Author Topic: Best Gripping Hitch for Vertical Pole  (Read 39825 times)

dmacdd

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Re: Best Gripping Hitch for Vertical Pole
« Reply #15 on: July 27, 2010, 01:51:28 AM »
The Camel Hitch tied for a vertical pole is my new favorite.  Here is the loosened hitch:

It's not the knot that ABok 1741 calls the camel hitch.   That camel hitch has the lower hitches going the other way around the pole, similar to the (unhitched)
http://davidmdelaney.com/icicle-hitch/icicle-hitch.html



dmacdd

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Re: Best Gripping Hitch for Vertical Pole
« Reply #16 on: July 27, 2010, 04:00:23 AM »
OK, is there a common name for the hitch in my pic?

I don't know.  But it's a rolling hitch with two extra turns and one extra hitch.

Dan_Lehman

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Re: Best Gripping Hitch for Vertical Pole
« Reply #17 on: July 27, 2010, 05:10:14 AM »
The Camel Hitch tied for a vertical pole is my new favorite.  Here is the loosened hitch:

It's not the knot that ABok 1741 calls the camel hitch.   That camel hitch has the lower hitches going the other way around the pole, ...

OK, is there a common name for the hitch in my pic?

Brion Toss's Rigger's Apprentice has as the Camel Hitch your version, but
with fewer turns -- apparently he didn't notice the difference w/Ashley's.

Note that Ashley shows it pulled the opposite way but notes that
the intent is to hold in either direction; Toss seems to presume just
the opposite-way loading, and shows it as the knot of a noose-hitch.


Frankly, I'd dispense with the final Half-hitch (making the Clove) and
tie off with an Overhand stopper not instead -- MUCH more secure!

Or, finish the knot (at the point of this Clove hitch) with a Reverse Cow
hitch
-- i.e., turn the tail in the opposite direction,
come back around on the away side from the knot (making no Half-hitch),
and then turn around your tail and go around to bring the tail
out through this turn so that the turn/bight nips it against the
lead into this "Reverse Cow" finish.  The nipping is sure, and even
increased by loading the structure's SPart in the direction you show.

(To put this in other words, in this Cow finish, the tail will reach
to the away side of it and finish on the near side; were you putting
oh Half-hitches in the usual way, it would go near to away.  The
loaded part of this "Reverse Cow' will pinch the tail against the turn.)


--dl*
====
« Last Edit: July 27, 2010, 06:19:05 AM by Dan_Lehman »

Bob Thrun

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Re: Best Gripping Hitch for Vertical Pole
« Reply #18 on: July 27, 2010, 05:32:03 AM »

???  By which arborists?  -- not Mahk Adams, nor do any of the readily
accessible images match this.  As put verbally, the Distel "is like a 3:1
Clove -- AND both ends are loaded.  In this "Mason", it is not a Clove,
and only one end is loaded, with an interesting nip of the end
-- like a Reversed Ossel Hitch.

 :)

You are right.  It was not clear in the original drawing that only one end was loaded.  And I missed the way the final tick is done.

Dan_Lehman

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Re: Best Gripping Hitch for Vertical Pole
« Reply #19 on: July 27, 2010, 05:35:14 PM »
Nice image!   :)   Yes, that's it (simply described (simply altered one way or another)).
And I think that --esp. for tying to a pole, in contrast to some flexible object--
this structure is less secure under load --to it I'd finish with a stopper,
if not replacing the final Half-hitch with a stopper as said above.
(I don't trust the Clove h. to stay tied.)

Friction hitches can be tricky, and I have some skepticism about them,
in general.  So much seems to depend on materials (structure, fibre,
condition, shape, flexibility, relative sizes) and forces.  I recall using
a Hedden hitch in (I think) half-inch solid/flexible polyester (lubed!)
cable-hauling tape in which it held my weight initially, but on subsequent
attempts to stand on this it slid (!!?).  And recently in playing around
with the ProhGrip / Blake's Hitch, I found that I needed to slightly
extend the spiral of the rope coming into the knot in order for
it to grip and then grip harder w/higher load.  That said, I'll remark
that it seems a piece of common knowledge that with standard
materials of an 8mm? kernmantle rope tied in a Prusik hitch around
11-13mm kernmantle  slippage will occur at some high load.  (It's
of course possible that this "knowledge" arises from one reported
testing.  And in some cases of such testing where slippage is seen,
the testing is done on a slow-pull device that takes a while to build
up force on the slipped knot, but with actual use and some mass
making that load, there'd be no such reduction in force upon the
slippage --rather, some momentum of the load.)

Also, there isn't much presentation and research made for using some
combination of friction hitches -- e.g., a structure like what is
called the "Camel hitch" but in place of the Clove hitch there is
a Rolling hitch (or other friction hitch) and the load of course is
taken in the usual direction (for what I'll call "away-end" loading
-- that of the Rolling h., e.g.).  As shown in the OP, the loading
is to the "near-end" , as is the Klemheist & ProhGrip.


--dl*
====
« Last Edit: July 28, 2010, 04:34:37 PM by Dan_Lehman »

knot4u

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Re: Best Gripping Hitch for Vertical Pole
« Reply #20 on: July 27, 2010, 07:20:35 PM »
Frankly, I'd dispense with the final Half-hitch (making the Clove) and
tie off with an Overhand stopper not instead -- MUCH more secure!

Or, finish the knot (at the point of this Clove hitch) with a Reverse Cow
hitch
-- i.e., turn the tail in the opposite direction,
come back around on the away side from the knot (making no Half-hitch),
and then turn around your tail and go around to bring the tail
out through this turn so that the turn/bight nips it against the
lead into this "Reverse Cow" finish.  The nipping is sure, and even
increased by loading the structure's SPart in the direction you show.

EDIT:  The pic below is a hitch with the Overhand Stopper finish.  I took the liberty of naming them.  Yes, this hitch is quite secure. To prevent jamming and to make the overhand a little bigger, add a slip on the overhand.  For simplicity, there is no slip shown.

"Gripping Half Hitch"

« Last Edit: February 09, 2011, 08:16:31 PM by knot4u »

dmacdd

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Re: Best Gripping Hitch for Vertical Pole
« Reply #21 on: July 27, 2010, 11:28:18 PM »

Or, finish the knot (at the point of this Clove hitch) with a Reverse Cow
hitch
-- i.e., turn the tail in the opposite direction,
come back around on the away side from the knot (making no Half-hitch),
and then turn around your tail and go around to bring the tail
out through this turn so that the turn/bight nips it against the
lead into this "Reverse Cow" finish.  The nipping is sure, and even
increased by loading the structure's SPart in the direction you show.

I cannot follow this. I presume it is not this:

which would, I presume, be said in this context to be finished with an unreversed cow hitch.

DerekSmith

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Re: Best Gripping Hitch for Vertical Pole
« Reply #22 on: July 28, 2010, 09:23:11 AM »
Remember though, that all these hitches only work well when the cord diameter is significantly smaller than the pole.
Derek

Those hitches in your pics have overlapping loops on the main grip around the pole.  For vertical pole applications, I have found overlapping loops to reduce the grip to the pole in the vertical direction (aka, lengthwise direction).  I suspect that's why most established hitches for lengthwise pull do not have overlapping loops at the main grip around the pole.

Hi K4u,

Interesting observation, but a strange one - the inclination of the pole should have no impact whatsoever on the forces present in the knot under load, in fact the KC Hitch works perfectly in any orientation.



The example shown is 3mm polyester braid tied onto a bright chrome pole.  You will notice that under load, the first loop has opened to about 40 degrees and the second has opened to about 10 degrees while the anchor loops have not opened at all.  Load tension causes the first loop to slide along the pole, increasing the angle and so forcing an extension in the cord.  This extension builds significant tension in the cord which increases the grip between the cord and the pole - the greater the load, the more the knot opens and so the feeble friction between the cord and the chrome is increased until the load is met.  If opening the first loop is not sufficient to create ten necessary tension / grip, then the second loop starts to open and on very slippery surfaces, even the third loop may be required to open to generate the required tension / grip.

Sufficient turns should be used so that the last two wraps are not affected when the load is applied - this is the 'root' or 'anchor' of the knot and must be free from any directly applied lateral forces which must all be taken by the expanding loops.  You will see that this is the principle difference between the KC which keeps all 'lengthwise' tension away from the root, while others all take a line to the back of the knot and thereby tend to disrupt the stability of the whole knot.

Derek

Give it a try.

Derek

knot4u

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Re: Best Gripping Hitch for Vertical Pole
« Reply #23 on: July 28, 2010, 04:34:45 PM »
Those hitches in your pics have overlapping loops on the main grip around the pole.  For vertical pole applications, I have found overlapping loops to reduce the grip to the pole in the vertical direction (aka, lengthwise direction).  I suspect that's why most established hitches for lengthwise pull do not have overlapping loops at the main grip around the pole.

I made no comment about the inclination/orientation of the pole in your pics.  By the way, I say "vertical pole" in the original post just so it's clear that we're talking about lengthwise loads.

To clarify, in the knots of your pics, the multiple wraps around the pole overlap each other.  That's unlike almost all other established gripping hitches.  For example, these other gripping hitches have multiple wraps that do not overlap:  Klemheist, Prusik, Gripping Sailor, Isicle, Distel, Mason, Adjustable Grip, Tautline, Camel, Gripping Clove (pic above), Gripping Half (pic above), Gripping Clove (pice above) and some other gripping hitches.

The overlaps take away some friction from the pole (where the friction should be) and apply that friction to the overlapped portion of the rope.  Further, where wraps do NOT overlap in those other gripping hitches I mentioned above, the load applied to the multiple wraps is transferred throughout the multiple wraps, and the friction to the pole therefore increases.  In your knots, because of the overlaps, that extra bit of friction is non-existent.

By the way, I took the time to test your hitches with various ropes and various poles.  So, even if my theory explanation above is inaccurate, the bottom line is that I have found other gripping hitches to perform better for the application in the original post.  I encourage everybody to test all the hitches in this thread.  It's fun.  Also, I came into this thread thinking that a gripping hitch could not get better than the Mason or the Gripping Sailor's.  However, I now have new favorites, and I'm still looking for improvements.  :)
« Last Edit: July 28, 2010, 07:09:37 PM by knot4u »

Dan_Lehman

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Re: Best Gripping Hitch for Vertical Pole
« Reply #24 on: July 28, 2010, 04:53:45 PM »

I cannot follow this. I presume it is not this:


I'm pretty sure it's the hitch in the pic above that I call "Gripping Cow Hitch".  Dressed tightly, the hitch is quite secure.  :)

HALF-BINGO!  -- nice to see words interpreted pretty correctly.
"Gripping Cow" doesn't fit, though:  the gripping part is if anything
*Cloved*, just looking at how the tail proceeds, but in this case I don't
think it will much matter; the *Cow* aspect is only in the finish.

dmaacdd has it right but for his last move, where the tail was brought
around not "away" but near to the knot and makes the forbidden
Half-hitch; knot4u goes wrong on the turn but aces the finish.
And, again, it's sort of 6 of one, half-dozen of other, re that turn, perhaps
-- it's the finish orientation that provides the nicely locking/nipping hold.
And in both cases, the loaded SPart (if pulled as shown) puts added
pressure on the nipped tail.  (And I think one could finish with a sort
of Reversed Ossel Hitch, for like nipping.)


Btw, it seems to me --and was so presented by Gary Storrick's site (which
I think remains NA until he has time to devote to re-constituting it)--
that an extended *Cow*-oriented series of Half-hitches does a
better job at gripping than the like *Clove* series (Storrick named
such a structure "Hitch Series", IIRC (Bob ... ?) ).

I like the way this particularly oriented "cow" structure nips the end
within itself --i.e., independent of pressure/proximity to the
hitched object (!).  The stopper finish is also good, but one could
say is dependent upon there being close proximity to the object.

--dl*
====

DerekSmith

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Re: Best Gripping Hitch for Vertical Pole
« Reply #25 on: July 28, 2010, 07:26:49 PM »
The overlaps take away some friction from the pole (where the friction should be) and apply that friction to the overlapped portion of the rope.  Further, where wraps do NOT overlap in those other gripping hitches I mentioned above, the load applied to the multiple wraps is transferred throughout the multiple wraps, and the friction to the pole therefore increases.  In your knots, because of the overlaps, that extra friction is non-existent.

Hi K4u,

You have made an interesting observation.  One that at first sight is logically true, but on closer inspection turns out to be the opposite.

The frictional grip between the rope and the pole is a function of three aspects - the coefficient of friction between the rope and the pole - the area of contact - the pressure of contact.  In turn, the pressure of contact is a function of the tension in the rope, which as it wraps around the pole translates into a force in towards the centre of the pole, pressing the rope onto the surface and so increasing the frictional grip.

It is true that by taking one line over another, you are removing its contact from the pole, so it cannot have any friction with the pole, but the twist comes from the fact that there is tension in the line and this is manifest as a pressure onto the line below it which significantly increases the pressure of the lower line onto the pole and proportionally increases the rope to pole friction.  In addition to this 'transferred' friction, there is pressure from the top rope upon the bottom rope which (as you pointed out) causes friction between them, and it is highly likely that the coefficient of friction between two ropes is greater than between a rope and a slippery pole surface, so at each crossing point, the ropes are gripping one another quite strongly and 'locking up' the structure quite effectively (try it, load up a KC and then try to move one of the top ropes).

Derek

dmacdd

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Re: Best Gripping Hitch for Vertical Pole
« Reply #26 on: August 02, 2010, 12:58:15 AM »
"Icicle Cow Hitch"



Dress tightly before loading.

Actually, this holds extremely well with a downward load without the bottom cow hitch, as I have found by extensive experience with

which lacks only that bottom cow hitch.

Dan_Lehman

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Re: Best Gripping Hitch for Vertical Pole
« Reply #27 on: August 02, 2010, 05:13:01 AM »
Actually, this holds extremely well with a downward load without the bottom cow hitch,
as I have found by extensive experience with <photo of relatively fine/small cord
on a smooth object> (!!).

Whoa, that simply cannot be:  if you take a strict, little-wiggle parallel
away-from-coil pull, it can hold; but much of any angle to this pull
and that skinny tail will go screaming out of the non-existent nip as the
hitch's collar is pulled away from the object!  Do Not Pass GO !

--dl*
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dmacdd

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Re: Best Gripping Hitch for Vertical Pole
« Reply #28 on: August 02, 2010, 07:13:34 AM »
Actually, this holds extremely well with a downward load without the bottom cow hitch,
as I have found by extensive experience with <photo of relatively fine/small cord
on a smooth object> (!!).

Whoa, that simply cannot be:  if you take a strict, little-wiggle parallel
away-from-coil pull, it can hold; but much of any angle to this pull
and that skinny tail will go screaming out of the non-existent nip as the
hitch's collar is pulled away from the object!  Do Not Pass GO !


You mean like this? (See attached photos.)

It holds very well at angles from 0 to 40 degrees on my marlinespike with 1/16" / 1.6 mm braided nylon cord.  (About 10 lbs force in the photos from my right hand.)

It holds very well at angles from 0 to 40 degrees on a 28 mm wood dowel with 1/8" / 3.2 mm hollow braided nylon cord.
« Last Edit: August 02, 2010, 07:38:32 AM by dmacdd »

dmacdd

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Re: Best Gripping Hitch for Vertical Pole
« Reply #29 on: August 02, 2010, 08:26:05 AM »

You mean like this? (See attached photos.)

It holds very well at angles from 0 to 40 degrees on my marlinespike with 1/16" / 1.6 mm braided nylon cord.  (About 10 lbs force in the photos from my right hand.)

It holds very well at angles from 0 to 40 degrees on a 28 mm wood dowel with 1/8" / 3.2 mm hollow braided nylon cord.

I just tested it with a half hitch continuing around in the same direction as the main body of turns. (This looks like a rolling hitch (ABoK 1734) with extra turns before the finishing half hitch, but the pull is in the opposite direction to that on the rolling hitch. k4u had a picture of this earlier in this thread.).  It holds well to 90 degrees, and just as well at small angles.

So I would have to advocate something other than the hitch shown in the photos in my previous posts here. I'll change my web site. 

I continue to like the well pipe hitch as being the most obvious simple smooth pole hitch -- six or so turns away from the direction of load then a clove hitch around the standing part with the tail.  If you want to make it secure against jerking, you can make a multi turn buntline with six or so turns away from the direction of load then an inverted clove hitch around the SP with the tail.