Double fisherman's hitch testing

Re: Double fisherman\'s hitch testing

That is really great link thanx! Another example of the elasticity/ stretch releif saving a system, more than static strength i think.

My imagery model of this has always been that it has dynamic absorbtion capability to make it so strong. Even on a static pull!

The strength of most hitches i think would depend on the size of their mount ro the primary arc of the line, outside of which the knot fails (from back pressure from the stiffness of the arc, felt out in front of the arc?). But, with this fisherman's barrel; see higher numbers.

i think tension relieving slip is built in 2 ways(both through the coils), to give this compensation; giving higher test scores than other choices similarily mounted; invoking same bend. As we go to 3 turns/coils these numbers increase favorably. i think the coils are a stash of elastic line to draw from; and also, the coils grip back to the standing part, so the slide releif, has to work through there too. But, it can be done; and the releif given. The key i think is that the system chokes itself, and is barely capable to meter out the releif, but it happens; in varying loading ranges. The more weight, the harder the system makes it to get the reielf; becuase of the chokes on the standing part. Heat sink given by the carabiner. This is all part of the reason i think Round Turn bases are the superior working knots; implemented in bowlines for DBY, 2 Round turn strategies, for friction hitch etc.

The 3 coil version; some quote to 100% efficiency; but if there is to be another arc in the line; that high efficiency to chase would be unmatched and superfluous.

i think a round turn overhand/ double overhand knot is an anchor, and this fisherman's barrel etc. to be an anchor hitch to self to form eye. An Anchor to me is the simplest form of the bus pull trapping what a baby could hold to secure. The turns reducing the tension in the line, so that one end is baby pull and one end is bus pull etc. Knots based on a simple turn, niot getting the full affect of the self checking choke, nor frictional differance, as well as this elasticity resevoir. Much better strategy base module. A Blake's carries this too, and self traps well enough to not walk, in this Anchor Hitch fashion; though i'd always back it up; but it is tanding on it's own bottstrap 2x, after 4 turns to reduce force that it takes to hold bootsrap!.
 
Re: Double fisherman\'s hitch testing

Nice article, Tom. Do you know what is meant by the knot's having "low gain"?

Also, even though this article basically answers a question I have, I'll ask you and the buzzheads anyway: we know the greater the bend radius of a rope, the less strength loss there is in a rope tied to something, like a rope snap or biner...using thimbles gives greater bend radius but do you guys use them with your lanyards and climbing lines, or maybe no because even with no thimble there is so huge a safety factor in the rope strength that a thimble is not necesary?
 
Re: Double fisherman\'s hitch testing

[ QUOTE ]
Do you know what is meant by the knot's having "low gain"?

[/ QUOTE ]

"Low gain" means that the length the knot adds to a system is minimal. This is particularly important in ascending and rescue raising systems in which a "shorter" knot will get you closer to the top anchor or redirection point.

For instance, you can use a figure-8 on a bight for a carabiner tie-in, but however small you try to tie the loop knot, it will have a lot more "gain" than a simple noose knot like the double overhand noose (which is the correct name for the knot under discussion).

- Robert
 
Re: Double fisherman\'s hitch testing

[ QUOTE ]
using thimbles gives greater bend radius but do you guys use them with your lanyards and climbing lines, or maybe no because even with no thimble there is so huge a safety factor in the rope strength that a thimble is not necesary?

[/ QUOTE ]

My thought is that the system is weakened more by the cross loading biners that would happen with a thimble, than with the strength loss due to bend radius.

Dave
 
Re: Double fisherman\'s hitch testing

yeah, for the cavers cows tails one of the bonuses of this knot is that it forms a nice chunky handle and the biner stays in place. I've seen people use fig 8s and the clip just flops around all the time...no chance of crossloading with this fishermans knot....

we call it a barrel knot in Australia. The whole fishermans business confuses me.

It makes a passable monkeys fists, you can add several several wraps and make a nice big noose knot, which should pull through if it gets stuck...does anybody else use it for moving between branches?
 
Re: Double fisherman\'s hitch testing

[ QUOTE ]
we call it a barrel knot in Australia. The whole fishermans business confuses me.

[/ QUOTE ]
As it should--"dbl.fisherman's" is a misnomer, and should be killed.
A Dbl.Fisherman's knot is an extension of the (naturally) (single) Fisherman's,
which is a pull-together bend of two Overhand knots; the Dbl. uses Dble Oh.s.
So there's no "fisherman's" here. (Heck, this is in Ashley, but I'm not w/copy handy.)

It should be called a Strangle Noose (the *hitch* being thus just the knot on
the object directly, not around the SPart).
Not a clear nomenclature, but less muddy than the clear misuse of "Fish.". (-:

Nice to see some testing.

Btw, I often see folks talking about trashing dubious ropes;
it would be better were such material fed into a test lab
(sometimes just to see whether the suspected defect was in fact
that--to improve evaluation methods).

Thanks,
(-;
 
Re: Double fisherman\'s hitch testing

My thought is that the system is weakened more by the cross loading biners that would happen with a thimble, than with the strength loss due to bend radius.

But what about with rope snaps where there is no cross loading?
 
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