Author Topic: Half turn hitches  (Read 13794 times)

[Inkanyezi] gone

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Re: Half turn hitches
« Reply #15 on: July 30, 2009, 09:09:21 AM »
I have tried the inside clinch hitch for some time, and it works well. I also successfully used just one half hitch and nothing more, under the same condition, that only one pass through the hole is possible. The single half hitch works fine, but when it is not under load, a condition that not is usual for a halyard, it may untie itself if the line is stiff and springs back so that it does not keep the nip. Under load however, in polyester double braid, it is secure enough for a halyard.

Unlike the inside clinch, which nips hard and keeps the nip, the single half hitch is easily untied.
« Last Edit: July 30, 2009, 09:52:25 AM by Inkanyezi »
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Dan_Lehman

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Re: Half turn hitches
« Reply #16 on: July 30, 2009, 06:55:08 PM »
>> works fine, but when it is not under load, a condition that not is usual for a halyard,

It would seem that a simple stopper knot here -- Overhand or Ashley's or Fig.8 --
would also work well, and I wonder at its strength.  But, when slack, there'd be
nothing keeping the knot up against the small-eyed shackle.

--dl*
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Dan_Lehman

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Re: Half turn hitches
« Reply #17 on: August 02, 2009, 04:25:45 AM »
I couldn't resist trying some more variations, considering the problem of only one pass through the eye of the snapshackle. The buntline hitch is of course good enough, as well as a knot with a constrictor around the standing part, but I was looking for something simpler. Considering a simple half hitch would not be secure enough, I added a round turn under the half hitch, effectively making the Inside Clinch #1845, but without seizings. It is secure when tied in this way. The only negative thing to say about it is that it is quite a bit more difficult to untie than the anchor bend.

I have not yet tried it in slick material, but in ordinary polyester rope, it is quite convincing. Jerks will not make it slip.

I have to wonder if it might slip in non-slippery rope (maybe slippery too) under high
load?  -- the mechanism being this:  the sort of friction grip that the turns give leads
to the upper (for a line pulling up) end of the coil to be drawn away from the shackle
eye sufficient to put space below and enable the end to rotate out?!  Although the structure
is --in my thinking, structurally-- a noose-hitch , this doesn't mean that the knotted
part (here, just a coil between end, S.Part , & shackle) will slide down to abut the object.

[edit:  No more "wondering":  this Inside Clinch doesn't even begin to hold
in the square-ish diamon braided poly-combo (PP Z, PES S lay) 5/16" rope around a
'biner -- slips in mere manual force (until the bit of rigidity got from the tight, Extended
Strangle whipping at the end comes to the knot (and I give up putting more load)).
NB:  my circumstance has a larger-dia. ring relative to rope dia. than Inkanyezi's.]

Another idea:  tie a stopper knot; and to keep the knot in place absent tension,
make a wrap with the end of the S.Part and tuck it back into the stopper; this
wrap should see no big increase in load, which will end in the stopper.  !?
(I found this sort of construct where an Overhand stopper was used
in a commercial fishing steel clip, its end then hog-ring-stapled to the S.Part.)
[AHA!  new-knot claim #20090801a23:21 !  (I'll sign myself a CON tomorrow.)]

--dl*
====
« Last Edit: August 02, 2009, 04:44:42 AM by Dan_Lehman »

Sweeney

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Re: Half turn hitches
« Reply #18 on: August 02, 2009, 08:57:48 AM »
Quote
Another idea:  tie a stopper knot; and to keep the knot in place absent tension,
make a wrap with the end of the S.Part and tuck it back into the stopper; this
wrap should see no big increase in load, which will end in the stopper.

I may be missing the point here but why not put an overhand stopper either side of the shackle eye?

Barry

[Inkanyezi] gone

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Re: Half turn hitches
« Reply #19 on: August 02, 2009, 09:43:39 AM »
Of course the size and shape of the eye is important for the knot to nip. I wouldn't consider it for anything else than this type of snapshackle, typical for halyards. Halyards also have a fairly constant tension that shouldn't be harder than to stretch the sail correctly, and they are not exposed to shock loads. Under typical tension for a halyard, the knot holds with a typical double braid line that fills the eye. It seems as an important factor for the nip is that the material thickness of the eye allows the rope to nip the bottommost turn. I tried tying it to different size marlingspikes and found it to nip only when the object diameter, its material thickness, is considerably less than the diameter of the rope. And to set the knot properly, it must be worked down against the object while applying tension.

In the picture it can be seen that the marlingspike is pressed into the last turn somewhat, and that the turn is also held tight by the part that goes back to the top of the knot. If the object is thicker, this part is held more open and allows the end to slip. This spike is about the same thickness as one of the strands.
« Last Edit: August 02, 2009, 10:53:27 AM by Inkanyezi »
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[Inkanyezi] gone

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Re: Half turn hitches
« Reply #20 on: August 02, 2009, 12:34:49 PM »
Considering the possibility of using any knot for something where it is unsuitable (inside clinch and biner), I have had a closer look at what people tie to their harness. In climbing, the bowline is not recommended, unless secured with a strangle knot to the leg of the bight. The more common knot is a rethreaded figure eight loop, tied directly to the harness. I have also seen the zeppelin loop used, and it seems amply secure, although I do not know about any testing. The knot I was thinking of as a replacement is the Wave loop, presented by Waveling. The knot form is identical to the Carrick Bend, and it might be just as good as any of the other three, but before recommending it I would want to try it for double length drop with a sandbag. The obvious difference compared to the other knots is that it might not jam as the fig 8, thus will be easier to untie after a serious fall, probably even easier than the zeppelin. The wave loop is about as easily tied as a bowline. 
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Dan_Lehman

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Re: Half turn hitches
« Reply #21 on: August 05, 2009, 12:12:03 AM »
I may be missing the point here but why not put an overhand stopper either side of the shackle eye?
Barry
Because you don't want to compromise the strength of the line so much,
and you might want to UNtied the knot sometime.

--dl*
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[Inkanyezi] gone

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Re: Half turn hitches
« Reply #22 on: August 05, 2009, 08:40:50 AM »
I may be missing the point here but why not put an overhand stopper either side of the shackle eye?
Barry
Because you don't want to compromise the strength of the line so much,
and you might want to UNtied the knot sometime.

--dl*
====

Also, for a halyard, you might want it to get as high as possible, and if you tie a stopper either side, there will be at least some distance between them. Then the snapshackle would not come up as tight to the shiv as if you have something that stops directly on top of the snapshackle. It would perhaps not be much more than about two inches for the knot and the distance between them, but it might be unwanted. There's hardly any risk of approaching breaking load on a halyard. Too hard tension would compromise the shape of the sail. Regarding untying, the inside clinch, well set, is about as hard to untie as a stopper. A single half hitch is easier to untie, but for a cautious sailor might seem minimalistic.
« Last Edit: August 05, 2009, 11:24:39 PM by Inkanyezi »
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