Mine is 6.8. I had to do 5 wraps on 8mm. Barely able to clip it in. But I weigh a buck-70 and have only played in the yard with 8mm not fully loaded down so that may be something.
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Rappelling 101
- Thread starter Patriot
- Start date
Mine is 6.8. I had to do 5 wraps on 8mm. Barely able to clip it in. But I weigh a buck-70 and have only played in the yard with 8mm not fully loaded down so that may be something.
pesqimon
Well-Known Member
For clarification, you used a french prusik (aka autoblock)? Sometimes an extra wrap is all it takes. On the other hand it doesn’t take much bite to stop you because of the combination with the belay device.
If you can post a pic of the setup, showing the hitch, it would be nice.
If you can post a pic of the setup, showing the hitch, it would be nice.
SecretAgentMan
Active Member
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- Dec 31, 2019
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I can try to post a pic later. Yes, a french prusik. I used as many wraps as I could get with the 13.5" loop. It wanted to hold, but it still was slowly creeping through on me. Enough so, that I felt like I needed to bind the brake end tighter against the ATC. If I was perfectly still and let my weight rest on the autoblock, it'd hold, but much fidgeting around (i.e. removing my stick), and it would want to creep again.
I don't claim to know much about climbing gear, but it seem to me that a 6.8 mm accessory rope for friction on 8mm that is a tad slippery isn't ideal. That's 85% of the main line diameter. I was under the impression that the target is more along the lines of 60-75%. I think I saw somewhere else here on the forums that someone didn't have much luck with the same setup. I use a Mad Rock HMS hulk round 'biner for the ATC. I suppose I could add an extra 'biner to the ATC and create more friction, but I don't want to have to deal with two if I don't have to. Regardless, the 6.0 loop works great.
All a testament to why to try it at ground level in the yard before 25' up a tree in the dark with it raining.
pesqimon
Well-Known Member
Indeed 6mm cord is more appropriate for 8mm line
I attached a spring scale to the tag end of my rope and it took 10 pounds of force to hold my position. For an autoblock below the ATC, almost any thin rope or even paracord would provide this. No need for this to have thousands of pounds of breaking strength.
pesqimon
Well-Known Member
That’s a pretty bad suggestion. There’s more to climbing materials than breaking strength. I wouldn’t suggest anyone use anything besides approved components for rappelling
SecretAgentMan
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Yeah, I absolutely want my autoblock to be able to hold my weight. If it were to break and I don't have a brake hand on the line, that tag end is coming through my ATC, in rapid fashion, as I quickly make my way to the earth.
I did use paracord a few times for an autoblock below the ATC. It worked fine. I keep a small loop with my emergency rapel ATC. I have used 5/16 polyester rope with a WLL of 230 pounds from Lowes for an autoblock and it worked fine. Like I said it must be able to hold 10 pounds force. I wouldn't support my full weight on this rope. If someone doesn't know what they are doing, they could be in trouble. That is true with most everything in this world.
pesqimon
Well-Known Member
Who knows how you performed your so called test that lead you to type that a rope from Lowes is acceptable for keeping you from hitting the ground.
Anyone else reading this, please spend a couple of bucks on real ropes that have been designed and tested for this application. I do mean a couple of bucks. For something like $5 you could have the best cord for this application.
SecretAgentMan
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It doesn’t matter if it’s grass garden twine, if it can’t hold my weight while hands free, it’s not doing its job. WLL doesn’t matter much if I’m lying dead or paralyzed at the bottom of rappel with a perfectly intact autoblock still attached to my line. It does when my full weight is on the autoblock. Likewise, and maybe I’m doing something wrong, but that ATC isn’t holding anything if I don’t have a hand on the brake.
Seems to me that in that time that I don’t have a hand on the brake line, I’m fully relying on the accessory cord used to tie the autoblock to keep me airborne. While not serving as a fall arrest, it is serving as a means of descending progress capture
In short, it must be capable of both: enough WLL to hold my full weight and the ability to provide friction.
Seems to me that in that time that I don’t have a hand on the brake line, I’m fully relying on the accessory cord used to tie the autoblock to keep me airborne. While not serving as a fall arrest, it is serving as a means of descending progress capture
In short, it must be capable of both: enough WLL to hold my full weight and the ability to provide friction.
Are you putting this above your ATC so it supports your full weight? Check out several Youtube videos by accredited climbing organizations for the proper way to run an autoblock. If you are using it above your ATC then forget all my previous posts. Knowledge is worth more than great climbing gear.
SecretAgentMan
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Below. Attached to a lineman’s loop.
It’s common sense and good practice to use rated material above or below your ATC. There is no excuse for using something lesser.
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Sent from my iPhone using Tapatalk
I think I would be just as concerned with how the prusik deals with friction while rappelling. I would hate to melt through the cord while sliding down the rope, no matter how much weight it is holding. Use cordage designed for the intended purpose. I cannot melt the ends of the sterling cordage that @DanO sells to use with Oplux rope. Paracord melts and burns easily.
I’m all about using the right stuff for this. The notion of this being the place where I cut a corner just seems silly at best.
That said, isn’t there something about the Sterling Hollow Block (being flatter and hollow) that makes it better on nearer sized ropes than it would be if it were round cord of the same 6.8 diameter? I’m using it on 9mm HTP (and I’m not a small fella) and it holds pretty darn well in a four-wrap French prusik. I have that same orange cord and an extra jammy I may try as well next time just to see how it’s different. Anyway, I was really just curious if the Hollow Block is treated the same way in terms of its size.
That said, isn’t there something about the Sterling Hollow Block (being flatter and hollow) that makes it better on nearer sized ropes than it would be if it were round cord of the same 6.8 diameter? I’m using it on 9mm HTP (and I’m not a small fella) and it holds pretty darn well in a four-wrap French prusik. I have that same orange cord and an extra jammy I may try as well next time just to see how it’s different. Anyway, I was really just curious if the Hollow Block is treated the same way in terms of its size.
Yes, it flattens when under tension. I use it on 9mm HTP as well. Works great.
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I just got out my emergency ATC and my paracord prusik loop. Here I am hanging from my pullup bar with an ATC using a paracord autoblock with a rappel extension. 10 pounds will always be 10 pounds so if the paracord can withstand 10 pounds I will be fine. Don't try this unless you know what you are doing.
NikoTheBowHunter
Well-Known Member
Anyone used 5mm titan rope for rappelling? (Tensile Strength: 3,100 lbf. (13.7 kN)). Thinking I might pick up some and give it a try. As I rappel using a figure 8, any size rope will work. With the goal of shaving weight and making every ounce count, thinking this might be a good way to cut down on some bulk (currently using 10mm rope).
Ran across this which makes me think why not: https://www.summitpost.org/phpBB3/how-do-rappel-off-very-thin-rope-t66735.html
Ran across this which makes me think why not: https://www.summitpost.org/phpBB3/how-do-rappel-off-very-thin-rope-t66735.html
I just got out my emergency ATC and my paracord prusik loop. Here I am hanging from my pullup bar with an ATC using a paracord autoblock with a rappel extension. 10 pounds will always be 10 pounds so if the paracord can withstand 10 pounds I will be fine. Don't try this unless you know what you are doing.
I just don't understand why you are carrying a paracord prusik for a backup. A prusik made for the application is about the same weight/bulk as paracord. Not to mention in an emergency situation it can be used for other things since it has strength.
I have rappelled with Sterling 6mm TRC and a Rock Exotica Mini 8. It works fine. I understand the limits and risks.