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Post by gregggagliardi on Feb 28, 2013 17:42:46 GMT -8
Suggest we recommend as a best practice to extend the rappel device. Also suggest that we recommend using a Penberthy autoblock rather than the French prusik (ordinary autoblock). Further suggest that we recommend using dynamic (vis a vis static) cord for constructing the autoblock and other gear, made with accessory cord.
Gregg J. Gagliardi
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Post by nicklyle on Mar 7, 2013 1:35:28 GMT -8
Please describe/illustrate the penberthy auto block.
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Post by nickhunt on Mar 7, 2013 12:13:30 GMT -8
Nick, the Penberthy autoblock is a simple length of cord with a loop on either end (overhand or figure-8 on a bight), wrapped around the rappel line, with the loops clipped to a carabiner. It is very similar to the ordinary autoblock the Mounties currently uses/teaches, but is single-stranded.
Gregg, can you explain why you think the Penberthy is a better choice? To me, it just seems like one more specialized piece of gear a climber would need to carry. The nice thing about the French prussik is that it can be tied with a 4ft loop that is much more versatile (ascending, ratcheting, load transfers, etc.) Less clutter on the harness is usually better, IMO.
-Nick
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Post by gregggagliardi on Mar 7, 2013 12:31:37 GMT -8
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Post by gregggagliardi on Mar 13, 2013 17:48:38 GMT -8
The Penberthy is an all around versatile friction hitch. You can use it anywhere you might use an autoblock or Klemheist or Bachmann.
The main advantages of the Penberthy are: (1) you get more friction per inch of cord (2) it ties very quickly (3) it is really well behaved (unlike a prussik or autoblock that frequently get twisted and crossed and (4) its was invented by Larry Penberthy, pioneer climber and founder of MSR :>)
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Post by jimnelson on Mar 14, 2013 13:58:28 GMT -8
Side note about names.
Does anyone else think it's unlikely that Mr. Penberthy invented this friction hitch? maybe introduced to some.
I learned a very similar friction hitch that was introduced to me as a french prussik. The various names can be tricky some times. I always prefer more descriptive names when possible. Not always possible and some names more established than others, but names seem important when trying to cover a wide audience.
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Post by nicklyle on Mar 14, 2013 22:04:56 GMT -8
There is a whole raft of friction hitches that tree climbers use. Arborists become attached to their favorite hitches and swear by them. The one they call a French Prussik is a bit different than the Penberthy. I have seen more than one knot called a French Prussik.
Trouble free and easy handling is valuable in a friction hitch. Rappelling is a big deal, and I have noticed that people don't bother with a friction hitch back up most of the time, though it adds a very large margin of safety. One reason could be that the commonly used auto block can be a bit fussy to use, especially without an extension of the rappel device. If you tie it just right with just the right length loop for the rope diameter and use an extension on the belay device it is fine. Most friction hitches are quite sensitive to the size and material of the cord used as well as the length of loop, number of wraps, etc.
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Post by gregggagliardi on Mar 15, 2013 9:32:44 GMT -8
Try the Penberthy autoblock. You will like it. It is quick to tie, dresses itself while you tie it, holds well, slides well (including sliding under a load) and holds it coils in palce, unlike other friction knots that get all twisted up.
To tie it onto a rope try this. Hold a section of rope in a horizontal position. Pinch the left end loop against the rope and let the cord drape over the rope. Now with arms outstretched twirl the rope (carefully avoiding hitting your face with the loose end of the cord. The cord will coil around the rope several times. Compress the coils together and perhaps add another coil or two. Clip the looped ends with a locker and you are done. With a little practice you can perform this operation on a vertical section of rope. Alternately, you can spin the cord around the rope, but the rope must be taut.
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Post by nicklyle on Mar 24, 2013 17:45:58 GMT -8
The Penberthy sounds functionally just like what tree climbers call an "eye-to-eye Prussik" which is a length of accessory cord (usually a heat resistant cord) that has a tight-eye spliced in each end. Old school climbers use knotted cord, but now it is common to use the spliced lengths of cord for the more sophisticated friction knots, such as the Valdotain Tresse.
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Post by jimnelson on Mar 25, 2013 7:42:24 GMT -8
I like the more descriptive name
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Post by jasonmartin on Aug 3, 2013 8:14:09 GMT -8
I think extended rappels are great. I tend to extend my rappels about 80% of the time. This is primarily because it: - Increases the speed of setting up a rappel. Multiple people can set-up simultaneously.
- Increases the safety. You can check one another, and if someone does make a mistake and doesn't capture both strands, the fact that others are fixed in the rope freezing it in place makes a potentially fatal mistake, nothing more than a minor incident.
- Increases security for less experienced climbers. They can be checked ahead of time.
Sometimes I don't extend my rappel when I'm in a single pitch sport climbing setting... This is because it doesn't necessarily increase my security if I'm the only one at the top cleaning an anchor. It can also be a pain if I'm cleaning a high anchor and I'm a bit below it on my device. My experience is that a Penberthy and a regular autoblock are extremely similar in functionality. In other words, I'm not sure that I'd agree that one is better than the other. I'd be curious to hear why some think one is better than the other. So far my experience has always been that people have personal preferences...but I haven't heard anything compelling about why one is better. Jason
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Post by Deling Ren on Feb 10, 2014 17:58:59 GMT -8
Penberthy is neat, but the cord is limited to one application. OK, maybe there are other applications, but not as versatile as a autoblock hitch with a hero loop. I personally don't find autoblock hitch hard to dress as long as the loop is made of supple material.
Why dynamic cord for autoblock?
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Post by gregggagliardi on Feb 11, 2014 10:52:25 GMT -8
The conventional autoblock also works well. The penberthy (aka valdotain tresse [VT]) is an even more versatile friction hitch. It goes on the rope in neat coils in couple of seconds. (good as a third hand rappel back-up; good as a rope grab for other purposes such as rescue, or use in ascent systems) It grabs exceptionally well (some consider it safer than an autoblock because it is less prone to slipping) It is easily moved along the rope after loading (this is almost magical and must be experience to be believed) Cord diameter is not an issue; it can be tied with rope on rope, Good to know in a pinch. When rigged with a pulley ( as shown in the photo below) it makes a great ascension rig (a preferred ascension method among professional arborists who spend lots of time moving up and down ropes to make their living. 6.5 Bluewater dynamic is supple, very easy to work with. I now use Sterling 6.8 mm Hollow Block which is even more supple, stronger, more durable and better able to handle heat generated by friction (melting temp is 900 F).
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