Easy, no-splice soft shackle!

[rweb82]

I'm curious if anyone has actually experienced a double overhand knot fail on Amsteel (properly cinched down, of course)- or is most of the concern directed toward the possibility that it COULD fail. I'm not trying to be snarky; but I've noticed a recurring theme among many folks here where it seems a mountain is made out of a molehill with regards to certain applications of materials. Everyone is responsible for their own rig...I get it. And personally, I couldn't care less what other folks use/or don't use on their weight-bearing setups. But just because something COULD fail doesn't mean that it ever will, nor that it would even be considered plausible under scientific testing.

Perhaps someone with more knot knowledge than I could elaborate. What is the actual likelihood that a double overhand knot will fail in this application with Amsteel- under reasonable use?

[cmc4free]

Perhaps someone with more knot knowledge than I could elaborate. What is the actual likelihood that a double overhand knot will fail in this application with Amsteel- under reasonable use?

In my unprofessional opinion, probably nigh on zero. A doubled figure 8 would I think be even less likely to slip and fail. And neither is going to weaken the strength of the rope enough that it will break in a hammock application... again, in my unprofessional opinion.



To add in some snark, I thought it was funny that there's a whole video dedicated to making a loop using an overhand knot at the tails of a bight.

[bluesam3]

Oh, this is a thing with a name? It's how my tarp suspension has been attached to the tarp ever since I've had it: makes it much quicker and easier to change which suspension points I'm using (I use a square tarp) than anything else, and with another overhand knot near the non-knot end of the loop, they don't fall off in the bag.

Also, putting a knot in each end makes the larks-head version much easier to untie after it's been loaded.

[Latherdome]

To add in some snark, I thought it was funny that there's a whole video dedicated to making a loop using an overhand knot at the tails of a bight.

I admire just how simple it can be: highlights the strengths of the material and of the brain versus advanced splicing and tying skills.



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[jeff-oh]

I'm curious if anyone has actually experienced a double overhand knot fail on Amsteel (properly cinched down, of course)- or is most of the concern directed toward the possibility that it COULD fail. I'm not trying to be snarky; but I've noticed a recurring theme among many folks here where it seems a mountain is made out of a molehill with regards to certain applications of materials. Everyone is responsible for their own rig...I get it. And personally, I couldn't care less what other folks use/or don't use on their weight-bearing setups. But just because something COULD fail doesn't mean that it ever will, nor that it would even be considered plausible under scientific testing.

Perhaps someone with more knot knowledge than I could elaborate. What is the actual likelihood that a double overhand knot will fail in this application with Amsteel- under reasonable use?

This is not snarky but a fair question, however it is two questions in one. The 1st simple answer is yes, Testing has been done and has shown that for a tied knot with the tails coming out the end like shown, the knot can roll and invert causing the soft shackle to fail. (I do not remember the specific knot tested at this time. In testing this happened prior to fiber failure (i.e. line breaking). Load testing also showed that the button knot with the tails spliced back into the line was shown to prevent this failure mode. So yes with enough load you can fail the line.

Now for the second part of your question... Do we care, or need to worry? That comes down to the Margin of Safety. Defined as Capability/Applied Load-1. On the very low side I have seen test results that showed soft shackle failure as low as 50% of capability. Thus for a normal 2 line soft shackle the capability would be expected to be 1400lbs. (1400lbs * 2 lines * 50% knot Knockdown). Assuming a 175 lb person, 30 deg hang angle, the Margin of Safety would be 1400 lb capability/175lb load -1 = 8-1 or a MS = 7. Go hang and have a beer. Under the load your applying it would not be expected to fail.

Great point. The load required to make the soft shackle fail is much higher than the loads we typically apply. Now, if the know slips out of the loop/bite... That's a different concern as this is most likely at no to little load and show itself when you get in the hammock.

Thank you

[bluesam3]

This is not snarky but a fair question, however it is two questions in one. The 1st simple answer is yes, Testing has been done and has shown that for a tied knot with the tails coming out the end like shown, the knot can roll and invert causing the soft shackle to fail. (I do not remember the specific knot tested at this time. In testing this happened prior to fiber failure (i.e. line breaking). Load testing also showed that the button knot with the tails spliced back into the line was shown to prevent this failure mode. So yes with enough load you can fail the line.

Now for the second part of your question... Do we care, or need to worry? That comes down to the Margin of Safety. Defined as Capability/Applied Load-1. On the very low side I have seen test results that showed soft shackle failure as low as 50% of capability. Thus for a normal 2 line soft shackle the capability would be expected to be 1400lbs. (1400lbs * 2 lines * 50% knot Knockdown). Assuming a 175 lb person, 30 deg hang angle, the Margin of Safety would be 1400 lb capability/175lb load -1 = 8-1 or a MS = 7. Go hang and have a beer. Under the load your applying it would not be expected to fail.

Great point. The load required to make the soft shackle fail is much higher than the loads we typically apply. Now, if the know slips out of the loop/bite... That's a different concern as this is most likely at no to little load and show itself when you get in the hammock.

Thank you

Adding another overhand knot to make the loop that you're passing the knot through smaller could mitigate that last problem nicely.

[cmc4free]

I admire just how simple it can be: highlights the strengths of the material and of the brain versus advanced splicing and tying skills.



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I'll concede that the second half of the video was more interesting - showing various methods of giving the simple loop the functionality of a more conventional soft shackle. Not all of those would have been obvious to a novice.

[rweb82]

Assuming a 175 lb person, 30 deg hang angle, the Margin of Safety would be 1400 lb capability/175lb load -1 = 8-1 or a MS = 7. Go hang and have a beer. Under the load your applying it would not be expected to fail.

Thank you for providing a more detailed analysis. This is more of what I was getting at. Not necessarily wondering if Amsteel has been tested to absolute failure using hydraulic equipment/winches, etc... I know that has been done before, and that at some point, any knot will fail. But given our usage of these materials, would any of us hammock hangers ever come close to putting this crude soft shackle under enough stress to cause absolute failure (not factoring in user error)? I am inclined to think the answer is no.

[gunner65]

I have access to an Instron Electro-mechanical test rack. If anyone would like to put any of these systems to a static pull test I can arrange that. Just PM me.
instron.png

[Arthurpan12]

I like splicing and knot tying... I find it rather... Meditative?

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