Can you prusik double ropes?
HTML-код
- Опубликовано: 12 май 2023
- Having a prusik around 2 ropes can be for a handful on contexts, but this was looking through the view point of a SAR (Search and Rescue) lens. This was part of more testing that day and you can see "Can you evenly tension two ropes?" at • Can you get Twin Tensi... . Thank you Matt O'Donnell for visiting the lab and doing this with us.
👉 Learn and SHOP at www.hownot2.com/shop
👉 Best EMAILS on Earth: www.hownot2.com/signup
👉 SUPPORT US and get gear discounts hownot2.com/support
👉 10% off ROCKY TALKIE by clicking www.hownot2.com/rocky
CLIPS video complementing this video of other tests we did that afternoon - "Can you get Twin Tension rescue ropes evenly tensioned" ruclips.net/video/H0M6F16vWTA/видео.html
Check out our new store! hownot2.store/
why was that video on the clips channel? I thought that one was very cool and interesting, and somewhat different
I've always used a Prusik on two strands below my repel device when repelling. So this was pretty cool to see.
In that case, the prusik is basically only ever going to hold enough force to keep the brake strand in position, which would be much less than 1kN.
@@Govanification This. Unless your rapel/belay device is suffering catastrophic failure.
Its just a backup❤ its good protocol
@@Mike-oz4cv prussik is good normally for failure but not if you secure only one rope in the ATC on a double rope rappel, I used to test it on ground and the prussik was grabbing only the secured rope and the free rope was going up while simply walking back, would have been a big crazy fall. We must always test the system on top and not thinking everything will be ok cause we use a prussik.
@@pascaljutras178 Just thinking about unlikely scenarios here. For example the ATC carabiner accidentally opening and unclipping itself. In that case it’s nice to know that a prusik is plenty good enough to hold you.
Footlocking a doubled rope with a prusik or klemheist has long been a standard method for arborists ascending trees. It’s fascinating to see these systems tested
For a long time!
Not like this - what arborists called 'double rope' (now 'moving rope system') is a rope fixed to their harness, over a branch, back to their harness. One end is fixed to their harness and one end is prussiked to their harness. The prussik sits on one leg of rope.
This channel has some of the most absolutely useful and IMPORTANT information I've found online. As a climber for over fifty years and instructor for more than forty, I'm delighted to still be learning from you guys! 🙏
I'm just into rigging and find this channel to be the best at examining this subject too. 👍
Former rock climber turned firefighter. I love this and and the other rescue videos you have done!
I'm a mountain climber and arborist, Ryan and Bobby thank you for answering every question I have ever had about gear's ability and many more I could never have thought of. In all my experience it's the pink naked upright walking monkey dangling from the gear thats ALWAYS the weak link! Yes even me! If there is enough interest from the community I should like to volunteer to be tested on the slack snap machine. lol
Please carry on break-in gear fear
Like it. Using prussics as backup for descending on double ropes. Until recently only 2 turns. Now I am using 3
Enjoyed the content. Am a arborist and Firefighter and watch a lot of your stuff because eventually it crosses over and I find things that are applicable to our profession.
Good stuff
As a retired?? climber, in other words the spirit is willing but the flesh is weak, this fascinating. I used to sew my own gear and had a friend at GA TECH materials science lab who would test a sample for me but this way way better. Super good enough.
Great to see this test, thanks HowNOT2
Love it. Thanks for going the extra effort in testing.
Loving it. Thanks for all the knowledge.
Love it! Can’t believe it took me this long to find you!! Keep it coming!
Definitely want more rescue gear content. Thank you so much for all you do.
Thats some jolly good content right there
Loved this! You guys have such great set-ups for testing, I will always watch these videos.
Love any testing 👍🏼👍🏼
Nice! Yes. As always, great stuff ryan. Keep pushing
Awesome. So much value for rope users.
Fantastic content! I really appreciate these kinds of videos, as they are very relevant to my climbing practices. Thanks!
Arborists use something called a foot locking Prusik. And that is meant to go around two strands
I really like this sort of content. The rope rescue world is full of practices that are based on tradition and we are not sure what they would actually fail at. 8mm prussiks on 11mm and 12.5mm ropes have been tested to death, and their behavior and peak forces are all over the map.
Yes! Lots more of this, please! As someone who works on a rope rescue team, this stuff is fascinating!
This is the kind of content I like as a patron!
I like all of your content but I love the rescue content!
Love the videos as a saddle hunter I appreciate the variety of information you put out.
Awesome content. As an engineering student, I am always excited to see your videos and ponder why these results happen. Thanks for the videos.
a very practical and awesome experiment 👍
Appreciate the content 🤙
I've had the question of prusik on single vs double rope for a while now. Been using it but good to see it pushed to the limits without people on the other end. Good video!
Awesome learning new stuff about two rope repel.
Thx
As an arborist, I really love that !!!! Thanks
definitely interested in videos like this. I always thought from personal experience ascending ropes with prusik knots that 2 ropes would have better grab than 1 so it's good to see that confirmed
Great video!
Thank you so much for the work you are doing!
I appreciate the videos on knots , their strength, and the way they fail!
Please test and review the JRB ascender hitch !
I love seeing the limits and modes of failure on the gear. Seeing what it takes to get gear to fail, and having realistic ideas about actual operational loads and forces is priceless!
Love your work! Please keep it up!❤
Yes yes yes!! Want more of this.
Great video! I'd like to see the hollow block put through several rope configurations or different diameter accessory chords tested too
This is what I come to this channel for! I love the nerdy stuff.
Love this kinda stuff!
Epic safety services rope content!!
Just leaving a comment to help with the algorithm. Thank Ryan for all you do.
I was looking up this very thing the other day and didn’t get the warm and fuzzy from my research, but now I have the data to back it up!
Liked it. Great video!
This was great, thanks
68,000 views in 10 months. Well on the way to 100k. Most excellent channel.
Just the video I need today. What a coincidence!
Love these videos. I do rope rescue and confined space, and seeing how everything works and fails is allowing me to adapt to different methods and equipment I would have otherwise never considered.
The problem is that after you watch the Palikoa Pivot break half the gear he tried to break it with, you start wondering how to build a chain out of them.
ruclips.net/video/l8VvEWdDMus/видео.html
As an engineer and climber this content is great!! I've always used a prusik under my rappel device and for emergency ascents on double ropes, so this is very interesting. It would also be helpful to see other autoblocking knots for comparison!
Awesome
Just the type of RUclips I like
Hell yeah I like it!! The way I see it is _Content is Content_ and I'm just happy to get it. 👍👍
I like this content!
I love the content focused on fire and rescue.
It's good to see that this works OK, since I definitely used it before in a pinch to ascend a doubled rope to rig/derig some circus aerial apparatuses on a portable rig when I didn't have a ladder handy!
I’m happy to see this video Ryan. It’s common practice in Rope Rescue for a litter attendant to put a prusik around both main lines just above the yoke knot of the little bridle, and then have that be their primary attachment point to give a little extra space for litter attendant movement. The speculation was that it might not hold properly. This proves that holding power is not an issue. The only other concern is when using, a freestanding artificial high directional, like an Arizona Vortx in the easel leg configuration. If the rescuer has set that prusik two or 3 feet above the yoke knot, it can run into the high directional pulley and quickly change the force resultant creating an instability. It’s just a concern to watch out for and I think that this test shows that a single prusik works well attached to two main lines.
I would love to see more rescue stuff. Maybe breaking rescue pullyes or figure 8s or even full z rigs. I got into climbing through firefighting and the military and would love to see that stuff. A swiss seat would be cool too
Sort of akin to using an undersized friction hitch for the rope diameter. Tree work is generally -3mm, ie use a 10mm hitch cord on a 13mm rope, 8mm on 11mm rope. This makes the rope effectively larger. I assume you can lock up these hitches to point where you can't loose them by hand.
Cool video!
Loved it
I used a prusik on a double rope as a safety line the last few days going up and down a 30 foot ladder trimming an oak tree. The prusik is about the same size rope as the safety line, only required 2 wraps of the prusik to have enough friction.
A fascinating examination of this knots characteristics under load. It fails very gracefully all things considered on a single line with the slipping. It's wild how it got hot enough to start melting like that! Great video! Can you do one for the trumpet knot? (Designed to tie out a bad or worn section in a rope without cutting it.) I know that isn't really a climbing knot per se but it is kind of unusual and maybe interesting to see like this. Great stuff. 👍
That’s a great shirt idea, if not already in play. Heart beat of a Prusik
This is why testing is so important. Even with decades of rope experience I was sure that the prusik would grab tighter on a single strand than a double. Thank you HowNOT2. Can you compare the larks head to the prusik to the prusik^3 to the prusik^4 please (i.e. how each additional or fewer wraps changes the grip.)
I’m surprised that you were surprised! From your video on the VT prison and other friction knots I vaguely recalled that the ratio of rope to rope determined grippiness. E.g. 8mm Prusic won’t grab on 9mm half rope. But fat dual 13s it would grab really hard. And did.
I would love to see prussiks of different material or other hitches. Great videos!
Looking forward for you to test a Blake's Hitch. I'd really like to see that, since I've been counting on it for years lol.
love it
Today I asked Google if friction hitches on double ropes were effective, and it turns out you posted a video about it 2 weeks ago! I actually rigged up a little test of my own before looking online, but it always feels better to see the numbers.
I did some spelunking with prussiks because I didn't have more appropriate ascenders.
Perhaps a bit more muddy than the rope in this test, but worked. IIRC, 6mm cord on 11mm rope.
Prussiks are taught as self rescue or backup methods.
Very helpful video, please make more friction hitch testing, maybe autoblock or Klemheist?
Very pleased it works to prusik on both because I've climbed up ropes like that and good to know I haven't died and didn't realise ;) Also I've used French prusik (auto block) above my descender (passing knots is easier that way, I know people will reply it is "wrong") on doubled ropes for retrievable abseil (rappel) and that grabs really well - better than on a single rope
Tom Tom, I've always done the same thing and its always worked great. I'm just some old guy in the mountains with minimal gear, double rope fits my needs often.
Love this I find it crazy that they use it for 10 plus years I'm on sar in Alberta Canada and we have to retire after 5 if it's been used and it has a ten year shelf life if never used but crazy how's much force it still takes
Very interesting
Looking at the behaviour of the prusik on the doubled rope, physically it looks like the paired rope is squashed to be virtually a single larger diameter rope - changing the prusik cord diameter to host rope diameter ratio. It would be interesting to see if you get the same result with the same size prusik cord on a larger diameter rope.
Thank you for sharing your great experiment.
I would like to see if the prusik would still work if one of the two ropes breaks.
I Like this
I had this exact question when using a prussik as a third hand on a two rope rappel
Would like to see other versions of the prusik. VT, french, autoblock etc.
I like it :)
This result would indicate that the defining factor of a prusik is the ratio of the prusik cord diameter to the net diameter of the line it is attached to. In the case of the double rope, the effective diameter should be about 1.5 times the rope diameter, which would indicate a higher grip and less slip. Which is what you saw.
A neat test would be to try a prusik on a thin rope (like 8.5mm), then double the thin cord, and then try a single larger rope (13mm) and see if the force to start slipping is the same.
I’ve always done that!!
"That's the heartbeat of a prusik!" Ha! Ryan's got jokes! =-D
This is a great vid Ryan, is there any new bobby tshirts coming out?
Like it!
Throw a rope over a tree and prusik up. Easiest way to get up there.
Also I learned that the prusik grabs better the bigger the difference in diameter between the sling and the main rope is so that's probably why double rope grabs better.
TIL that prusik on two ropes ends up having more friction than a single. But I guess that makes sense in that two ropes will have more surface area than a single.
This is good stuff, not everything is about the breaking point, it's about the failure point, and those two things aren't always the same.
Awsome
I would be curious to see different mantle materials and weaves compared. Would be nice to know if there was a combination that could slip at a given load to prevent overloading equipment and or act as an indicator.
i liked it
I used to work at an outdoor centre where we used steel eye carabiners to clip into harnesses. To start with we used rethreaded figure 8's to tie into the eye carabiners but we eventually switched to using Bowline on a bight (we used s stopper knot on the tail for both knots). I'm trying to remember why we did this and thinking that the Bowline on a bight might have been stronger, but I can't find the breaking stats for the bowline on a bight in climbing rope. Would you be able to do an episode for figure 8 vs Bowline on a bight, please? Thanks 😊👍
Now that's some results 8:34
Awesome video! due to my long-ago NCRC cave rescue training including vertical rescue, I am familiar with using prussiks for haul-system brakes, safety catches and haul line ratchets. I also have used prussiks for ascending in vertical caves and related training. I was gratified to see things behave in your tests as I expected based on my training, education and experience, namely the greater the size difference between the prussik and the main/haul line, the higher the the loop's gripping force before the loop slips and releases some energy. The double rope main line tests behaved as I expected, i.e. behaved as a larger single rope.
Possible future testing - how does a double main line behave with respect to the prussik if one strand is dynamic rope and one is static rope? If the two ropes are notably different sizes (e.g. 8mm & 11mm)? In a minimal gear self rescue situation, will prussiks cut from main line rope grip a doubled main line? Thanks!
great video, what if you pulled each rope in different directions?
I often use prusiks on double ropes. Well, i use schwabisch knots. The capability of double ropes is why i often use friction knots instead of mechanical ascenders. If you get your ropes stuck on the pull after a rap, you want to grab both ropes on the ascent. Only a few mechanical rope clamps will do that. EDIT 3 days later: lest I forget, I really, really appreciate you doing this stuff... so I don't have to worry as much. And you are funny.
Buy an alpine Up from Climb tech
The talk about the basket and the train sounded new, I haven't heard those terms before. If it isn't a series of rappelers coming down one after another, then I don't know what it is. I learn an awful lot on this channel beyond what my outdoor recreation degree taught me.
In the fire service, a medical patient is strapped into a "basket" in rope rescue situations to pull them out of a bad spot, and put them in a vehicle. Depending on the situation, firefighters can clip into the basket, maybe that's what he means by train
He was talking about terrain. When using a basket to evac a pt the rescuer has to keep the basket away from the rock face. The basket will some time catch and then the system goes from moving to static rapidly increasing the forces on it. Usually you would use your feet ant legs to push away from the rock. The basket and rescuer is lifted with a mechanical advantage system in the rope. The prussik is used as a grab to connect the MA to the ropes.
I think the train is actually the team of people pulling the rope, from up near the anchor
Ya know. This make me feel a lot better about my third hand. Do things right and the safety is there.
Would be interested to see the tests on smaller ropes, i.e. lead climbing sizes like 8.6 or even smaller.
Would some kind of a friction knot be a good idea to join to end ropes?
Creating a bite on one end and wrapping a friction know around with other, keeping all system pretty much in line without sharp bend? Would it be stronger than other ways to of joining two ropes?
Would love to see the vt prusik tested
Interesting to see sling prussic around four strands as used in escaping the system when belay is entirely rope built.