• little friction in the system.  I don't know what the top carabiner was but a DMM revolver would probably maximise the differential in two belay method.
• accelerating the mass of the belayer
• stopping both the faller and the belayer simultaneously. 

More friction in the system while accelerating the belaying would reduce the energy in the system when the belayer is ultimately stopped.  Having an even longer tether would allow the friction in the system more time to dissipate energy and also reducing the ultimate impact force.

climber pat wrote:

I don't mean to be rude, but I do feel it important to put forth really good information if at all possible and I had asked about the rope previous to my reply.  In any case I am happy that you are willing to clarify what happened.

I still am unable to determine if you had several drops on the same section of rope before the sheath was damaged and core exposed of just one drop on a used rope.  If more than one drop do you have any idea how many?  What other devices where used in previous drops?  Where the knots untied and retied?  What brand/model of rope was used?  Was this somebody's rope who was willing to donate it to the cause because it was worn out or did Petzl pony up a new rope?  It is easy to imagine a test scenario which would give a very bad and potentially false impression of the giga jul.  For example test 3 times on a ATC, the 3 times on a muntner, then start testing with the giga jul with 6 fall factor 2 falls already on the section of rope.

In summary:

1. Was the rope new?
2. What brand/model rope?
3. If the rope was previously used, how much use?  (days climbing, very fuzzy, ready for retirement, looked good,...)
4. Was a different section of rope used for each device?
5. If the same section was used for multiple devices which devices were tested before the giga jul and how many drops for each device.
6. If a new section was used for the giga jul how many test falls before it failed.
7. Were the the giga jul and ohm tested 1st therefor being tested on the ends of a used rope?
8. It appears the fall length was about 10 feet (twice the fall from the anchor at a leaders shins)?

I have never even seen a giga jul so I don't have any real knowledge about it.  I ordered one today so I can play with one and form my own impression.  I have both the micro and mega jul but I thought both were finicky and gave up using them after looking at Jim Tritt's graphs on their holding power.

I had seen the 1st and 3rd video you linked above and find the technique intriguing especially using a munter hitch to belay.   I prototyped the ATC version of the fixed point belay a couple of years ago and was not very satisfied with it and have not tried it in a real climbing situation.

I have been working on building my own drop tower to test this and other scenarios that seem under evaluated or not even addressed by most UIAA/CE or vendor testing.  I have the measurement electronics and release mechanism worked out; I still need to get a winch to lift the weight and actually build the tower.  I have been testing by dropping small weights off of a ladder.  My long term plan is to make this an open source tower in the sense that I will, for free, drop stuff for people who supply the items to be tested.  I will document the process and measurements for free as long at the documentation and measurements are available to anyone wanting to look at it.  

So many questions, so little data.

If you are going to study belaying make the tower high, 20m seems to be the usual useful height and the CAI also use a 50m high cliff. Mine could do 25m falls with 50m of rope out but it's getting complicated by then. You also want a controlled belayer hand force for some stuff, there are a couple of designs in general use.

Jim Titt wrote:

Sure.

Just to be clear, FF1 fall at the Padova tower (MCAI): https://youtu.be/tYZ4Hg92yXM

Controlling slippage there? I'd buy you a whole cradle and then some.

Jim Titt wrote:

If you are going to study belaying make the tower high, 20m seems to be the usual useful height and the CAI also use a 50m high cliff. Mine could do 25m falls with 50m of rope out but it's getting complicated by then. You also want a controlled belayer hand force for some stuff, there are a couple of designs in general use.

Thanks for the input.  I will give it serious consideration.  I was thinking about 10 meters.  I am very interested in testing belay devices and also controlled breaking of protection (simulating a piece pulling and the load falling onto the next piece).

In another thread you already explained to me why my initial thoughts on a controlled belay hand were terribly wrong.  I will look into what I can find that others are doing.  My current thought is a clamp calibrated to some level but that seems unlikely to be as repeatable as i would like.  Another idea floating around in my mind is a wheel connect to a motor controlled by a computer monitoring a speed sensor and strain gauge.  I worry about the response time of this design.  If you have a reference to a good design i would love to look at it. 

climber pat wrote:

Thanks for the input.  I will give it serious consideration.  I was thinking about 10 meters.  I am very interested in testing belay devices and also controlled breaking of protection (simulating a piece pulling and the load falling onto the next piece).

In another thread you already explained to me why my initial thoughts on a controlled belay hand were terribly wrong.  I will look into what I can find that others are doing.  My current thought is a clamp calibrated to some level but that seems unlikely to be as repeatable as i would like.  Another idea floating around in my mind is a wheel connect to a motor controlled by a computer monitoring a speed sensor and strain gauge.  I worry about the response time of this design.  If you have a reference to a good design i would love to look at it. 

Pretty sure when Beverley et al did their sequential failure tests the tower was higher but you could look and see.  The DAV "hand" is two steel plates clamped together by springs and they adjust the preload on them. The whole thing on a strain guage obviously. The CAI one and mine use a drum and a disc brake, mine is a rear hub from a 125 Yamaha but nowadays you'd probably get away with something of a mountain bike. I mounted the caliper so it floated on a spring-loaded arm with the master cylinder so it automatically compensated but this is probably overkill, I'm not sure it ever did anything really!

Fran M wrote: Sorry to still disagree but I don't think the Munter allows "controlled" slippage. It just slips, same way as an ATC.
The idea that one could grip with more or less strength to let more or less rope slip is appealing but not realistic.
The Munter (or Tube) will just slip at lower loads for a weaker / lighter person and at higher loads for a heavier / stronger or more experienced belayer.

You may have misunderstood the control mechanism.  The rope doesn't slip through the climbers hand.  The climber's hand is positioned away from the knot and the fall load pulls the hand and arm to the knot.  In the CAI videos, what looks to be about a two-foot distance, maybe a bit more, is enough to stop the weight by the time the climbers hand arrives at the knot.  There's no slippage through the hand at all.  That's for a near factor 2 fall with steel weights, and that's what I mean by controllable slippage.  

You can do the same thing with a belay plate on the anchor.  Most belay plates seem to offer less friction than the Munter, so the amount of rope between brake hand and anchor might need to be longer.

rgold wrote:

You may have misunderstood the control mechanism.  The rope doesn't slip through the climbers hand.  The climber's hand is positioned away from the knot and the fall load pulls the hand and arm to the knot.  In the CAI videos, what looks to be about a two-foot distance, maybe a bit more, is enough to stop the weight by the time the climbers hand arrives at the knot.  There's no slippage through the hand at all.  That's for a near factor 2 fall with steel weights, and that's what I mean by controllable slippage. 

You can do the same thing with a belay plate on the anchor.  Most belay plates seem to offer less friction than the Munter, so the amount of rope between brake hand and anchor might need to be longer.

No slippage through the hand is far from controllable slippage to me, but that's just semantics. Even then, the CAI manual "Alpinismo su roccia, 2008" states the following thumb rule:

"For a fall directly onto the Munter, the slippage is around 1/3 of the fall length" (two times the length of rope out).

So 2 ft between Munter and brake hand might be ok for a FF1 - FF2 fall with only 1 meter of rope out.

They also say that having more than 60-70cm between brake hand and Munter is generally not possible at belay stances. So, for more than 1 meter of rope out, I'd expect slippage through the hand too, after it has reached the Munter.

Got references for those quotes Fran?  They go against my experience, which while limited, is more substantial than most climbers I suspect.

rgold wrote: Got references for those quotes Fran?  They go against my experience, which while limited, is more substantial than most climbers I suspect.

I edited my reply to include the name of the book. The Padova tower videos are great but fall / catch events happen so fast that is not easy to identify the slippage through the hand. Sometimes after the fall the instructor shouts the slipagge length and they seem longer than the initial brake hand - Munter distance. 

Fundamentally the CAI are right but the whole interaction between the belayer forces and what happens regarding braking force is somewhat complicated! As I've been in the forest all day with a chainsaw and am on my third beer I'll try to explain in the morning.

Watching the videos for the giga jul, I noticed that the belayer did not secure the belay strand when lowering a follower.  

While playing with mine, the friction goes to nothing with the rear of the giga jul is lifted far enough.   It the release modulated enough that securing the belay rope is unnecessary?

Does anyone have any thoughts on this?

Fran M wrote:

"For a fall directly onto the Munter, the slippage is around 1/3 of the fall length" (two times the length of rope out).

So 2 ft between Munter and brake hand might be ok for a FF1 - FF2 fall with only 1 meter of rope out.

Of passing interest only. Booklet from 50s/60s: Nylon rope and climbing safety by Tarbuck. Has example of UK style waist belay, eleven stone weight, 34 foot free fall, arresting slide 12 feet. No runners, ie presumably FF2, rope appears to run across edge of belay ledge. Recorded on cine film. Compares OK with slippage on Munter? 

Fran M wrote:

No slippage through the hand is far from controllable slippage to me, but that's just semantics. Even then, the CAI manual "Alpinismo su roccia, 2008" states the following thumb rule:

"For a fall directly onto the Munter, the slippage is around 1/3 of the fall length" (two times the length of rope out).

So 2 ft between Munter and brake hand might be ok for a FF1 - FF2 fall with only 1 meter of rope out.

They also say that having more than 60-70cm between brake hand and Munter is generally not possible at belay stances. So, for more than 1 meter of rope out, I'd expect slippage through the hand too, after it has reached the Munter.

There are a number of issues that confuse things especially when you start comparing belaying direct off an anchor with off the harness and when you compare FF2 with lesser fall factors, additionally complicated when the falls become larger. 

With small falls we know from testing that briefly we can grip the rope considerably more than we see from longer duration tests so short falls on a drop tower or in the climbing gym we can produce more braking force than longer falls. For working out belay device power we use the lower grip force as these are the only accurate ones we have AND no-one knows exactly how long this brief higher grip force can be held for or how high it is.
Using the normal values we know that achieving a braking force of 2.5-3.5kN is in the normal good range which invevitably means, as the CAI say, the slip must be ca. 1/3rd of the fall distance in a FF2 for any fall where slip occurs (a short fall it may not, or it may only be through the device but not through the belayers hand). Small amounts of slip aren´t normally noticed unless you are marking the rope to measure it (or taking it off the read-out´s) and half a metre or so would be of little interest, much more and it will be felt (the limit is generally thought to be around 1.6m before you get rope burns).
The initial slip through the device is usually at a fairly low force, it´s actually hard to hold your hand down and back against our normal grip force it´s not until the hand gets higher and nearer the device we are strong enough (or the hand hits the device).

In normal circumstances the fail-safe element is belayer lift, since we are all easily capable of holding our own weight when abseiling the extra grip force we normally impose when belaying means we can roughly speaking cope with producing an acceleration of about 3g on our bodies or actually produce 2.5-3kN force on the rope and lift the belayer to stop the faller before the rope will start to slip and for most falls this is enough. Take a FF2 and this safeguard goes out of the window as there is no belayer movement so the braking force of the device is quickly overwhelmed and the rope starts to slip through the belayers hand. And more than say 5m or so fall they may well get rope burns.

People who regularly use controlled slip through the hand generally wear gloves!

climber pat wrote:

I don't mean to be rude, but I do feel it important to put forth really good information if at all possible and I had asked about the rope previous to my reply.  In any case I am happy that you are willing to clarify what happened.

I still am unable to determine if you had several drops on the same section of rope before the sheath was damaged and core exposed of just one drop on a used rope.  If more than one drop do you have any idea how many?  What other devices where used in previous drops?  Where the knots untied and retied?  What brand/model of rope was used?  Was this somebody's rope who was willing to donate it to the cause because it was worn out or did Petzl pony up a new rope?  It is easy to imagine a test scenario which would give a very bad and potentially false impression of the giga jul.  For example test 3 times on a ATC, the 3 times on a muntner, then start testing with the giga jul with 6 fall factor 2 falls already on the section of rope.

In summary:

1. Was the rope new?
2. What brand/model rope?
3. If the rope was previously used, how much use?  (days climbing, very fuzzy, ready for retirement, looked good,...)
4. Was a different section of rope used for each device?
5. If the same section was used for multiple devices which devices were tested before the giga jul and how many drops for each device.
6. If a new section was used for the giga jul how many test falls before it failed.
7. Were the the giga jul and ohm tested 1st therefor being tested on the ends of a used rope?
8. It appears the fall length was about 10 feet (twice the fall from the anchor at a leaders shins)?

I have never even seen a giga jul so I don't have any real knowledge about it.  I ordered one today so I can play with one and form my own impression.  I have both the micro and mega jul but I thought both were finicky and gave up using them after looking at Jim Tritt's graphs on their holding power.

I had seen the 1st and 3rd video you linked above and find the technique intriguing especially using a munter hitch to belay.   I prototyped the ATC version of the fixed point belay a couple of years ago and was not very satisfied with it and have not tried it in a real climbing situation.

I have been working on building my own drop tower to test this and other scenarios that seem under evaluated or not even addressed by most UIAA/CE or vendor testing.  I have the measurement electronics and release mechanism worked out; I still need to get a winch to lift the weight and actually build the tower.  I have been testing by dropping small weights off of a ladder.  My long term plan is to make this an open source tower in the sense that I will, for free, drop stuff for people who supply the items to be tested.  I will document the process and measurements for free as long at the documentation and measurements are available to anyone wanting to look at it.  

So many questions, so little data.

1. We had maybe two drops max per end before switching to catching the fall with belay devices in an ABD set up - just to see what might happen, as an informal observation. The megajul, when in ABD mode for some reason never grabbed the load at all, so the load plummeted to the floor. With the Ohm, which is a great device when used according to manufacturer's recommendations, used as an ABD - it shredded the rope through its sheath and left the core in literal ribbons.

2. Unclear to me - i believe it was roughly 9.8 in diameter, did not ever know make and model/ manufacturer. (Hence none of this is, as stated before exact science in any way).
3. Rope looked good - some wear but by no means a fuzzy sheath - looked "healthy" as in, coloration was relatively fresh although not shimmery as a brand new rope,
4. Yes, we swapped ends, so each end probably saw 2 falls prior to the Ohm shearing it apart. Perhaps more but not many more. Again - no one claiming this to be in accordance with any scientific process. 

5.Other devices used previous to the "fatal" drop(s) included using a munter, and I believe an ATC guide, but in a redirected plate mode - it could have been a Reverso, I can't recall. The megajul that didn't engage when in ABD mode was also held prior to the Ohm drop that broke. Again - Ohm being used in a relative misapplication - using it as a direct belay off of an anchor and catching a factor 2 fall of an 80 kg mass. 

6.before what failed? The rpe never failed on the mega... the ega failed to engage the load and therefore the forces dissipated until the mass ultimately hit the floor. - perhas if this were higher up on a given route it could have come to a stop, but because the mass hit the floor with the height of the tower we had available, we didn't replay that scenario - perhaps once more to see if it was operator error on the mega. Again - 7 of us were observing and one of our colleagues who was psyched was up on the tower loading and using the belay devices, and I didn't have time to keep up with documenting each device each time between drops (was caught up in helping haul the mass back up for the next drop, etc). 

7. No. Mega was tested second to last. After probably as mentioned 4 maybe 5 drops total, with between 2 and 3 drops per rope end - same rope was used entire time until final failure. Ohm was tested last - after a few falls, yes. 

8. Maybe slightly more - 12-14 ft. The anchor was about 12 ft off the ground - and much of our informal obs were to see what happened if a lead climber were to fall, prior to placing pro for themselves and/or falling with their shins/ankles roughly at the anchor. So lead fall, at anchor, and sometimes a little higher - maybe 4 feet above the anchor. 

Climberpat - I think your idea of an open source tower is awesome. My second biggest takeaway from this workshop was being astounded/impressed. My biggest takeaways from this workshop were a) Fixed point belays are currently more common in CA and Europe more than the US. There are building arguments for the advantageous utility of this technique in American climbing, but with the caveats that come with this technique, it's tricky for the beginner or anyone absolutely new to this technique to employ the technique properly.... 

b) The forces we saw exerted on the 80kg mass in the observation stages were interesting to me: We typically say forces between 4 and 6 Kn, most of them registering at around 4.5 or 5 Kn. I was impressed by how relatively low the forces were, but still enough to compromise a poorly constructed climbing anchor. 

c)While there's only a few ways to employ this technique, the variables are myriad when we start swapping devices and hitches, and if there's gear placed first or not, etc. Simple, sensical technique with more than meets the eye and with a relatively limited body of testing and research - someone investing in finding these numbers and parameters in a more scientifically sound way is what we need at this point. 

climber pat wrote:

Thanks for the input.  I will give it serious consideration.  I was thinking about 10 meters.  I am very interested in testing belay devices and also controlled breaking of protection (simulating a piece pulling and the load falling onto the next piece).

In another thread you already explained to me why my initial thoughts on a controlled belay hand were terribly wrong.  I will look into what I can find that others are doing.  My current thought is a clamp calibrated to some level but that seems unlikely to be as repeatable as i would like.  Another idea floating around in my mind is a wheel connect to a motor controlled by a computer monitoring a speed sensor and strain gauge.  I worry about the response time of this design.  If you have a reference to a good design i would love to look at it. 

Yes - I think the taller the tower, the broader results possible without mass hitting the ground, or letting slippage occur until a final arrest of the falling mass and seeing what happens to the rope, etc. Our tower was adequate for our purposes, but could've been taller for stated reasons above.