# Does a prussik have to be thinner than the rope its round?



## DeanBrown3D (Aug 3, 2006)

Because I think I read that once but I can't see it anywhere now. I was only wondering because I see prussik cords between 3/8 and 5/8" diameter for use on typical climbing ropes. Any suggestions?

Thanks

Dean


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## Stumper (Aug 3, 2006)

Smaller than the host line is usually recommended...but it doesn't have to be. We commonly use friction hitches tied with the rope's tail and they work(same diameter, material and construction). Using 3 strand hitch cord on 16 strand braid give some interesting results and willl actually work with a hitch cord larger than the host line.


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## a_lopa (Aug 3, 2006)

technicallly yes.


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## Del_ (Aug 3, 2006)

A closed prussik works better than an open one.


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## DeanBrown3D (Aug 3, 2006)

Ok thanks for the advice. I've been trying some knots, and it seems the 3-strand is just as good at gripping as the braided. 

What are people's preferences here (for the _prussik loop_, on a braided flip line), apart from being cheaper for the 3-strand?

ps TreeCo what's the difference, open or closed?


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## Del_ (Aug 3, 2006)

DeanBrown3D said:


> ps TreeCo what's the difference, open or closed?



In the traditional arborist rope climbing system the prussik is open.

A loop would make a closed prussik.

An open prussik only pulls on one side of the knot and a closed(loop) pulls on both sides. Pulling on both sides locks up and breaks easier.


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## TheTreeSpyder (Aug 3, 2006)

A smaller diameter rope of the same material and construction will bend/mate around the host full size line better. This gives better grip and less strength loss to the smaller diameter 'cord'. Bending a line around itself may work for grip if line is flexible enough; but the strength loss will be much greater than a smaller diameter cord bent around the 1/2" etc. (rope) device.

i experimented for awhile with a 5/8" 3 strand as a split tail for a Blake's around 1/2" lifeline as 'host'. It can be done, but not recommended; the smaller diameter seats and grabs so much surer and quicker.

i prefer 3/8" Tenex around a 1/2" lifeline; it flattens to not grab as intensely on single narrow line like round cord; and in flattening it grips better and with less strength loss.

Real stiff cord, even of the same diameter might not grip as well, and surer; higher strength loss.

The friction hitch / prusiks that gives support from 2 legs of line from friction hitch gives better grab and better release/ redress as Dan-o says. There is less tension per line of support; to grab at least as well and free up easier. Also, the 2 (rather than 1 leg Tautline / Blake's as single leg of support friction hitches) legs of support in the prusiks by halving/ sharing tension between 2 legs in the prussik allows the smaller diameter (therefore less tensile strength generally) to be safe as a single leg of support in larger diameter/ tensile.

These prusiks are for experienced peoples ascending in 1:1 SRT; but not descending. Pros can Ascend/ Descend in the standard 2:1 support of a tree climber's DdRT safely because the bodyweight can shift over to leg of line terminating at saddle and allow the other leg of support to 'stretch' ie. free up friction hitch to slide easily. In SRT there is no other line of body support to switch climber as load over on to. More static line can be used in SRT, than DdRT for same shock absorbing capability; due to elasticity % is different / higher for more weight on the single line; than each leg of the DdRT.

Sorry:taped: 

LOts of knots, knot research and science; friction hitches etc


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## Bermie (Aug 5, 2006)

DeanBrown3D said:


> ps TreeCo what's the difference, open or closed?



Open= one end of the friction hitch connected to your 'krab' the other end loose with a stopper knot - Blake's, Tautline.
Closed= both ends of the friction hitch connected to your 'krab' - Prussik, Distel.


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## DeanBrown3D (Aug 5, 2006)

Ok, but how can a prussik be open?


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## woodchux (Aug 5, 2006)

DeanBrown3D said:


> Ok, but how can a prussik be open?




An open prussic is tied with a stopper knot.
A closed prussic is tied with a loop of rope.


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## DeanBrown3D (Aug 5, 2006)

Oh I see. Thanks for the cool pics!

Does the open prussik grip in both directions?


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## Ax-man (Aug 6, 2006)

To answer your question, yes, it should grip both ways if properly tied, dressed and set. 

An open Prussik is better suited for a traditional climbing line friction hitch set-up, your asking about a flipline or lanyard, a closed prussik would work better. I have never heard of anyone using an open Prussik on a lanyard, not saying it wouldn't work though. 

Personally I have never been a fan of the four or six coil Prussic closed or otherwise for any climbing knot application, they lock down too hard and are hard to break to get them to release, a Knut or a French Prussik would work much better for a lanyard. 

Larry


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## jmack (Aug 6, 2006)

TheTreeSpyder said:


> A smaller diameter rope of the same material and construction will bend/mate around the host full size line better. This gives better grip and less strength loss to the smaller diameter 'cord'. Bending a line around itself may work for grip if line is flexible enough; but the strength loss will be much greater than a smaller diameter cord bent around the 1/2" etc. (rope) device.
> 
> i experimented for awhile with a 5/8" 3 strand as a split tail for a Blake's around 1/2" lifeline as 'host'. It can be done, but not recommended; the smaller diameter seats and grabs so much surer and quicker.
> 
> ...


 Unrelated thankyou fer the link ts


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## TheTreeSpyder (Aug 6, 2006)

YW!

i think thee is a place for a standard prussik's grabbing in either direction in a 2 way lanyard. But, other than that and speed of double/triple choking a loop for utility functions; agree that our more evolved/specialized friction hitches suite our purposes best.


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## DeanBrown3D (Aug 6, 2006)

For me, from the knots I have learned so far, the blake's is seemingly the best one, it seems to never fail and I have managed to get a prussik to slip some times. Must be not set right I guess. Seems to me that a blake's would be a good choice for a lanyard knot.


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## Del_ (Aug 6, 2006)

DeanBrown3D said:


> For me, from the knots I have learned so far, the blake's is seemingly the best one, it seems to never fail and I have managed to get a prussik to slip some times. Must be not set right I guess. Seems to me that a blake's would be a good choice for a lanyard knot.



The blakes is not a good choice for a lanyard knot mostly because it is an open knot.

Dan


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## moss (Aug 6, 2006)

TreeCo said:


> The blakes is not a good choice for a lanyard knot mostly because it is an open knot.
> 
> Dan



DeanBrown3D can have his cake and eat it by using the Martin, a closed version of the Blake's.
It's on page 4 of the pdf:
Son of a Hitch: Geneology of Arborist Climbing Hitches


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## Ax-man (Aug 6, 2006)

Another pretty much failsafe knot on a lanyard is the Distel, a closed tautline. 

One of the guys that works for me is getting into climbing. I don't have much in the way of spare gear and hardware to get him a first class set-up. We finally got him a good saddle, I set him up with a rope lanyard with a Distel, it was OK but he soon wanted something that worked easier. Changed the knot to a Knut and a dog snap as a slack tender, he used it yesterday and was a very happy camper, said it was a much smoother on the release and taking up slack. 

All this is my fault though, last year we didn't have a spare saddle and he wanted to trim a small easy Maple tree. I let him use my saddle with the DEDA set-up with all the bells and whistles, he took to that like bees to honey. I kind of spoiled him with that set-up.


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## TheTreeSpyder (Aug 7, 2006)

This is a comparison i maid of self tending friction hitches awhile back.

The Distel; and it's brother with the turn that sits alone at the bottom reversed (Schwab) fit about the same pattern, except only buffer the loading to 1 (top)leg going to the main coil. (Naming a Turn as 1 turn, RoundTurn as 2, Dbl.RoundTurn as 3 and Coil as 4 uninterrupted turns).

Presently have evolved in the last pictured friction hitch to tuck the final leg (yellow) thru the choke of the other leg/coil bottom to make more of a proper backhand hitch. This works very well for me, including self tending characteristics.


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## John Paul Sanborn (Aug 8, 2006)

I like a VT on some cheap double braid like 3/8 stable braid. you can buy it bulk for around $.40/ft.

the smaller the tress cord the mor friction heat will develop though. So fast decents can melt the cord.


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## Ax-man (Aug 8, 2006)

I agree, that has been the best cord for a VT of the all the ones I have tried so far. It slips a little when it is new, but once it gets broke in it grabs on cue and releases easily and doesn't seem to gather as much heat on a desent like the other cords.

The trouble is finding the stuff, there is only place that I know of that has it, we both probaly got it from the same place and they don't always have it in stock. 

Larry


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## teacherman (Dec 15, 2022)

Ax-man said:


> To answer your question, yes, it should grip both ways if properly tied, dressed and set.
> 
> An open Prussik is better suited for a traditional climbing line friction hitch set-up, your asking about a flipline or lanyard, a closed prussik would work better. I have never heard of anyone using an open Prussik on a lanyard, not saying it wouldn't work though.
> 
> ...


I'm going to look up some pictures of an open prussik. I use a three coil regular closed one for my lanyard, as I won't use a lanyard that works only in one direction. I am trying to let go of the idea that it has to be symmetrical to work well bidirectionally.


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## TheJollyLogger (Dec 15, 2022)

teacherman said:


> I'm going to look up some pictures of an open prussik. I use a three coil regular closed one for my lanyard, as I won't use a lanyard that works only in one direction. I am trying to let go of the idea that it has to be symmetrical to work well bidirectionally.


This is an 18 year old thread, the industry has changed a lot since then.


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## teacherman (Dec 15, 2022)

TheJollyLogger said:


> This is an 18 year old thread, the industry has changed a lot since then.


Well, no question about that. This thread popped up on a google search, and I haven't been on here in a while. I'm just starting to learn SRT, and at my age, I move so slowly that it'll take me forever to try out every variant.


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## TheTreeSpyder (Dec 21, 2022)

Does a prussik have to be thinner than the rope its around?
>>IF is closed friction hitch of 2 legs of loaded support to saddle as Prussic,
not so much single loaded leg 'open' friction hitch such as Blake's/Proh-grip.
.






.
Blake's real and faux(foe) 'sui-slide':




.
A> When working with rigid objects of wood, metal etc., the stiffer rigidity can displace/bite into lesser to lock.
B> Look at everything as displacement against another.
>>rope rigidity i look at as native rigidity xTension squeezed into such and such a dense footprint size/width.
2support legs gives half load rigidity to rope/cord, trying to displace into/against a full loaded rigidity.
>>We go with smaller, tighter, denser force packed into a smaller footprint rigidity,
>>to make up for the loss of tensioned rigidity that equal partners at different loaded rigidities would have.
So, then also, this means these factors can be tuned to suit, beyond just the mating interface beyond their textures, and and shared force involved.
.
Also note, on 'closed'/dual support legs a loop is more self adjusting, but terminal legs to saddle can load more to 1 leg than the other as another trade-off.


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