Climbing tips: How to tie a Purcell-Prusik loop (Personal anchor system)
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- Опубліковано 4 жов 2024
- The Purcell-Prusik can be used as a personal anchor tether or in emergency situations an ascender. The Prusik knot will slip under load, absorbing some energy in a fall situation.
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You explained everything perfectly! Thank you for all the details! I've subbed a long time ago. Liked etc. Detail in tying is excellent! Cheers from Australia 🙂👍👍👍
Dude this a great option for a Personal anchor, thank you very much! the only observation is as you realized this is a "mini" anchor, I would recommend least 3 meters of rope!! but still, a great option, I´m going to have one of these myself for climbing!
Good video, perhaps it would be easier to finish if the double fisherman's knot was done after the prusik knot to make passing the rope through the loops. Just a thought.
Good point, and an added benefit to that approach is that the rope would not twist that way, making for a more manegable process & neater looking finished product.
Another consideration is when passing the accessory cord through the coil of the prusic is to use a hollow tube which is slid into the coil as your finger is simultaneously pulled out of the other end. The cord is then passed through that tube, & tube removed together with the accessory cord as it reaches the end of the prusic. That way the accessory cord can easily be passed through the prusic without the coil “falling apart” in the process.
Thank you.... Yet another valuable idea...
a nice technique to set up the prussik at 53sec
Good day. Very much enjoy your videos. Similar to a chained system, would it would be safe to use the prusik loop section above the knot as a shelf to hang gear and the like? In my desktop laboratory tests, attaching a carabineer above the knot appears to load the prusik knot nicely and assist it with jamming. That being said, would appreciate any insights you may have prior to exploring this in a real life scenario a number of meters off the ground.
Cheers!
re 2:40 much easier to first tuck a bite (next to the grapevine), to stabilize the prusik, then work the grapevine thru (only if necessary).
My preference is (at 1:00) to put the grapevine at the bar of the prusik (behind your middle fingers), which makes it easier to tie & handle (especially with gloves), and the rest of the system is much cleaner, since you don't need to tuck or adjust the bulky grapevine.
re 5:44 This part is badly demonstrated in that he did not show how to properly 'set' the prusik, essential to avoid sudden limited but uncontrolled displacement (extension) of your anchor during a fall.
It seems to me this is a potentially lethal method. Here is why. Prussics and similar friction knots are typically used for rope assent, personal backup on an abseil and various rescue setups. All these scenarios typically don't experience high loading, whereas a main belay has to be suitable for a fall factor 2. As you said the knot slips, rope slipping on rope generates heat. The unknown factor is how much heat. It is pretty obvious that heat not only melts a rope, but prior to melting reduces its strength considerably.
PERSONAL anchor. Not, main belay anchor.
Far easier to just tie the prusik around your hand, and then pass the tail through.
A Prusik is really only truly useable if you are in need of a loop that can neither close or open. Things like Klemheist or other friction knots are much easier to tie if youre only pulling in one direction.
So you're saying the prusik is good for this application?
It depends on what you want to do...if you are only pulling in one direction...like ascending or descending a rope..or a horizontal pull in one direction...other friction hitches are easier to use...a Prusik really locks up...so if you want that feature of a really solid hitch and dont want it to slip in either direction...yeah go with it...
I may just be inexperienced but at this step I only trust a regular 4 wrap prussik, the fancy one direction once’s scare me because they can become so loose with a pulley.
you did it the hardcway.
do you know any easier way?? can you show me please?
Cool. Now I have another use for my 12 footer cordelette. Right now it is the trusty foot loop cheater.
I dropped it about 6 times
Would this work on 8 mm
Yes, it would just take more length and of course would be bulkier. If you're using this as a PAS you're probably fine with just 6mm since you shouldn't be taking very big falls on it. Most Personal Anchors are not guaranteed to hold above a factor 1 fall (that means they won't hold you if you fall from above where the personal anchor is clipped in). And even if you fall from below that clip-in point you could still hurt yourself.
TLDR: 8mm is a bit thick unless you're in industrial work. 6mm is fine, but try not to take falls on your PAS
Just a question maybe a dumb one but whats the great advantage to the double fish as opposed to the simple double square. Love the double fish just wondering the mechanics behind them.....
The double fishermans is far less likley to fail under extreme load. Double sqaures are strong but can't take as many kilonewtons as a good fishermans with long tails.
I just made this using 10 mm double braided type. The prusik knot slips.
You cant use line that large...prussiks are designed to be made usung accessory cord anchored to a larger rope.
@@johnrobertson7583 yes, exactly! the difference of width is what creates more friction, therefore locks the knot!
You’re dead twice! If you use this technique for tree climbing always pretighten your friction knot before loading you weight into it. I use a 4!!! Wrap prusik as repel backup and it absolutely failed at near free fall speed (I noticed I not working and descended) as fast as I could to test if it would ever work
I 100% agree that friction hitches need to be preloaded but no one died in this hypothetical test. Even if the prussik fully slips you're still only going to fall about a foot.
Kinda kool . Basically its just a poor mans adjustable lanyard... Not really worry free, just in set it an forget it, not in total failure at all.