Low Friction Ring strop methods survey

[Seaworthy Lass]

Originally Posted by Breaking Waves

yes, this. webbing results (typically) do NOT simply scale with width. The geometry changes as they get wider - Something about edge to middle ratio I think (higher on narrow, smaller on wider) - thinwater could probably explain the physics better. The geometry of round rope does not change (as much).

OK, that explains it then. Thanks.

I know next to nothing about webbing

[Breaking Waves]

Originally Posted by Seaworthy Lass

ring being retained snuggly, it can be removed from the Bullseye weave

interesting - will have to think about that.

it would never be accepted in a commercial test, because we are stressing the ring well past rated working load, and it might have slightly distorted or weakened and effect subsequent tests in some undetermined/unnoticed way.

If I was there as the tests were being done, as I usually am for commercial pulls, I would be more comfortable; but I am not for these and it would impose a bit on the guys.

[Breaking Waves]

Originally Posted by Seaworthy Lass

Any tips on how to do this easily?

I put the pullers in both ways first, or dyneema threads which I can use to pull the pullers. It's always a tight fit, but it does eventually go.

- It is hard to get good load distribution with multiple loops and it looks so very clunky.

Yea, I will have to look at rope sizing options. using just two loops would be best for load distribution. three can work if you have a good way to pre-tension. 4 starts to be difficult to get the loads equalized.
I am guessing the multi-loops will be least popular of these stronger choices for DIY.

The tapered whipping would be easiest to do all three options. But I have the feeling it may be least popular of the choices among DIYers.

The bullseye and double loops would require a little extra design work for the multi-loop option. Both would be easy for crossed ends and soft shackle.

I have ordered some bits I need, and will think about the samples design.

I just asked the lab about the pin size, and they really prefer to stick with the 3/4". We are guessing we are going up to 15,000lbs or so and they don't like the safety margins on smaller metal than that. We could use textile bend, but I'm just not sure the dynamics are the same as rope to metal - we might be testing something unintended.

breaking waves

[Seaworthy Lass]

Originally Posted by Breaking Waves

interesting - will have to think about that.

it would never be accepted in a commercial test, because we are stressing the ring well past rated working load, and it might have slightly distorted or weakened and effect subsequent tests in some undetermined/unnoticed way.

If I was there as the tests were being done, as I usually am for commercial pulls, I would be more comfortable; but I am not for these and it would impose a bit on the guys.

The Wichard FRX25 LF ring (25 mm hole diameter) I typically use with 5-6 mm UHMWPE rope has a listed working load of 5,000 kg. Breaking load for this ring is not listed, but the ring one size down lists breaking load as being 2.2 x working load for that diameter. So I think breaking load is likely to be 10,000+ kg for the 25 size ring.

The 5mm line I used recently (Stealth Super 12) has a listed break load of 3400 kg.

I think the larger ring won’t be stressed if combined with a smaller diameter and could be reused easily.

Extra work for the lab is the stumbling block though, although if the weave was taped in place so the insertion is unmistakable the changeover would only take seconds.

It would save a substantial amount needing only one ring instead of six for the trial.

SWL

PS When you made up the Bullseye samples did you actually insert the ring during construction rather than afterwards? The weave can be made very tight and the ring can still inserted afterwards.

Edited to add: I went back to my instructions and I see I did not state the ring could be removed at any stage. For some reason I have been making these up lately without the ring in place (it can be done either way). I should re-read my instructions more often .

[Seaworthy Lass]

By the way, the version that connects two rings can only be made if the rings are inserted after the weave is woven. You can see how snug the fit is, yet the rings can be put in and taken out at will (spread the weave apart with a few fingers and while holding it there push the ring through with any spare fingers):

[Breaking Waves]

Originally Posted by Seaworthy Lass

PS When you made up the Bullseye samples did you actually insert the ring during construction rather than afterwards?

yea, during construction. I clamped it and then made the weave around it.

I did just popped the ring out of my spare one, and I see I do have a half twist in both strands.

[Breaking Waves]

Quick thought - Because yachting padeyes seem to have relatively small bails - seems like two opportunities:

seems like someone has an opportunity to sell a 'snap-on bushing' (perhaps out of black nylon) which expands the bend radius of typical pad eyes - for use for dyneema attached clocks and such.

or

using webbing for the low friction ring strop - does not have the same bend radius limitations as rope. You might not want to cow hitch the webbing, and some sort of high load bone might be the best solution. I guess you could also use a shackle - soft or hard to attach.

[Seaworthy Lass]

I have been mulling over this.

It now seems we have absolutely no idea of the strength of a dyneema loop cow hitched onto a bail. Is that correct?

There is also now absolute doubt in my mind if the 85% strength referred to earlier is relative to system strength or line strength. System strength seems more likely (I had been using line strength and now feel pretty stupid ). So seeking stronger options such as using a soft shackle simply on a strength basis may be pointless.

I now suspect the comparison of loop to soft shackle may not be a worthwhile one.

I think the most valuable thing is to first find out what the strength of a dyneema loop cow hitched onto a bail is for a range of bail sizes (cruisers could be using anything from roughly 1:1 to 8:1).

Design would only need to be very simple:
Simply cow hitch the loop onto the test size of bail.
Loop it over the selected LF ring size without any restraint so the system there is not affecting results. Select a LF ring that is not the weak point in the system (with a MBS generously over 200% line strength also means one ring could be reused)
Break it.

This does take some setting up though, something the lab probably won’t want to do. Is there any chance you could be persuaded to set up load testing gear?
There is still so much to be explored with UHMWPE and it is being adopted more widely by cruisers every passing year.

SWL

[Seaworthy Lass]

Edited: scrap this:

Still red faced here.
What a rookie mistake!

I don’t know why I didn’t rethink this after I gained a bit more knowledge. It seems so obvious now . It was as if the figure of 85% line strength was tattooed on my brain for a loop cow hitched on a bail.

Given this, I think the soft shackle and loop strength are likely to be very similar. Certainly not enough difference to justify increasing complexity of making a soft shackle (just as BW has been suggesting is likely) unless you want the short length and/or the ability to detach it with the line in place (which I still like). Also probably not worthwhile all the trouble and cost of comparing in tests if only minor differences are expected.

Breaking Waves, thanks tremendously for this discussion. It has been an invaluable one for me. The light went on after seeing the load test result of the cow hitch on the LF ring.

SWL

[Dsanduril]

Originally Posted by Seaworthy Lass

...

Breaking Waves, thanks tremendously for this discussion. It has been an invaluable one for me. The light went on after seeing the load test result of the cow hitch on the LF ring.

SWL

Actually thanks to everyone. I've been doing my own marlinspike work for decades (more than I like to think about) and try to keep up with modern trends as best I can. I have nothing to contribute other than my thanks, so here they are. BW, SWL, ES, DH, and all the others, your discussions here inform a whole host of others on the sidelines who take your work and employ your techniques. I find the discussions of the details far more informative than any guides from the rope manufacturers or books from the gurus.

Thank you.

[Breaking Waves]

I'm still noodling around waiting for bits and bobs to arrive. I've ordered some 8mm Dyneema webbing (I don't usually use that narrow) to play around with on the rings - because small D/d is one of the prime reasons to use webbing, and some assorted diameter small stuff to try to optimize the tapered whipping. Samson says there is nothing clever in their tow ring whipping - that it is just as it looks.

From the previous test, I personally am curious to strengthen the pin end enough so that we find out when/how something will go bad with the tight eye splices. Understanding this will help me think about thimble design. I thought I understood the general parameters, and I may still because we did not get a break there, but it would be useful to confirm (or not). I occasionally have thimbles/rings custom 3d printed or CAD/CAMed.

And we have identified a seemingly large hole in our data re the cow hitch strength. There are a lot of scenarios which could be explored, but just a simple loop vs cow hitch on one pin size would at least give us a starting point.

BTW SWL, on your soft shackle strop design - occurred to me if you used a Brummel on both sides of the weaving, you would then be free to use the button/buried tail stronger shackle design, which might significantly improve strength (assuming they break at the diamond). You already have one Brummel on the noose side so putting one on the other side should not detract from strength. This would be a bit longer strop.

[Breaking Waves]

for those who have not seen a certified test . . . these graphs are always a bit interesting.

You usually hope for a nice clean break - as the tapered whipping did:



Sometimes it is useful to have a 'fuse with safety' (something which gives a clear sign of excess load but without letting the system break) - which is what happened with the Antal whipping.



The whipping slid down, which is where it relaxed load first. Then the tails pulled out (which should really not happen).

and sometimes see a jerky break, as the cow hitch did - which usually means you need to proof test/pre-tension to near working load these designs to make sure they are set and will not slip/generate heat and shock loading. But in this case, the second jagged point is apparently ring deformation (which you would only know visually).

[Seaworthy Lass]

Originally Posted by Breaking Waves

BTW SWL, on your soft shackle strop design - occurred to me if you used a Brummel on both sides of the weaving, you would then be free to use the button/buried tail stronger shackle design, which might significantly improve strength (assuming they break at the diamond). You already have one Brummel on the noose side so putting one on the other side should not detract from strength. This would be a bit longer strop.

I experimented with that a few years ago .

A button stopper works fine, but the significantly longer strop is a big issue for me. The eye is generally the end that needs to go around the bail (a knot won’t fit) so rather than the button being when the second Brummel is made, it needs to be 30x line diameter away to allow to the bury (same would go for a toggle). That is another 15 cm longer (plus the Brummel) if 5 mm line is used.

I also tried Starzinger’s overhand knot with spliced loops without a second Brummel, as there is only a tiny amount of bury sticking out. I actually wrote Dockhead instructions for this knowing he used this knot in his soft shackles. The problem I found though was that it was difficult to get the two inner legs exactly the same length and I felt this would reduce strength, defeating the purpose of the exercise.

Unlike ordinary soft shackles where I use Brion Toss’s button stopper almost exclusively (I love the handling and the aesthetics and the extra strength is great for connecting snubber to chain where the gap limits line diameter), I finally decided this is one instance where if you want 30% extra strength, you simply bump up line diameter. For me a short strop (or in the case of the last three I made, medium sized for the purpose) is the greater priority.

SWL

[Seaworthy Lass]

Originally Posted by Breaking Waves

I'm still noodling around waiting for bits and bobs to arrive. I've ordered some 8mm Dyneema webbing (I don't usually use that narrow) to play around with on the rings - because small D/d is one of the prime reasons to use webbing, and some assorted diameter small stuff to try to optimize the tapered whipping. Samson says there is nothing clever in their tow ring whipping - that it is just as it looks.

From the previous test, I personally am curious to strengthen the pin end enough so that we find out when/how something will go bad with the tight eye splices.

I have never seen these loops anything other than cow hitched on. A 1:1 bail:line diameter could possibly then be used with only a small % decrease in strength (testing the cow hitch would determine the %).

Do a significant number cruisers/sailers use these loops with a bail that has a pin, necessitating a stronger design for this usage?

Originally Posted by Breaking Waves

Understanding this will help me think about thimble design. I thought I understood the general parameters, and I may still because we did not get a break there, but it would be useful to confirm (or not). I occasionally have thimbles/rings custom 3d printed or CAD/CAMed.

It would be great to have a “ring” design (it would no longer be a simple ring) that would enable the “ring” to be captured easily without bumping up the cost. There are a few options on the market, but either made only in smaller sizes, or significantly more expensive. One huge advantage with current simple LF rings is the relatively low cost, so I think anything new on the market would need to be able to compete favourably with the price of these to gain a reasonable market share.

SWL

[Breaking Waves]

Originally Posted by Seaworthy Lass

I have never seen these loops anything other than cow hitched on.

Do a significant number cruisers/sailers use these loops with a bail that has a pin, necessitating a stronger design for this usage?

My personal interest is not particularly related to lfr usage, but rather learning about high angle spliced loop strength parameters, which will only happen if I make the samples relatively strong enough at the pin end that the loops/splice end breaks in the testing.

I could do this more easily - but just using a 'single strand' strop (not a loop) with high angle splice to LFR one end, and spliced loop (100% strength) to pin other end. That would certainly break at the LFR end. But we would miss the opportunity to learn more about alternative/stronger LFR strop strength.

Milling and printing low friction thimble shapes is not hard nor expensive, except for capital cost (of the machinery). The capital costs would probably kill it as a commercial product, but as an occasional item for someone who has the machinery for other bigger usages it has pretty low incremental costs.