Why even bother with the hook? (1 Viewer)

[Mace]

These soft shackles are made out of winchline, and are loops. So division of load is identical.

A loop in the winch-line is a loop in the winch-line no matter what terminology you use to describe it.

When you set up a line with 2 legs, each leg carries half the total load. Example, a 3/8 line rated at minimum of 17,600 set up using a block can be loaded up to 34,000 if you take into account your attachment points and the load they can carry. The shackle works on the same principle but you have to factor in the derate of whatever stopper knot is being used.

An eye in a line terminates back into a single line. Which is why normally when a line breaks, it breaks somewhere in the working part of the line, not the eye. The eye falls under the same principle of having 2 legs to halve the load.

I think you are seeing what I am trying to say.

Ignoring the rest of the winch-line and focusing on the loop at the end.
What fundamentally makes a loop in the winch-line "require" a thimble and a soft shackle does not? Obviously there are knots and slightly different weave designs involved and that changes things slightly but the simple fact is that you are taking a piece of winch rope and making a loop out of it. Then you are attaching a shackle (or a hook) directly to that piece of winch-line.

 

[Southeast Overland]

How does this relate to the soft shackles then?
https://forum.ih8mud.com/vendor-marketplace/596333-southeast-overland-soft-shackles.html

What fundamentally makes a loop in the winch-line "require" a thimble and a soft shackle does not? Obviously there are knots and slightly different weave designs involved and that changes things slightly but the simple fact is that you are taking a piece of winch rope and making a loop out of it. Then you are attaching a shackle (or a hook) directly to that piece of winch-line.

This thread took off! Thanks for the questions Mace.

Soft shackles are made out of synthetic winch line. The Southeast Overland soft shackles are made out of 3/8" and 1/2" Amsteel Blue, Dyneema SK75 fiber line.

It would be great to have a thimble on either end of a soft shackle but the construction and use of the soft shackles does not allow this as soft shackles are designed to be able to be opened and fastened around objects that a hard shackle cannot attach to easily.

Soft shackles should have a minimum bend radius maintained to maximize their strength with the minimum bend radius calculated off the soft shackles overall width. I know this will not happen as most soft shackles get attached to a 3/4" hard shackle with a 7/8" pin or something similar - so that is how I have my soft shackles load tested - on smaller bend radius shackles then what would maintain their top strength.

I want my products tested in "real world" conditions. What I find is approximately 3 out of 4 soft shackles break at the base of the knot which is an inherent weak point due to the bend that gets accentuated at the base of the knot when the soft shackles are heavily loaded. The remaining 1 out of 4 soft shackles break where they bend around a shackle pin. I would bet if you kept the soft shackles attached to a sufficiently large enough (radius) point then almost all would break at the base of the knot.

It is still important though to not put a soft shackle, synthetic winch line, steel winch line, strap, or any similar recovery gear piece of equipment over an edge - whether or not that edge is sharp or just a 90 degree bend - all such recovery gear listed above will have their strength degraded by sharp bends whether they be smooth and curved or angular and abrupt.

As opie said synthetic winch line and soft shackles should not be shock or dynamically loaded. The base material does have a memory and its strength can be degraded by shock loading which will/can present itself in the future with a broken line. I stress this in the classes I teach. It is important.

Little topic change back to the original topic...

It is fine to not run a thimble but you do need to run some significant abrasion guard and pay attention to the attachment point. Thimbles help in several ways, significantly they help newbies rig line more so in a correct fashion and also help more experienced wheelers from making a mistake when they get in a hurry.

Mace - PM me your shipping address. I'll send you a soft shackle to play with. Feel free also to call the store @ 864-280-4238. I'm happy to talk with you at length about soft shackles or any other products. I could type all day and still not get everything said.

 

[Mace]

Thanks for the reply Eventhough.
I really wanted to ask you about this exact thing in your for sale thread but did not want to be seen as a dig on your product in there. I am certianly not bashing it at all, I think it's a great idea and use for winchline drops.

Good point on the rigging of winchlines and thimbles. Winching is so often a nonstandard (and sometimes dangerous) situation that having a little extra nudge in doing things properly is a great idea.


The winch I just bought has a thimble on the synthetic line, but it is one of the easily crushable stainless open ones and honestly, I feel more comfortable without a thimble than with the easily deformed thimble that is on the winchline currently. It just really looks like it could deform and cut into the synthetic line.

 

[Southeast Overland]

Thanks for the reply Eventhough.
I really wanted to ask you about this exact thing in your for sale thread but did not want to be seen as a dig on your product in there. I am certianly not bashing it at all, I think it's a great idea and use for winchline drops.

Good point on the rigging of winchlines and thimbles. Winching is so often a nonstandard (and sometimes dangerous) situation that having a little extra nudge in doing things properly is a great idea.


The winch I just bought has a thimble on the synthetic line, but it is one of the easily crushable stainless open ones and honestly, I feel more comfortable without a thimble than with the easily deformed thimble that is on the winchline currently. It just really looks like it could deform and cut into the synthetic line.

Post up any questions you want - I welcome questions! It is just sometimes hard to explain everything in type without going on forever and ever and ever...

I have a pic I need to post of a D-E-S-T-R-O-Y-E-D open thimble that I just replaced on a customer's budget winch line. It only had two light pulls on it and was ruined.

You are correct also - I'd prefer to have a soft eye than a cheap and likely to not do jack to protect your eye weak open thimble.



PM returned - shoot me an email address too for tracking info.

 

[opie74]

I think you are seeing what I am trying to say.

Ignoring the rest of the winch-line and focusing on the loop at the end.
What fundamentally makes a loop in the winch-line "require" a thimble and a soft shackle does not? Obviously there are knots and slightly different weave designs involved and that changes things slightly but the simple fact is that you are taking a piece of winch rope and making a loop out of it. Then you are attaching a shackle (or a hook) directly to that piece of winch-line.

OK, I see what you are asking now.

An eye in synthetic line does not "require" a thimble as a blanket parameter. I believe someone mentioned what a thimble provides any material one is put in.. It holds a minimum bend radius of the material it is installed in, and it protects the material from abrasion. There are many scenarios where both of these issues can be addressed based on use and protection minus a thimble.

How a soft shackle gets away with absorbing the derate of a sharp bend is it is X times stronger than a single line of the same diameter material. So say you have a 3/8 soft shackle attached to a 3/8 synthetic winch line. The minimum rating of the winch line is 17,600 and we will use Southeast Overlands rating of 29,000 for a 3/8 soft shackle. His 3/8 shackle is 1.65 times stronger than the line its attached to. So it can absorb a 60 percent derate and still be as strong as the line its attached to. Hence, no need for a thimble since it would take a very sharp bend to derate the shackle to the minimum strength of the line. And just using the diameter of the 3/8 line itself as a setpoint, the shackle around that will not derate it 60%.

There are thimbles you can purchase that can be moved around on a line, taken off etc if you want to go that route. If you click the link below you will see a cast thimble right in the center at the top of the first page. These can be had in varying sizes....

http://www.samsonrope.com/site_files/Special_Tips_for_splicing_Double_Braid_Ropes.pdf

You can also see variations here... Scroll down to items 920 and 929

http://www.samsonrope.com/site_files/Chafe_Gear_Brochure_June_2011.pdf

 

[Southeast Overland]

How a soft shackle gets away with absorbing the derate of a sharp bend is it is X times stronger than a single line of the same diameter material. So say you have a 3/8 soft shackle attached to a 3/8 synthetic winch line. The minimum rating of the winch line is 17,600 and we will use Southeast Overlands rating of 29,000 for a 3/8 soft shackle. His 3/8 shackle is 1.65 times stronger than the line its attached to. So it can absorb a 60 percent derate and still be as strong as the line its attached to.

The Southeast Overland 3/8" soft shackles have a 29,000 average break strength, and a 7,250 WLL at a 4:1 safety factor. See that info HERE. The 29,000 lb average break strength is when attached to a minimum 7/8" pin (from a 3/4" shackle). If you wrap that 3/8" soft shackle around a smaller radius bend like on a tube thimble the strength of the soft shackle will be degraded to a degree since the tube thimble will impart a sharper bend than what the 3/8" soft shackle was load tested on.

Winch lines straight 'out of the box' have a woefully low safety factor. 3/8" Amsteel Blue has a average break strength of 19,600 lbs. If you apply a 4:1 safety factor like on the soft shackles then you have a WLL of only 4,900 lbs. If used on a 8,000 lb winch and you consider the 8,000 lbs a WLL then the safety factor is only 2.45 for new line in perfect condition. If you were using 5/16" Amsteel Blue then your average break strength would be decreased on a new, perfect line to 13,700 lbs and on a 8,000 lb winch if the 8,000 lbs was considered a WLL then you would only have a 1.7:1 safety factor.

The method of setting a 8,000 WLL for a 8,000 lb winch is not even adequate or proper since a 8,000 lb winch can often pull more than that 8,000 lb rating, and a dynamic shock to the line can easily double that number again. Wear and tear will decrease the line's break strength also. One has to seriously consider the impact of dynamic shock loads incurred when winching, and their impact later since a synthetic winch line can 'remember' that shock load, not break at that time, but be weakened and break later.

With all that being said - lets be sure we are comparing apples to apples when talking break strength (average, minimum), WLL versus break strength, and safety factors (4:1, 2.45:1). The Southeast Overland soft shackles have a WLL set since they are a shackle and used similar to a hard, metal shackle, even though there is less mass to recoil if one breaks and therefore they are less dangerous due to their smaller mass if breakage does occurs. A WLL on a soft shackle of 7,250 lbs is also hard to compare to a winch line that has a stated average break strength of 19,600 lbs. Many will consider the winch line to be stronger than the soft shackle but this is not true if you compare apples to apples.

In addition to knowing, understanding, and portraying break strengths and WLLs equally, we also need to understand how these products are actually used when wheeling and performing recoveries, both in 'perfect' conditions and the most horrible muddy, cold, wet, and rocky conditions that sometimes are more frequent than the perfect conditions we wished we always encountered. I use synthetic line a lot when wheeling - both on winch lines and with soft shackles. My choice winch line is 3/8" Amsteel Blue, orange color (for safety). I use the 3/8" soft shackle a good bit along with a 1/2". Both have performed well. The 1/2" provides extra strength when dynamic loads and stronger winches come into play. I wheel a lot and end up winching a lot - both myself and others. My recovery gear tells the tale of use and really allows these products to be field tested well.



Oh, Mace - your merchandise is packed up and ready to go!

 

[opie74]

Steve, I was just attempting to illustrate the shackles ability to sustain significant derate and still be stronger than the line it is theoretically attached to. Mace was asking why the idea behind a thimble in a winch line to maintain a set radius in the eye did not apply to a shackle. I was trying to show its because the shackle is X times stronger than the line and even with some derate, its still stronger than the line.

Since the manufacturer lists tensile strengths, it makes sense to compare the tensile strength of the shackle to it. However, even if you place an even 4:1 on both the shackle and the line, the shackle is still stronger.

 

[Mace]

Steve, I was just attempting to illustrate the shackles ability to sustain significant derate and still be stronger than the line it is theoretically attached to. Mace was asking why the idea behind a thimble in a winch line to maintain a set radius in the eye did not apply to a shackle. I was trying to show its because the shackle is X times stronger than the line and even with some derate, its still stronger than the line.

Since the manufacturer lists tensile strengths, it makes sense to compare the tensile strength of the shackle to it. However, even if you place an even 4:1 on both the shackle and the line, the shackle is still stronger.

No offense amigo but you never really got what I was asking.
I was not talking about the winchline itself, I was talking specifically about the eye at the end of the winchline and why thimbles are a good idea on the Eye of the line but not in the soft shackles.

In the end it is not because it would not help, but because the soft shackles design pretty much precludes the ability to mount a thimble (would not be a very soft shackle then). And in real world tesing, they appear to break at the base of the knot anyway.

 

[Southeast Overland]

Steve, I was just attempting to illustrate the shackles ability to sustain significant derate and still be stronger than the line it is theoretically attached to. Mace was asking why the idea behind a thimble in a winch line to maintain a set radius in the eye did not apply to a shackle. I was trying to show its because the shackle is X times stronger than the line and even with some derate, its still stronger than the line.

Since the manufacturer lists tensile strengths, it makes sense to compare the tensile strength of the shackle to it. However, even if you place an even 4:1 on both the shackle and the line, the shackle is still stronger.

I wasn't jumping on you.

 

[60Works]

When you set up a line with 2 legs, each leg carries half the total load. Example, a 3/8 line rated at minimum of 17,600 set up using a block can be loaded up to 34,000 if you take into account your attachment points and the load they can carry. The shackle works on the same principle but you have to factor in the derate of whatever stopper knot is being used. Thats why they are not twice as strong as a single line of the same diameter material being used. Each type of stopper knot is different in what it does to the line inside the knot.



2 legs instead of one.



You'll be fine without a thimble as long as you pay attention to bend radius and abrasion. Most of the shackles used in the offroad industry use pins of a sufficient radius that a thimble is not necessary. Where you would have an issue would be a rope on rope situation.



An eye in a line terminates back into a single line. Which is why normally when a line breaks, it breaks somewhere in the working part of the line, not the eye. The eye falls under the same principle of having 2 legs to halve the load.

I think Mace is right on the physics involved with the soft shackle. It is not a 2 leg application. Just like the winch line, the eye of the soft shackle terminates back into itself. It is the same single strength line. One cut of either the loop or the eye loop will completely disconnect the pull. A 2 leg application would require 2 cuts. The soft shackle is very usefull to make a connection but it is not any stronger than a winch line of the same material.

 

[60Works]

"When you set up a line with 2 legs, each leg carries half the total load. Example, a 3/8 line rated at minimum of 17,600 set up using a block can be loaded up to 34,000 if you take into account your attachment points and the load they can carry."

OK. I'm finally tracking your example of a shackle eye working like a single pulley snatch block, Opie. You are correct but there are some practical limitations. It is a trade off between the cutting action of the pin and the increased loading caused by the angle of the thimble.

A thimble protects the line from cutting forces and abrasion but increases leg load because of the increased angle the legs have to spread to accomodate the thimble. It is possible to have the sum of the leg loads be higher than the original load. Each leg has the load divided by the cosine of the angle of the leg. Small angles (less than 15°) are neglible but at (an unlikely) 60° leg load is doubled.

edit - stuffing a really large diameter steel shackle pin through an winch line's unthimbled eye could cause really sharp angles on the legs of the eye and very dangerously increase the eye's leg loads. Bigger isn't always better. - end edit

Mace, the eye of the soft shackle doesn't require a thimble because the 'pin' material is the line of the soft shackle. From an engineering perspective it is a known quantity that won't change so it can be tested and rated. It's actually stronger for not having a thimble.

And, back to the original topic of Pete's thread, any time you can eliminate a link in your winching system is generally a good thing. It's one less item that can fail or come unhooked. Good idea.

 

[opie74]

No offense amigo but you never really got what I was asking.
I was not talking about the winchline itself, I was talking specifically about the eye at the end of the winchline and why thimbles are a good idea on the Eye of the line but not in the soft shackles.

In the end it is not because it would not help, but because the soft shackles design pretty much precludes the ability to mount a thimble (would not be a very soft shackle then). And in real world tesing, they appear to break at the base of the knot anyway.

None taken.

Are you talking about putting the thimble in just the eye of the shackle that goes over the knot? If so, I thought you were talking about using a thimble in the shackle itself, as when one uses it to connect to something.

Assuming you are right in that I just wasnt getting it... Because of the physics involved, the thimble will not make a difference as the eye that goes over the knot will only see half of the ultimate load. This assumes that the shackle is oriented with the eye and knot midway in one of the legs.

The reason I kept bring up a single line rating is because the strength of the shackle is based on a percentage above the single line rating. And how the shackle gets away with no thimble, speaking just in strength, is because the shackle is X times stronger than what it may be attached to, assuming like diameters. The knot dictates the tensile strength, not the eye that goes over the knot and even with derate from minimum bend radius in that eye, the shackle is still stronger than a single line of the same material.

 

[yoopercharged]

Some real physical test data would sure help this post. Smart minds here, but it's really hard to comprehend this stuff without pictures or diagrams.

 

[opie74]

Some real physical test data would sure help this post. Smart minds here, but it's really hard to comprehend this stuff without pictures or diagrams.

I sent 2 shackles to Mill Valley Splicing for certification. Both were constructed identically and made using 7/16 Amsteel Blue. 7/16 has an average tensile strength of 23,900 and a minimum of 21,500. I asked them to rig the shackles using 3/4" pins on both ends and orient the knot/loop at either 9 or 3 o'clock. They pulled to 3 different values I supplied and held for 5 minutes and noted any movement or noise in each specimen prior to releasing the tension. Then each was pulled to failure. They failed at an average well above the single line strength with both failures at the knot.

Here is a video I did showing the operation and proper orientation during use..... Since the video I sent another to them so I could verify some numbers.

[YOUTUBE]3C8ZWRpUNPU[/YOUTUBE]

 

[Southeast Overland]

Some real physical test data would sure help this post. Smart minds here, but it's really hard to comprehend this stuff without pictures or diagrams.

Southeast Overland had numerous 3/8", 7/16", and 1/2" soft shackles load tested. These test results were used to develop our average break strength, along with our WLLs.

We also tried several knots, lengths, and configurations, along with types, widths, number, positioning and attachment of abrasion guard to end up settling on what we felt was the best combination of features and price. For example one knot we tried took much less line which meant we could sell the soft shackle for less $$$, but the downside is the knot was much smaller and we felt the knot wouldn't provide a firm enough attachment point for the loop end - field testing confirmed this. We also tried a much (much) larger knot which provided a great attachment point for the loop end - but - it became very difficult, especially after the soft shackle was heavily loaded, to get the loop end over the huge honkin' knot - it was a good idea in theory that didn't work out in the end.

There also is some nice Kevlar tube webbing on the market that could have been used but before you know it the retail price gets too high and the return on the extra cost just wasn't there in our eyes. Tighter (narrower width) abrasion guard on the soft shackle keeps the abrasion guard from sliding around as much but then you lose the ability to easily reposition the abrasion guard, and the taught abrasion guard (some was very very tight) also limits the ability to as easily open the soft shackle loop, especially when the soft shackle has been heavily loaded and the soft shackle attachment points (where d shackles or similar attach) start to conform to the d shackle. Abrasion guard that was physically attached to the soft shackle with several different methods was tested but we weren't happy with any of the results. We do have one accessory/configuration that we might be adding... still want to test that more...

The Southeast Overland 3/8" soft shackles have a 29,000 average break strength, and a 7,250 WLL at a 4:1 safety factor. The 29,000 lb average break strength is when attached to a minimum 7/8" pin (from a 3/4" shackle). If you wrap that 3/8" soft shackle around a smaller radius bend like on a tube thimble the strength of the soft shackle will be degraded to a degree since the tube thimble will impart a sharper bend than what the 3/8" soft shackle was load tested on.

The 1/2" soft shackle has an average break strength of 42,000 lbs and a working load limit (WLL) of 10,500 lbs at a 4:1 safety factor.

We had all the load tested to failure soft shackles returned for our inspection. I'll get some pictures of the failed soft shackles and post them up here. About 3/4 of the shackles broke at the base of the knot with the remaining 1/4 breaking at the attachment points (where shackles were attached for load testing.)

 

[60Works]

Peteinjp, I think that's a good question; I've been wondering the same thing. With or without a thimbal in the rope loop, a shackle pin is much larger in diameter than any hook eye (hole) and will reduce stress on the rope due to the larger bend radius providing an added safety margin.
Personnally, I think I will use a shackle whenever I can, rather than the hook - unless someone comes up with a good reason not too in this thread.
cp

Aside from abrasion issues, I think eliminating the hook and using a steel shackle is a good idea.

There is, however, a limit to the benefit of using a larger diameter pin. It is important not to 'round out' the eye on a large tube or pintle. The eye should maintain a definite teardrop shape. The angle at the point of the teardrop should be less than 30° or so. A rigid thimble will ensure a safe teardrop is maintained plus protect the eye from abrasion.

I attached two crude diagrams. The first shows how the effects of angle on the loading on the legs of a winch line using a snatch block. The second applies that concept to the legs of a winch line forming an eye. I doubt this is often a problem but it's worth mentioning. I can also imagine a scenario where someone tries to use a tree saver strap around too large a tree or boulder and has too much angle on the legs of the strap at the shackle.

Using a soft shackle has some advantages over steel. Not only is it extremely versatile about what you can tie to, if it does fail there isn't a large steel mass flying back at your windshield, only a few ounces of nylon. If the idea catches on we might see bumper manufacturers putting on rounded anchor points instead of sharp edged holes.