French Wrap Rappel Safety Myths Debunked

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French Wrap Rappel Safety Myths Debunked

Postby TinY » May 31, 2007 12:43 pm

The French Wrap rappel safety has been the subject of much discussion and many incorrect opinions have been expressed about its use or application. I have been using and promoting the use of the French Wrap for 6 years and would like to provide insight on several of the myths associated with previous discussions.
The French Wrap is an auto block knot placed below the rappel device attached to the leg loop of your harness. I have successfully used the French Wrap with racks of all types and sizes, figure 8's, munter hitches, and bobbin type devices.
The French Wrap is not a silver bullet approach to rappel safety. It's use is no substitute for proper training, practice and experience with the rappel device you choose to use. The French Wrap must be properly attached to you harness and adjusted properly depending on rope conditions, harness configuration, rappel device used, and rappel conditions for it to function properly.
Use of the French Wrap is as much as a rappel technique as it is a rappel safety device. Proper use of the French Wrap must be learned and practiced to be effective. When used properly by an experienced rappeller, it will arrest an out of control rappel and prevent you from falling to your death should you become injured or incapacitate on rope by illness or rock fall. The French Wrap will also prevent an out of control rappel should you experience unexpected rope or rappel conditions during your descent.
The French Wrap is a second life support attachment while rappelling. Should you experience a rappel device failure or become detached from your rappel device, the French Wrap will keep you attached to the rope and prevent you from falling to your death.
The French Wrap will engage stopping your rappel in you panic and let go of it. The French Wrap will engage stopping your rappel if you panic and squeeze it tightly. The French Wrap does not interfere with normal use of your brake hand when properly placed in your rappel system. Both hands can be used to manage your rack or rappel device during your rappel when using the French Wrap.
The French Wrap will effectively provide a soft lock off of your rappel device when rope weight prevents a hard lock off on long rappels. Proper use of the French Wrap to provide a soft lock for your rappel device on long drops requiring management of rope pads makes these lips easier to cross.
The French Wrap can be used with over the hip rope placement or between the leg rope placement. The French Wrap can and has been used on long drops up to 2650' at El Cap. The French Wrap can and has been used on tandem rappels up to 2650' at El Cap and triple tandem rappels of 1150' at Golindrainious.
The French Wrap has been demonstrated effectively stopping rappel weights of 400 lbs without damaging the rope. The French Wrap will not cut a rope when engaged at high rappel speeds like mechanical devices will under shock load conditions.
The French Wrap WILL NOT allow you to change rope position during a rappel from on side of the body to the other to fully capture the bottom bar of a rappel rack. It will not prevent use of the bottom bar even when the bar is not fully captured by the rope and in my experience does not hinder the proper operation of a rappel rack.
When used properly by trained, practiced and experienced rapellers, the French Wrap will prevent injury and save your life in an emergency rappel situation.
If your FEET are beyond your last STATION..... YOU ARE SCOOPING! :-( See ya on station and Looooooog Rope Soon!
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Re: French Wrap Rappel Safety Myths Debunked

Postby NZcaver » May 31, 2007 6:21 pm

Some really good information there. :kewl:

TinY wrote:The French Wrap will not cut a rope when engaged at high rappel speeds like mechanical devices will under shock load conditions.

This is probably true in almost every situation, but I wonder if that old myth about the Prusik "never" severing/stripping/damaging the rope applies to this friction hitch too? If someone uses cordage that is too thin, or even just a main rope that is really gritty, in the unlikely event of a severe shock load the hitch may actually bind tight instead of slipping - causing damage to the rope. This has been proven to occur with a Prusik under certain test conditions, and however rare it may be for a rappel safety to fail this way, I'm thinking it could still happen. Of course in such an event, you probably have better odds of surviving with some kind of safety than without one... so this is mostly academic.

The French Wrap is an auto block knot placed below the rappel device attached to the leg loop of your harness.

Not to be pedantic, but I'm just curious here. Isn't "Autoblock" or "Autobloc" the original (and therefore possibly the more correct) term for this particular hitch? Anyone know the history of this?

There's also other threads on the DB that discuss this hitch in detail, including:
French Wrap self-belay
Rappelling? You don't need no stinking safety
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Re: French Wrap Rappel Safety Myths Debunked

Postby TinY » May 31, 2007 9:30 pm

TinY wrote:The French Wrap will not cut a rope when engaged at high rappel speeds like mechanical devices will under shock load conditions.

This is probably true in almost every situation, but I wonder if that old myth about the Prusik "never" severing/stripping/damaging the rope applies to this friction hitch too? If someone uses cordage that is too thin, or even just a main rope that is really gritty, in the unlikely event of a severe shock load the hitch may actually bind tight instead of slipping - causing damage to the rope.

This is a very good point I would like to expand on. Almost all accidents happen when a series of small events combine to create a dangerous condition. Using the wrong size cord for a French Wrap would be one of these. Using very dirty gritty rope for a rappel would be another one. The French Wrap when properly used is made from a prussik loop that is about 75% of the rappel rope. With the common 11mm caver rope, the correct size for the French Wrap is 8mm.
Properly used, the French Wrap will stop an out of control rappel without cutting the rope.

TinY wrote:The French Wrap is an auto block knot placed below the rappel device attached to the leg loop of your harness.

Not to be pedantic, but I'm just curious here. Isn't "Autoblock" or "Autobloc" the original (and therefore possibly the more correct) term for this particular hitch? Anyone know the history of this?

"Autoblock" or "Autobloc" may well be the correct term for this hitch but the spell check for this board suggested "auto block" so I let it go at that for the post. Gordon Birkhimer's article in the NSS News on the French Wrap does explore some of the correct terms for this hitch.
As for the history of the name "French Wrap", I coined this term after learning of this method of self belay from Van Bergen in his reply to a post of mine on this discussion in 2000.

Re: Euro prusik below decender self belay?

Posted by: Van Bergen on June 12, 2000 at 10:53:12:
In Reply to: Euro prusik below decender self belay? posted by Tiny Manke on June 08, 2000 at 19:46:21:

I found out from the more experienced members of Dayton Underground Grotto, who have been using it for years. They didn't know its "real" name, only that it was French. It's not a prusik, but four simple wraps starting at the top; both ends have a loop and are attached to your seat harness with a biner (preferably to the leg loop on your control hand side). The end loop, the size cord to use, its length, and the number of wraps are subject to experiment.

He was not sure of the correct name but thought it was French and the hitch was made with 4 wraps of a prussik loop. Correct or not it seems to have stuck and the use of an "autoblock" knot below a rappel device as a self belay rappel safety is more of a technique than a simple hitch.

See ya on a long rope!
TinY
If your FEET are beyond your last STATION..... YOU ARE SCOOPING! :-( See ya on station and Looooooog Rope Soon!
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Postby knudeNoggin » May 31, 2007 10:45 pm

Here is a section of Mark Adams's (arborist) "Son of Hitch: A Genealogy of Arborists'
Climbing Hitches" article (which can be found in pdf on http://www.treebuzz.com):

The word “autoblock” has been used in some English-language knot books to refer to a French Prusik.
“Autoblock”, however, is a corruption of the French “autobloquant”, which means “self-jamming”.
It is used to refer to a group of slide-and-grip knots and is probably better translated into the English term “friction hitch”.

Which assertion is I believe confirmed by Bob Thrun, as well.

:exactly:
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Re: French Wrap Rappel Safety Myths Debunked

Postby Bob Thrun » Jun 4, 2007 7:18 pm

TinY wrote:
TinY wrote: As for the history of the name "French Wrap", I coined this term after learning of this method of self belay from Van Bergen in his reply to a post of mine on this discussion in 2000.

TinY


It is unfortunate that TinY invented another name for a hitch that already had three names.

Machard -- Geroges Marbach told me that it was invented by Machard, a French mountaineer. I have no access to French mountainnering literature and do not understand French. I would like to find out the original publication of this hitch.

Autobloc, autoblock, or auto block -- The generic French term for hitches that can be used to grip a rope is "noeuds autobloquant". I can imagine the conversation between an English-speaking climber and a French climber: "What do you call this knot?", "Autoblocquant". I would like to find out when "autoblock" entered the climbing literature. I would be willing to search thru 10 or 20 years of climbing magazines and books from 1970 to 1990 or 1975 to 1985. I can't find a climbing book collector or club with a library. I can think of several cavers who have complete collections, There are more climbers than cavers.

French Prusik -- I can think of five different hitches that are called "French Prusik". Autoblock and French prusik are both used in climbing books and magazines. Sometimes I think one term is more popular and simetimes the other.

I did trace "lark's foot hitch" to a typo in Bill March's book, Modern Rope Techniques. Because of this error, the term "tete d'alouette" (head of lark) in the french edition of Marbach's book got translated to "lark's foot".
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Postby paul » Jun 5, 2007 6:34 am

FWIW, while on a rock-climbing course back in the 80's, I was taught to use this knot while abseiling (prusik loop wrapped 4 or so times around the rope with both ends clipped together with a karabiner, and the karabiner then clipped to the harness leg-loop on the same side as the controlling hand - and the knot is gripped by the controlling hand during descent).

It was referred to as an "Autobloc" which, because of the way it is spelled, I always believed to be French.
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Postby YuccaPatrol » Jun 5, 2007 7:19 am

Regardless of the origins of this method or the history behind the names used to describe it, I am looking forward to learning how to increase my safety while rappelling.

I really like the idea of not falling to my gruesome death.
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Postby Ralph E. Powers » Jun 5, 2007 9:27 am

YuccaPatrol wrote:Regardless of the origins of this method or the history behind the names used to describe it, I am looking forward to learning how to increase my safety while rappelling.

I really like the idea of not falling to my gruesome death.

Practice, practice, practice... it's what I've been saying.


Besides the sudden stop at the end of your fall isn't as painful as you might think.
Without the possibility of death, adventure is not possible. ~ Reinhold Messner


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Postby l lambert » Jun 5, 2007 9:33 pm

Ralph E. Powers wrote:Practice, practice, practice... it's what I've been saying.


:exactly: Leo
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Postby hunter » Jun 6, 2007 9:37 am

The French Wrap is a second life support attachment while rappelling.

I understand everything except this point. In the event of one's rappel device coming completely off the rope is this really a "second life support"? For climbing, many harnesses are not designed to use a leg loop for life support. I suspect most cave harnesses are not rated for full body weight on a leg either but maybe someone can correct me if I'm wrong here.

James
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Postby chh » Jun 6, 2007 12:39 pm

hunter wrote:
The French Wrap is a second life support attachment while rappelling.

I understand everything except this point. In the event of one's rappel device coming completely off the rope is this really a "second life support"? For climbing, many harnesses are not designed to use a leg loop for life support. I suspect most cave harnesses are not rated for full body weight on a leg either but maybe someone can correct me if I'm wrong here.

James


Why include leg loops if they couldn't support body weight? While they may not be designed to operate in this fashion leg loops should provide fall protection, though not very comfortable protection at that. I've always thought that those fast adjust buckles, such as are becoming more widely used, might be hazardous with a french wrap on the leg loop because the loop might pull against the buckle in the event you loaded it in a fall, thus loosening it and further compromising your already screwed up situation.

But as far as I know James, leg loops are designed for life support. Otherwise the redundancy in that particular part of the system isn't really redundant, is it? I've taken (and caught) some sizeable whippers in my climbing harnesses, exerting much more force than body weight on them. Granted the force is applied to the system, and it would be nigh on to impossible to calculate the actual force on the individual leg loops, but I have more than a hunch that I (and my harnesses) would have seen some damage over the years if leg loops were not designed to be life support.
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Postby hunter » Jun 6, 2007 1:26 pm

chh, for caving harnesses you may be correct, my petzl certainly has a tough looking leg loop. I'd be interested to hear if this is actually tested though.

For climbing harnesses I disagree with your conclusion that the leg loop is always a life support. The leg loops help for comfort and fall orientation but the harness is rated for attachment at specific points, not just anywhere (except one I can't remember the name of).

As an example consider the popular black diamond bod harness:
http://www.bentgear.com/product_info.php?products_id=963&engine=adwords!3869&keyword=%28Black+Diamond+Bod+Harness%29&match_type=
Click on the larger image and check out the plastic leg loop buckles. I do not believe that these are rated for life support.
Metal buckles are harder to judge but my gut feeling is that leg loops are not all rated or tested by the manufacturer to serve as a primary attachement.

I'm not trying to dismiss the autoblock, just pointing out a caveat I think is worth considering.

James
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Postby Dwight Livingston » Jun 6, 2007 1:29 pm

From a Mammut brocure on their harnesses, not just one type but in general . . .

In our numerous laboratory tests we
have developed constructions which transfer
around 80% of the fall energy onto the leg
loops. Thus the energy from the body’s centre
of gravity mostly effects the thighs. The
waist band protects and stabilizes the body
in an anatomically favorable sitting position.

My Superavanti and similar caving harnesses have identical webbing and buckles for the waist strap and for the leg loops. And should you loose either of the attachement loops, you'll be hanging from the leg loops only.

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Postby hank moon » Jun 6, 2007 1:38 pm

hunter wrote:
The French Wrap is a second life support attachment while rappelling.

I understand everything except this point. In the event of one's rappel device coming completely off the rope is this really a "second life support"? For climbing, many harnesses are not designed to use a leg loop for life support. I suspect most cave harnesses are not rated for full body weight on a leg either but maybe someone can correct me if I'm wrong here.

James


Good point, Hunter. A leg loop is NOT a second life support attachment.

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Postby NZcaver » Jun 6, 2007 10:31 pm

hank moon wrote:A leg loop is NOT a second life support attachment.

Especially if your harness is like mine, and doesn't have actual leg loops! :shock:

(If you're confused about this, check out the design of the GGG Ultralight harness here - scroll down.)

I agree with Hank and Hunter. I would not be comfortable telling people they can rely on the hitch as an effective "second life support attachment" when it's only attached to one thigh. Perhaps it will save you when your descender spontaneously explodes... but perhaps not.
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