SPAR ropes

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SPAR ropes

Postby bobby49 » Jul 22, 2019 12:43 am

Most cavers use something like 10mm or 11mm rope for standard ascending and descending. If vertical distances are short, like 50 feet, then sometimes something as small as tough 9mm rope might be used.

Some cavers carry a lightweight kit for Small Party Assisted Rescue. This might include some small ropes for assembling haul systems. Since these do not normally see standard ascender/descender hardware, often they are small diameter and will fit just about any pulley. What kind of static rope do you use for this?

Some have suggested 150 feet of 7mm cord.
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Re: SPAR ropes

Postby NZcaver » Jul 24, 2019 6:51 pm

bobby49 wrote:Some cavers carry a lightweight kit for Small Party Assisted Rescue. This might include some small ropes for assembling haul systems. Since these do not normally see standard ascender/descender hardware, often they are small diameter and will fit just about any pulley. What kind of static rope do you use for this?

Some have suggested 150 feet of 7mm cord.

Commonly, 7 or 8mm cord. Length is up to you, but 150 feet seems like overkill. If you plan to use the entire length as a 4:1/5:1, just use a shorter length as a piggyback jigger and progress capture on main rope. With thinner diameter cord, the "strength" is in equally distributing the load between multiple strands (and pulleys). Using that logic, years ago I decided to build a jigger out of 5mm cord and miniature paraglider pulleys. Extension is from about 1-4 feet, from memory. Doesn't weigh much, and fits in a pocket. Works great. Several years later, Mammut came out with a similar concept they called a "Rescyou" - now apparently discontinued.

Just some food for thought.

My creation:
Image

Rescyou: https://www.youtube.com/watch?v=u7m-xT6NJ4k
Image
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Re: SPAR ropes

Postby trogman » Jul 30, 2019 5:31 am

NZcaver wrote:
bobby49 wrote:Some cavers carry a lightweight kit for Small Party Assisted Rescue. This might include some small ropes for assembling haul systems. Since these do not normally see standard ascender/descender hardware, often they are small diameter and will fit just about any pulley. What kind of static rope do you use for this?

Some have suggested 150 feet of 7mm cord.

Commonly, 7 or 8mm cord. Length is up to you, but 150 feet seems like overkill. If you plan to use the entire length as a 4:1/5:1, just use a shorter length as a piggyback jigger and progress capture on main rope. With thinner diameter cord, the "strength" is in equally distributing the load between multiple strands (and pulleys). Using that logic, years ago I decided to build a jigger out of 5mm cord and miniature paraglider pulleys. Extension is from about 1-4 feet, from memory. Doesn't weigh much, and fits in a pocket. Works great. Several years later, Mammut came out with a similar concept they called a "Rescyou" - now apparently discontinued.

Just some food for thought.

My creation:
Image

Rescyou: https://www.youtube.com/watch?v=u7m-xT6NJ4k


Image


NZ- Somehow the cord on your creation appears (to me) to be larger than 5 mm. What type of cord did you use?
I have been using 5 mm Tech Cord http://onrope1.com/rope-webbing-cordage/tech-cord-5mm/for several years now for my ascender tether. It is rated at 5K lbs, and is nearly impossible to cut. I get some strange looks from my fellow cavers when they see it, and I have been asked about it more than once. One fellow told me that he didn't care how strong it was, he couldn't use something that thin because it just freaked him out trusting his life to something that thin. :yikes: The only issue with something that thin is that it doesn't grip in very well in ascenders nor does it have enough bulk to provide much braking with most descent devices. But that's not what I am using it for, so that's not a problem for me.

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Re: SPAR ropes

Postby NZcaver » Jul 30, 2019 7:03 am

trogman wrote:NZ- Somehow the cord on your creation appears (to me) to be larger than 5 mm. What type of cord did you use?
I have been using 5 mm Tech Cord http://onrope1.com/rope-webbing-cordage/tech-cord-5mm/for several years now for my ascender tether. It is rated at 5K lbs, and is nearly impossible to cut. I get some strange looks from my fellow cavers when they see it, and I have been asked about it more than once. One fellow told me that he didn't care how strong it was, he couldn't use something that thin because it just freaked him out trusting his life to something that thin. :yikes: The only issue with something that thin is that it doesn't grip in very well in ascenders nor does it have enough bulk to provide much braking with most descent devices. But that's not what I am using it for, so that's not a problem for me.

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Hi Stephen,

Hmm, I thought my cord was 5mm but it's possible it's 5.5mm or 6mm. I don't have it on hand. It's regular accessory cord, very flexible, nothing special. I also use a rather stiffer, tighter weave 5mm Tech Cord on my frog rig, but mine is my footloop cord (with tubing to protect the actual loops). It has held up very well over the years. I would be hesitant to use it as an ascender tether. Despite its strength and resistance to damage, it has absolutely no stretch and would not be a good choice as a tether for arresting a potential shock load, even one less than FF1. I use a piece of 9mm dynamic rope for that instead, although I've seen others go as thin as 8mm dynamic.
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Re: SPAR ropes

Postby trogman » Jul 30, 2019 3:54 pm

NZcaver wrote:
trogman wrote:NZ- Somehow the cord on your creation appears (to me) to be larger than 5 mm. What type of cord did you use?
I have been using 5 mm Tech Cord http://onrope1.com/rope-webbing-cordage/tech-cord-5mm/for several years now for my ascender tether. It is rated at 5K lbs, and is nearly impossible to cut. I get some strange looks from my fellow cavers when they see it, and I have been asked about it more than once. One fellow told me that he didn't care how strong it was, he couldn't use something that thin because it just freaked him out trusting his life to something that thin. :yikes: The only issue with something that thin is that it doesn't grip in very well in ascenders nor does it have enough bulk to provide much braking with most descent devices. But that's not what I am using it for, so that's not a problem for me.

Trogman :helmet:

Hi Stephen,

Hmm, I thought my cord was 5mm but it's possible it's 5.5mm or 6mm. I don't have it on hand. It's regular accessory cord, very flexible, nothing special. I also use a rather stiffer, tighter weave 5mm Tech Cord on my frog rig, but mine is my footloop cord (with tubing to protect the actual loops). It has held up very well over the years. I would be hesitant to use it as an ascender tether. Despite its strength and resistance to damage, it has absolutely no stretch and would not be a good choice as a tether for arresting a potential shock load, even one less than FF1. I use a piece of 9mm dynamic rope for that instead, although I've seen others go as thin as 8mm dynamic.


Is your concern that the rope would break in the case of a sudden loading with a short fall? I suppose that makes sense, but a 5K strength rope is not likely to break in such a situation, even though it is static. I'm pretty sure the ascender would cut the main rope in two before the tech cord breaks. If fact, the danger of an ascender cutting the rope is one reason NOT to use one where any significant fall factor is a possibility.

Am I missing something here?

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Re: SPAR ropes

Postby NZcaver » Aug 3, 2019 4:22 am

trogman wrote:Is your concern that the rope would break in the case of a sudden loading with a short fall? I suppose that makes sense, but a 5K strength rope is not likely to break in such a situation, even though it is static. I'm pretty sure the ascender would cut the main rope in two before the tech cord breaks. If fact, the danger of an ascender cutting the rope is one reason NOT to use one where any significant fall factor is a possibility.

Am I missing something here?

Yes, you're missing something. It's not just about the rope breaking at its 5K *STATIC* MBS, it's about a shock load being absorbed and how that peak force is spread between the rope, the knots, the hardware, the harness, and the body. And as you said, potentially through an ascender clipped to a static rope.

If you have access to copies of Alpine Caving Techniques, On Rope, Vertical, Life On A Line, and other definitive vertical caving publications, read up on what they recommend for cowstails and ascender tethers. Also note that best practices for rock climbing and mountaineering adamantly insist on not using Spectra or Dyneema etc cords/webbing in any life safety application that could see a sudden shock load, for the same reasons.
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Re: SPAR ropes

Postby trogman » Aug 5, 2019 4:30 pm

NZcaver wrote:
trogman wrote:Is your concern that the rope would break in the case of a sudden loading with a short fall? I suppose that makes sense, but a 5K strength rope is not likely to break in such a situation, even though it is static. I'm pretty sure the ascender would cut the main rope in two before the tech cord breaks. If fact, the danger of an ascender cutting the rope is one reason NOT to use one where any significant fall factor is a possibility.

Am I missing something here?

Yes, you're missing something. It's not just about the rope breaking at its 5K *STATIC* MBS, it's about a shock load being absorbed and how that peak force is spread between the rope, the knots, the hardware, the harness, and the body. And as you said, potentially through an ascender clipped to a static rope.

If you have access to copies of Alpine Caving Techniques, On Rope, Vertical, Life On A Line, and other definitive vertical caving publications, read up on what they recommend for cowstails and ascender tethers. Also note that best practices for rock climbing and mountaineering adamantly insist on not using Spectra or Dyneema etc cords/webbing in any life safety application that could see a sudden shock load, for the same reasons.


I did look through On Rope and couldn't find anything on ascender tethers. Do you know what page # or chapter to look in?

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Re: SPAR ropes

Postby trogman » Aug 5, 2019 4:46 pm

I was just shopping on the ORope1 website and came across this:
http://onrope1.com/lanyards/or1-adjustable-lanyard/

This lanyard is specifically made for use with a QAS, and is made with static rope.

I know this store is now owned by Wm Shrewsberry, but I am pretty sure this and most of the other OR1 gear was originally designed by Bruce Smith.

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Re: SPAR ropes

Postby NZcaver » Aug 6, 2019 7:17 pm

trogman wrote:I was just shopping on the ORope1 website and came across this:
http://onrope1.com/lanyards/or1-adjustable-lanyard/

This lanyard is specifically made for use with a QAS, and is made with static rope.

I know this store is now owned by Wm Shrewsberry, but I am pretty sure this and most of the other OR1 gear was originally designed by Bruce Smith.

Yeah, I'm aware of this concept and some of Bruce's other creations. Some of us used these decades ago, before a commercial option was available. I soon retired mine because it was a little too bulky and cumbersome and there are other ways to achieve the same result. The Prusiks on that so-called "QAS" effectively make it dynamic, because they will usually slip-and-grab under significant force thereby reducing the peak force on your system.

Look up cowstails. If you're using an ascender (and tether) as fall prevention, it's basically the same role as a cowstail but with a gripping attachment to a rope instead of clipping in direct to an anchor.
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