Descending 3/8" kern SRT?

Sterling’s 3/8” HTP measures more like 10.5 mm and hitches behave just like a larger rope with an appropriately sized hitch cord, 7 and 8mm have worked great for me. There are friction hitches that can descend on a fixed rope, but would create too much heat if used for a fast emergency descent. If some type of descending device is going to be used, the hitch only has to grab reliably and not bind up after being loaded.
 
Hi Burrapeg,
Curious when you made the wrench/bird upper portion of the bone did you run pure cylindrical bollards or have you tried profiled (scooped to match rope diameter) bollards? Most climbing ropes aren't ridiculously hard like the rollgliss stuff and the wrench came of age on normal climb lines. Perhaps the rope pinch section might also be sensitive to having flatter surfaces pinching a very hard rope. Or small pinch points like a small pin. I once built a pinch/squeeze device similar application like the hitch hiker but it had profiled jaws and grabbed about 2" of line the idea being to distribute the beating up of the line and bollard faces. It worked but was a bit clunky and making it fine tune-able for line size kind of killed it (complexity). Or else just size it for one line - not general enough. (Actually, my son and I did sort of descent races on it going near free fall to pretty hard stop, the confidence coming from the big braking surfaces) So, formed contact surfaces may offer promise. Just look at GriGri's, ID's etc they're all profiled. There could be a rollgliss rope solution. Maybe?
 
My bollard is cylindrical but I am intrigued by Surveyor's newer elongated bollard that he tried. I may alter my miniBone to the long bollard and see how that works. I have not given up on SRT on smaller rope. It is so much lighter for hiking any distance, to use this smaller line, combined with smaller carabiners like they sell now, a smaller Bone, and other weight-saving measures. But that said, for regular climbs, I do love my poison ivy and full size original Bone.
 
If I can find the time and initiative I have a perhaps unique opportunity to make/test on the hard rollgliss line and the floppy DMM hook Reep-shnur(?) line that are similar sizes but at each end of characteristics. A tiny mechanical preferably without teeth and no rope bend would be cool for the hook. Cake and eat it too.... :-) The wrench generating pilot force for a pinch is the core of a few devices.
 
climbstihl said:
Any 8mm should work, you're putting a stopper knot under it anyway.
Click to expand...
This is true.
But I would be concerned with the life support effectiveness of a hitch/prusik when it has bottomed out on a stopper knot. My brain thinks the knot would cause the hitch the fail somehow, because it is being bunched up from the bottom.
Does anyone else see this as a concern?
 
Brocky said:
I wouldn’t think it could come off the rope, they won’t even slide very far onto a splice.
Click to expand...
Agreed, but a splice is different than a knot, a splice would just tighten a hitch from the inside out.
Does anyone have stats or physics of a prusik or hitch bottomed out on a stopper knot?
 
samsquatch said:
Agreed, but a splice is different than a knot, a splice would just tighten a hitch from the inside out.
Does anyone have stats or physics of a prusik or hitch bottomed out on a stopper knot?
Click to expand...
As long as the hitch cord is rated, I wouldn't be worried about it. I don't think any forces that you could generate could break it. You might be able to find some break tests of fruction hitches with stopper knots on @yoyoman s Youtube channel.
 
samsquatch said:
I'm wrestling with a Rollgliss ascender device right now. I want to be able to descend on it if an ascent goes awry. Funny thing is the RG is meant to be a descender, but once you chuck a drill in it to ascend, there is no easy way to descend. At least, when I reverse the drill, something is making a god aweful mechanical noise. I can't determine if it's the drill clutch or the RG's gearbox but something doesn't like powered reverse with gravity...
Cheers
Click to expand...


I've got a rollgliss as well. I've used this https://www.treestuff.com/store/catalog.asp?item=6887 above the rollgliss with moving rope system run through it. The rollgliss pushes the friction hitch up on a ascent, unclip from the ascender to descend on your climbing system
 
samsquatch said:
This is true.
But I would be concerned with the life support effectiveness of a hitch/prusik when it has bottomed out on a stopper knot. My brain thinks the knot would cause the hitch the fail somehow, because it is being bunched up from the bottom.
Does anyone else see this as a concern?
Click to expand...

If you're moving that quickly on a line that you generate enough force to break a hitch cord on a stopper knot you have other things to worry about, just the dynamic force of hitting the stopper knot without the hitch failing would break you in half.
-AJ
 
samsquatch said:
Agreed, but a splice is different than a knot, a splice would just tighten a hitch from the inside out.
Does anyone have stats or physics of a prusik or hitch bottomed out on a stopper knot?
Click to expand...
The hitch can’t expand enough being weighted to somehow slid over the stopper if you’re referring to that possibility, rather than breaking.
 
climbstihl said:
As long as the hitch cord is rated, I wouldn't be worried about it. I don't think any forces that you could generate could break it. You might be able to find some break tests of fruction hitches with stopper knots on @yoyoman s Youtube channel.
Click to expand...
moss said:
If you're moving that quickly on a line that you generate enough force to break a hitch cord on a stopper knot you have other things to worry about, just the dynamic force of hitting the stopper knot without the hitch failing would break you in half.
-AJ
Click to expand...
You're misunderstanding my concern, I'm not talking about breaking the hitch cord -- that dynamic would be no different with the hitch engaged on it's own or if it's against a stopper knot.

They dynamic I'm referring to is locking a hitch against a stopper knot from the bottom and loading the hitch with climbing forces... doesn't anyone else out there feel that a stopper knot would cause the hitch to spill itself in an unpredictable way? I'm hoping @*useless info* may have some thoughts here, just hoping I can follow along with them ;)

Cheers
 
Something would break first before a hitch could deform enough to fail, or it might force the stopper to untie first. The hitch is a closed system being tightly squeezed by the climber’s weight. The hitch is also being loaded from the bottom so the top wouldn’t be trying to be forced over itself.
It’s easily tested with a solid anchor and vehicle, for concrete confirmation.
 
[
samsquatch said:
They dynamic I'm referring to is locking a hitch against a stopper knot from the bottom and loading the hitch with climbing forces... doesn't anyone else out there feel that a stopper knot would cause the hitch to spill itself in an unpredictable way? I'm hoping @*useless info* may have some thoughts here, just hoping I can follow along with them ;)

Cheers
Click to expand...

I’m not following what you’re saying. If a hitch locks down on a stopper it can’t spill itself, it just stops at the stopper.

I must not be getting it, can you draw a rough diagram of what you mean?
-AJ
 
I've always noted that the tending pulley with it's fixed opening is the first contact with a stopper knot so the knot wedges in the pulley. Without the pulley I can envision a knot worming somewhat through VT braids at least. Then some doubt might set in. The loop on an XT would stop more positively but a pure coils section like the hitch hiker knot might behave in an unknown way - if without a tending pulley.
 
Bart_ said:
I've always noted that the tending pulley with it's fixed opening is the first contact with a stopper knot so the knot wedges in the pulley. Without the pulley I can envision a knot worming somewhat through VT braids at least. Then some doubt might set in. The loop on an XT would stop more positively but a pure coils section like the hitch hiker knot might behave in an unknown way - if without a tending pulley.
Click to expand...

Just for reference on real-world hitch behavior... a long time ago I worked too long in a tree without water on a very hot/humid day. At a certain point I realized I was in trouble with dehydration and needed to get the hell out of the tree. This was in the DdRT days, I was on a 150' line and needed to re-pitch to get out of the tree. I was so bad off, I didn't think I was capable of re-pitching or had the time. I decided to go as far as I could down the rope. I reached just above my stopper knot and my feet were still 6' or so from the ground. I took out the stopper and thought I'd pull the hitch like a parachute rip cord and slide off the end of the rope. Nope. I had a few wraps of vinyl tape on the end of the rope, it caught in the coils of the hitch, probably an XT but it could've been a VT, could've been a Blake's, doesn't matter. I was stuck, the hitch grabbed hard and I couldn't force the end of the rope through the hitch. I was able after 3 or 4 tries to lift my self up with my arms, hold with one arm and unclip my carabiner from the harness and drop to the ground. Based on that experience I don't believe it's possible to force a stopper knot through a hitch you've been using for life support, I don't care what kind of hitch it is, no way.
-AJ
 
Still use the Distel. It's just so easy and reliable. Sometimes the only adustment I need to make is which way it's facing (the hitch doesn't care, but sometimes it just grabs a little better one way or the other) or maybe adding a little twist to one or both legs before clipping it in. Just little bitty adjustments and it's all good.

But, there are hitches that tend a lot easier, like the VT and variations. Too finicky, though. Sometimes somebody posts a hitch on here and I try it on a couple of systems and think, "Hey, this is sweet... I'm going to try this out, tomorrow!" and I even write myself a note. The note is immediately sucked into some cosmic vortex and ends up... well, that mystical place that a clothes dryer sends the occasional odd sock. I then promptly forget all about the cool hitch and tie a Distel the next day.
 
You must log in or register to reply here.

New threads New posts

Back
Top Bottom