knots and anchors

Hi all,
Seizings can make a 100% efficient termination, but not in every rope, with every twine. For instance, I tried seizing uncovered Spectra, and the ends pulled through at, as I recall, about 40% of break. Tried it with many turns, with nylon twine, with Spectra twine, tried it with massive leverage on the seizing stick, with obsessively tightened frapping turns, with service under the seizing. Pulled right out.
Simple nylon twine seizings, "stacked" on Dacron or Nylon rope, are another matter. Same with wire rope. So while I'm a big fan of seizings, they have their limitations, and they are quite skill-intensive.
How else, then, to get acceptable strength? For field work, only splices are potentially 100% efficient (again, given skill), so if you don't splice, you have to increase rope size/strength, or live with a lower safety factor. Any rope that you elect to knot must be sized to take into account the loss of efficiency caused by that knot.
In the present case, that hot pink seizing appears to be keeping any load that gets to the end from setting the knot. Traditionally, this tack was used to make knots in large rope easier to untie, notably in the Carrick Bend. But even there I don't think it added anything to knot efficiency.
Fair leads,
Brion Toss
 
[ QUOTE ]
I tried seizing uncovered Spectra, and the ends pulled through at, as I recall, about 40% of break. Tried it with many turns, with nylon twine, with Spectra twine, tried it with massive leverage on the seizing stick, with obsessively tightened frapping turns, with service under the seizing. Pulled right out.

[/ QUOTE ]
Sounds like a need for *palm-&-needle* seizings! ;)
[ = stitching ]

Of course, 40% of HMPE break is WAY up there, to what one
thinks of for line of a size (i.e., about tensile limit of
the trad. fibers).

[ QUOTE ]
In the present case, that hot pink seizing appears to be keeping any load that gets to the end from setting the knot.

[/ QUOTE ]
Pretty much; or it greatly ameliorates the delivered
setting force, which would now come in halved amount from
both ends.

[ QUOTE ]
Traditionally, this tack was used to make knots in large rope easier to untie, notably in the Carrick Bend. But even there I don't think it added anything to knot efficiency.

[/ QUOTE ]

I've never seen strength data for the open carrick bend
(i.e., in lattice form and seized). And I can't see how it
could be other than the strength of the seizings --for what
happens between them is coming at 50% of the load per strand
(the seizing point having split the load).

As for the hot pink, oh, I like it! And the other choices
--as noted, it can be handy color coding for some purpose.

*kN*
 
[ QUOTE ]
[ QUOTE ]
I tried seizing uncovered Spectra, and the ends pulled through at, as I recall, about 40% of break. Tried it with many turns, with nylon twine, with Spectra twine, tried it with massive leverage on the seizing stick, with obsessively tightened frapping turns, with service under the seizing. Pulled right out.

[/ QUOTE ]
Sounds like a need for *palm-&-needle* seizings! ;)
[ = stitching ]

Stitching gives no help in this case. In a splice, the stitching ordinarily is there just to hold things until the "handcuff effect" of splice compression kicks in. The only compression here is the seizing, and the rope narrows and crawls out from under it.

Of course, 40% of HMPE break is WAY up there, to what one
thinks of for line of a size (i.e., about tensile limit of
the trad. fibers).

True, but I want to scale things, whenever possible, to ultimate strength. Another way to think of this is getting the same safety factor with less money. Also weight and windage in sailboats, at least.

[ QUOTE ]
In the present case, that hot pink seizing appears to be keeping any load that gets to the end from setting the knot.

[/ QUOTE ]
Pretty much; or it greatly ameliorates the delivered
setting force, which would now come in halved amount from
both ends.

[ QUOTE ]
Traditionally, this tack was used to make knots in large rope easier to untie, notably in the Carrick Bend. But even there I don't think it added anything to knot efficiency.

[/ QUOTE ]

I've never seen strength data for the open carrick bend
(i.e., in lattice form and seized). And I can't see how it
could be other than the strength of the seizings --for what
happens between them is coming at 50% of the load per strand
(the seizing point having split the load).

True, but then you wouldn't be much lower in efficiency than a drawn-up bend would provide, and you could still untie the darned thing.

As for the hot pink, oh, I like it! And the other choices
--as noted, it can be handy color coding for some purpose.

*kN*

[/ QUOTE ]
 
[re-casting Brion's reply here, to make quotes conspicuous]

- - - - - -

[ QUOTE ]
[ QUOTE ]
I tried seizing uncovered Spectra, and the ends pulled through at, as I recall, about 40% of break. Tried it with many turns, with nylon twine, with Spectra twine, tried it with massive leverage on the seizing stick, with obsessively tightened frapping turns, with service under the seizing. Pulled right out.

[/ QUOTE ]
Sounds like a need for *palm-&-needle* seizings! ;)
[ = stitching ]

[/ QUOTE ]
Stitching gives no help in this case. In a splice, the stitching ordinarily is there just to hold things until the "handcuff effect" of splice compression kicks in. The only compression here is the seizing, and the rope narrows and crawls out from under it.

[ QUOTE ]
Of course, 40% of HMPE break is WAY up there, to what one
thinks of for line of a size (i.e., about tensile limit of
the trad. fibers).

[/ QUOTE ]
True, but I want to scale things, whenever possible, to ultimate strength. Another way to think of this is getting the same safety factor with less money. Also weight and windage in sailboats, at least.

[ QUOTE ]
[ QUOTE ]
Traditionally, this tack was used to make knots in large rope easier to untie, notably in the Carrick Bend. But even there I don't think it added anything to knot efficiency.

[/ QUOTE ]
I've never seen strength data for the open carrick bend
(i.e., in lattice form and seized). And I can't see how it
could be other than the strength of the seizings --for what
happens between them is coming at 50% of the load per strand
(the seizing point having split the load).

[/ QUOTE ]

True, but then you wouldn't be much lower in efficiency than a drawn-up bend would provide, and you could still untie the darned thing.

[ - Brion - ]
 
[ QUOTE ]
Something that Pete Donzelli taught me was that knots and hitches don't make ropes weaker. They make them less efficient. -Tom Dunlap

[/ QUOTE ]

Short answer:
The rope as a device, can only resist/conduct on the inline axis; and only in the tension direction (on that inline axis).

forcesPulley_1.swf




Theory:
Any deformity /deflection from pure inline, can reduce line efficiency by : Deforming around mount to use less fibers for same load support(less efficient), or by bending to reduce the amount of total line tension that is exerted/necessary on target / inline (less efficient, and raising line tension more toward capacity but not exerting all on load) in trade for bent lines pulling towards each other with the unused part of lineTension not supporting loading.

This same math would be true in rigging dimensions and smaller dimensions inside a lacing ('knot') as well. Lifting with hooks, slings, chokers etc. when trying to stay narrow angle to 'Sweating/Swigging' , bending tightened anchor lines etc. on the wide angle.



Overflow:
If instead of just bending standing you take additional turns around it, can 'stabilize' forces some by spreading out deformity over longer distance/ less impacting. (Best to have single turn on anchor). So fisherPerson's, many mono filament, adjustable hitch etc. use this strategy.


A tension less anchor to me is 1 that the Standing Part is only deformed by the mount not by any other line contact leveraging(but still not best name). To me an important point to examine to understand all forces involved, by understanding position before the Standing Line deformed / leveraged again (Timber, choker, splice etc.; even if not favored by some in actual use(?).
 
I teach mine different knots are stronger than others and each knot has its place. But my main rule is know the limits of each and play with in it if you bite off more than you can chew you'll choke and be in trouble. That's how I try to keep it basic.
 
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