Low Friction Ring strop methods survey

[thinwater]

Originally Posted by Seaworthy Lass

...Not when it comes to snubbers. I think most cruisers are pretty good at considering dynamic loading then .

Actually, no.


The rate of loading on snubbers falls within the static test range. Same when people consider "impact" load on chain and bring up the brittleness myth.


The actual loading rate where dynamic effects and brittleness become relevant is a hammer blow, not some thing that happens over a second or more.


Impact loads on slack steel shrouds or safety tethers are better examples.

[Breaking Waves]

OK, second test results.
Not exactly what I expected, will need to think a bit, but here is the raw data:

Strongest – these two the same
A Webbing – 10,500lbs – 346%, of web strength – this is doubled pre-sewn 8mm climbing webbing loop
One strand broke at top of ring
This is obviously a pretty good solution - dead easy

B Flat whipping – 9778lbs – 195%
Broke on the ring (where the tapered bury was)
Both ‘looped’ and ‘cow-hitched’ broke the same
My overlapped tapered bury was not as strong as I expected - seems like I needed more bury overlap (Which would not be to hard)
But I also get the sense looking over all these results in the test that with all these 'doubled strand loops' there is significant loss due to unequal loading. I tried to be careful, but I did make them entirely by hand (As any DIYer would), without any sort of mechanical tension equalization.

2ND place – these two the same
A Long double loop – 8330lbs – 154%
Broke at pin (which is where bury was), cow hitched samples broke at pin 8% lower
Not much strength loss from cow hitch - but there are other factors here which complicate the finding
I had expected this one and the above-tapered whipping to get over 200% - I guess need longer overlapped bury, and better strand equalization, to accomplish that.
BUT why this is weaker than the spliced loops in prior test - I have no idea.

B Short double loops – 8522 lbs – 157%
Broke at pin, cow hitched sample broke at 4% lower
These short loops had an 85% throat angle – the very tightest I could make.
Surprising - I intentionally made these as high angle as I could and the throats visually looked 'stretched wide'

3RD place
Soft shackle with bullseye - 7504lbs – 140%
Broke at base of knot

No ring distortion noted in any samples.

[Breaking Waves]

Lab has commented for the two splices loop sample sets, the breaks were not 'clean' - eg in most of them only 8 out of 12 strands broke and in none did all 12 strands break. This is a usual sign of the load/lengths not being well equalized.

So, in fact by making these a bit more complicated than last time (trying to beef up the pin end), I actually made them weaker by making the strand equalization harder.

They also commented that this would all be easier/better if I allowed the strops to be longer - makes equalizations easier.

They made a 3' long sample, with their best technique, which went to 12,000lbs (Note: using 12% stronger rope). So was better, but not a huge gap. Feel we did pretty well given I had taken short strop as an application requirement.

[Breaking Waves]

Like I had earlier in SWL's thread, they commented a button with bury would make the soft shackle version stronger - but I guess would probably require a brummel or whipping on the stopper knot side.

[Seaworthy Lass]

Originally Posted by Breaking Waves

3RD place
Soft shackle with bullseye - 7504lbs – 140%
Broke at base of knot

Breaking Waves, many thanks for including the Bullseye weave with the other samples. The weave has not been load tested since developed three years ago.

My prediction then (and Starzinger’s too) was that the diamond knot would be the limitation. Your testing has now shown this is indeed the case, although not at the 170% usually seen when this knot is incorporated in a soft shackle, as I expected. I am not unhappy with 140% though, as the prime reason I use this strop is for its short length (it can be made even shorter than your sample) and the fact it is removable with the line passing through the ring.

Yes, the design can certainly be strengthened with buried tails at the stopper end, but then the advantage of the very short length would be lost. Whoever is making these up can choose for themselves .

This was the discussion three years ago:

Originally Posted by estarzinger

Correct - I would rate it conservatively at 150% of the dyneema strength. If you used a 'stronger approach' (eg with the tails buried) you move the weak point to the neck and raise the strength to around 220%.

SWL

[Breaking Waves]

^^

I’m thinking 140/150% range would be reasonably typical for a diy diamond. They can go higher, but I guess that requires both recently making a bunch of them (just so you have it all down perfect) and some extra careful tensioning thru the process (including a careful take up of the knot itself). I have not made a diamond in quite a while, and I did not do anything special in making this one, just tied it up and make it tight. So, I guess reasonably representative of a typical construction. Don’t know anything about them, but this quick google would seem to agree http://www.balancecommunity.com/slac...ackle-methods/ You might well do better.

I do agree their movability is a nice aspect. And with right size line would be more than strong enough, as just regular diamond soft shackles are.

On the spliced samples - I guess this test reinforced the conclusion that the main ring end constructions are all pretty fine and the key is a reminder to take good care in the splicing basics - good bury/good taper/good strand equalization. I probably was too focused on the ring end and fancy details and not careful enough on the splice basics.

And the webbing result are interesting. Suggest they should be given greater consideration. Less work to construct and less risk of diy getting it wrong and not expensive.

[Breaking Waves]

I asked the lab about the cow hitch. Below is their comment. Basically they don’t see it at all in their commercial work.

“I have no experience in the cow hitch but it seemed to act a lot better around the 3/4" pin. With more of the rope seeing the pin surface the load is not so great in one area. With that being said. the cow hitch on the ring will definitely deform the ring because of the choking that happens. Although there were no real differences in the cow hitch to the straight loop. I would say the cow hitch acted better.”

[Seaworthy Lass]

Originally Posted by Breaking Waves

^^

I’m thinking 140/150% range would be reasonably typical for a diy diamond. They can go higher, but I guess that requires both recently making a bunch of them (just so you have it all down perfect) and some extra careful tensioning thru the process (including a careful take up of the knot itself). I have not made a diamond in quite a while, and I did not do anything special in making this one, just tied it up and make it tight. So, I guess reasonably representative of a typical construction. Don’t know anything about them, but this quick google would seem to agree A comparison of Soft Shackle methods | Slack Science You might well do better.

Balance community’s assessment of diamond strength being 146% line strength is certainly in line with your latest results, so I think even if a higher % may be achieved with careful construction, the more conservative lower figure is clearly the better one to rely on.

By the way, did you see their photo of a Button stopper? They say “This is the method we use for our professionally made Soft Shackles in the shop”, but it is the weirdest looking Button I have ever seen!

SWL

This is Balance Community’s image of a Button stopper:

[Breaking Waves]

I had not scrolled down. Yea that is a bit weird. I wonder if that’s what happens if you pull/load on a closed shackle while the button is real loose - does it “self dress” to that?

I've not made either of these stoppers in a while, gotten out of the swing of them.

I was involved (very distantly) in a project which was trying to design a more compact stopper by weaving the 12 strands (rather than knotting) - a 12 strand button. They wanted to try the soft shackle idea on bigger rope, but the normal diamond and button grow to be huge and they wanted something sleeker. I had thought they should use a toggle or bone but they were looking for a sleek symmetrical textile solution. Not sure what they ended up with.

[Breaking Waves]

In any case, I feel like we covered some good ground regards LFR’s.

The cow hitch question still seems unanswered.

[Dockhead]

Originally Posted by Seaworthy Lass

Balance community’s assessment of diamond strength being 146% line strength is certainly in line with your latest results, so I think even if a higher % may be achieved with careful construction, the more conservative lower figure is clearly the better one to rely on.

By the way, did you see their photo of a Button stopper? They say “This is the method we use for our professionally made Soft Shackles in the shop”, but it is the weirdest looking Button I have ever seen!

SWL

This is Balance Community’s image of a Button stopper:

That's an ugly button knot.


I still have a couple of your Mk. 1 soft shackles from when soft shackles were still exotic; from when you sent them to me God knows how many years ago -- the button knots are works of art One of them attaches my staysail sheet to the staysail clew and quick release for using the same sheet as an inf**ker for my jib twings.



I make my shackles using Evans Starzinger's "improved soft shackle" design, which have double collapsed Brummels instead of any knot at all. They are a snap to make, not as pretty as a good button knot (but far better than this example), and hella strong. They look like that one except for the knot. I use them in all kinds of high load applications, like jib sheet to clew attachment, halyard extensions, etc. Nary a problem. Love 'em. The design unfortunately is no longer on his site, but that's why God made WaybackMachine


I expected to need to change them every year or two, but they show no signs of wear or deterioration whatsoever, other than some sun fading.

[fxykty]

Originally Posted by Dockhead

That's an ugly button knot.


I still have a couple of your Mk. 1 soft shackles from when soft shackles were still exotic; from when you sent them to me God knows how many years ago -- the button knots are works of art One of them attaches my staysail sheet to the staysail clew and quick release for using the same sheet as an inf**ker for my jib twings.



I make my shackles using Evans Starzinger's "improved soft shackle" design, which have double collapsed Brummels instead of any knot at all. They are a snap to make, not as pretty as a good button knot (but far better than this example), and hella strong. They look like that one except for the knot. I use them in all kinds of high load applications, like jib sheet to clew attachment, halyard extensions, etc. Nary a problem. Love 'em. The design unfortunately is no longer on his site, but that's why God made WaybackMachine


I expected to need to change them every year or two, but they show no signs of wear or deterioration whatsoever, other than some sun fading.

Apparently the sun fading on the outside of UHMWPE rope does not weaken it as it affects only the very outer fibres and protects the rest of the fibres even better than when new. How many strands would need to be fatally damaged before the rope strength drops to 75% or 50% of the original?

[Dockhead]

Originally Posted by fxykty

Apparently the sun fading on the outside of UHMWPE rope does not weaken it as it affects only the very outer fibres and protects the rest of the fibres even better than when new. How many strands would need to be fatally damaged before the rope strength drops to 75% or 50% of the original?

I really wouldn't know. My soft shackles are all far stronger than whatever they are attached to, so it's a moot question for me.

[Breaking Waves]

I'm stubborn

I really think I should be able to hit 15,000 lbs - frustrated actually that it is taking me 3 rounds to possibly do so.

The lab has agreed to do another break cycle for me.

I am just going to submit one design, with good D/d on pin end learned from round 1, and good strand self - equalization under load learned from round 2.

Here is what it looks like:



Had a little fun with the whipping color. Did a bit longer bury's and finer tapers, simple bury's with no complicated overlaps, & looser whipping. They suggested I not lock stitch, and there is a 'semi-lock' structure at the cross-over, but I did stitch because it just does not feel right without.

The lab for their own interest asked me to make up a couple webbing variation. They were quite interested in that result, can see some extra potential webbing applications, but want to be sure it is repeatable/dependable.

And they have asked me for a length of the rope I have been using for the strops - going to try to make one of their own up to beat this one of mine.

A friendly competition is always good for development

[Breaking Waves]

Originally Posted by fxykty

Apparently the sun fading on the outside of UHMWPE rope does not weaken it as it affects only the very outer fibres and protects the rest of the fibres even better than when new. How many strands would need to be fatally damaged before the rope strength drops to 75% or 50% of the original?

Not sure who is saying this - but not true.

UV very definitely weakens Dyneema rope, by round numbers 50% (I have seen tests with results ranging from 40% to 70% - depends on size/braid and coatings) over 24 months (in semi-tropics).



This HAS been tested quite extensively because it is of high interest for the commercial users. It very definitely degrades.