Unveiling Bullseye Strops for low friction rings

[Seaworthy Lass]

Originally Posted by Amsteelbluez

I am looking to make a couple soft shackles with 3/16 Amsteel Blue and a 14mm LFR. The user wants the shackke portion to be short, 2.5" length, without knot. Seems very short for 3/16? I have a 7/64 shackle at 3" and it fits real snug over my pinky.

You mentioned the right one for the eight application and some can be made extra short. Which one would that be? Does the ring come off easily or stay in place for good?

Thanks

All the photos in the post you quoted don’t snuggly hold a LFR. Most of the rest of the post discusses soft shackles in general, not ones specifically meant to snuggly hold a low friction ring.

In my opinion the best way of snuggly securing a LFR with a relatively short soft shackle is by using the Bullseye design (instructions from post # 43 onwards).

The snag is that the groove in the perimeter of the LFR you are using (14 mm inner hole size) is too small to hold 2 lots of line, which is needed to make the Bullseye design. You would need to either decrease the diameter of the line or increase the ring size.

The minimum size is determined by how much length you need to easily open the eye to pass the stopper through. 2.5” seems too small for me if you are using 3/6” UHMWPE.

SWL

[Breaking Waves]

Originally Posted by Amsteelbluez

The user wants the shackke portion to be short, 2.5" length, without knot.

This may not help you since you are trying to sell soft shackles . . . . but you might tell your customer that the best way to attached a lfr so 'short' is generally with a lashing - strong & easy to do, and it can be moved if necessary. The soft shackle approach is really only needed here if it needs to be moved very frequently/quickly like a snatch block.

........

[Amsteelbluez]

I asked what it will be used for and he said for the an inhaul (barberhauler) for jib sheet. Would this use be acceptable and safe?

doing some reading now

EDIT

Found this on sailing anarchy forum. Sounds like maybe he's aiming for something like this?:

The ring and car is my adjustable jib/genoa "block", just replaced a bearinged block with a low friction ring. The white line is the sheet, the yellow and white line (Apex) is a 3:1 genoa car adjustment line.

[Breaking Waves]

Originally Posted by Amsteelbluez

inhaul (barberhauler) for jib sheet. Would this use be acceptable and safe?

sure, no problem.

That is not moved very much, and personally, I would think a lashing would be superior.

But the bullseye will also work just fine, is a good design.

[Jammer]

I am experimenting with these for the rig for my Chameleon dinghy.


I can see that the width of the outer groove in the ring is a critical dimension and should be enough to allow the legs to sit side-by-side.


I am not sure that having the two legs be the same length is as critical as made out to be in the instructions, for the soft shackle version, because all it does is change the size of the openable eye. I felt that I was able to get it right without measuring and fussing.


Photos show 1/4" and 7/64" Amsteel.


I will probably use smaller rings and use 7/64" for the strop. I got the larger rings with the idea that the larger radius would reduce friction but they seem disproportionate.


Anyway, it's a useful lashing, thanks for sharing it.

[Les Noble]

Awesome solution, just what I was looking for. I don't know how the self taking rig was setup for the staysl originally, but couldn't run a single tacking line forward and back because of the dinghy on deck. This would have pulled the clew forward anyway and always a belly. Wasn't seeing a solution up and down the mast either.
Not completely self tacking now, but we will see. Sea trials commence!

[dlymn]

Check out this video about making a shackle with a dogbone. Now imagine a low friction ring in the place of the dogbone. OK, so 2 "bits" of dyneema around the ring then the ends woven across and then buried into the braid. No whipping require, maybe a bit of sewing. The made shackle is great.
https://youtu.be/C2kJxtrn36Q

[Albcn]

Originally Posted by Seaworthy Lass

I was looking at a few shots of low friction rings in use and found a pair lashed together in a photo Dockhead took on a racing Swan recently.

This is a close up:




It must be very difficult to distribute the load evenly with lashing like this, weakening the system.

The Bullseye weave can be used in this application as well.

Make a loop and twirl it around two rings to join them very snuggly together. Here I used 4 mm dyneema end to end spliced with a 72x line diameter bury tapered over the last quarter of the bury.
Predicted breaking load of this is a whopping 8000 kg! if the line strength is 2000 kg for the 4mm dyneema used.

EDITED TO ADD:
I have a better grasp now of how system strength can reduce in situations like this, so the original estimate of 8000kg I made above is incorrect. Losses in strength will occur for the reasons listed below. I think these losses are not cumulative, so the biggest one simply overrides the rest.

1. Although the throat angle here does not create any "peeling" force (no side load at the crossing), the angle of deviation of the line from the primary angle of pull will reduce strength.
The formula I have come up with for system strength efficiency due to this
= cos (throat angle / 2) x 100%.
The throat angle you would use is the greatest one in the system, as this is what will be limiting things.
I put a protractor on the photo and estimated the greatest throat angle. This seems to be around 60°.
So estimated system strength efficiency = cos (60/2) x 100 % = 87%

2. Bending losses will also occur. The diameter of the dyneema (d) compared to the diameter of the portion of the LF ring it is going around (D) need to be taken into account. In the example here the diameter of the line is 4mm and the ring 35mm therefore D/d = 8.75.
From the graph given in Evans's load testing document, the system efficiency is therefore around 83% due to the bend around the ring.

3. Losses in strength will also occur due to compression and bending of the dyneema at the crossings. Evans Starzinger has pointed this out a few times in both this thread and the one on Antal whipping. Also Brion Toss has said:
"Although fantastically strong in tension HM fibers are quite weak in compression. Since knots invariably compress the rope under load, it is clear why knots typically weaken HM rope by at least 70%."
The losses here due to compression are not known, but I think are unlikely to be anything similar to actually knotting the dyneema.

So, if the above is correct (any structural engineers here that could confirm this?), then the system efficiency is being reduced primarily by the bending of the dyneema going around the ring, therefore it would be around 83%.

So system strength here would roughly = 4x 2000 x 83% kg = 6640 kg
Still a whopping amount .


The rings can still be removed, but only with a fair bit of difficulty (bring the rings together, tip one towards the other, pull on one of the loops going around one ring and eventually one loop can be forced over):

DIAMOND TWIN RING STROP:

Hi Seaworthy Lass!!
I recently found this thread. It´s a beautiful way to use friction rings.
I can´t imagine how to do the DIAMOND TWIN RING STROP.
Could you post a diagram?
Thank you!!

[rgleason]

32' Sloop, 86% jib. I'd like to make a good barber haul (pulling in to centerline) solution for a 86% jib that sheets forward of the lower forward shroud. We have adjustable (from cockpit) sliding track on the rails. I'd like to pull the jib towards the centerline as far as possible given the shrouds location (about 6-7") to improve the sheeting angle. I would like to be able to set the barberhaul for both sides with one line and leave it while tacking. I would like to be able to remove the barberhaul fitting from the sheets when reaching, running or going forward.

I was considering a simple 1/2" center line with jamb cleat under the dodger, splitting into two lines through two eyes at the D ring for the vang. Then going to some fitting on the 1/2" jib sheets. I feel like I want that fitting to be removable. What should I use? A climbing carabineer attached to an eye so that I can have a 2 part barberhaul?

The jib is about 187sf. What type and size of line should I use and what size thimbles, etc.? So I can do this once.

[s/v Jedi]

The possibilities with Dyneema and LFR’s are endless. For self tacking jibs I think you can replace the whole track and car thing on the foredeck with two pad eyes, a length of Dyneema spliced between them with a LFR ring sliding along.

People are still very attached to hardware, shiny things to mount to their boats but an ever larger group looks for ways to eliminate it all.

My Laser dinghy had a rope traveler.

[Seaworthy Lass]

Hi Albcn
Welcome to CF.
Thanks for the compliment .
I have been using the Bullseye weave now for at least 6 years to hold low friction rings and this easy technique has worked flawlessly.

I have attached a photo of how a simple loop can be twirled around to create the weave.

The ideal sized line is small enough in diameter so that 2 lots can sit comfortably in the outer groove of each ring.

The easiest way to construct this is to start with a straight bit of line and follow the pattern around, keeping the line itself untwisted as it goes around. Then place the rings in and cinch up the line until it is just right. This position has some leeway, but if it is way too tight then you won’t be able to get the rings out, and if it is way too loose then there is a risk a ring may dislodge when used if there is any flogging.

Leave the tails long enough to bury them later (ideally around 70x line diameter, but going down to 40x would probably be sufficient for most uses), mark the join with a marking pen, firmly hold the join and remove the rings. If you give it a shake the weave will untwirl and you will be left with a loop. If you have created the original weave with the line weaving around without any twists, the line within the loop will actually have a twist in it. Do not disrupt this. Taking this bit of care is not super important, but it will maximise the strength.

Widen the marked join to lengthen the loop a bit as the final length will shrink following the bury of the tails Tape the join together until you are ready to bury the ends. Do this as you would any long bury splice (ie taper ends etc). It is then easy to reconstruct the weave if you use the below photo as a guide again.

If anything is unclear I will tray and elaborate.

SWL

[Albcn]

Wow I have seen the light!!
This solution is absolutely brilliant.
I will try it in my boat.
Thanks a lot for sharing.

[fxykty]

Originally Posted by s/v Jedi

The possibilities with Dyneema and LFR’s are endless. For self tacking jibs I think you can replace the whole track and car thing on the foredeck with two pad eyes, a length of Dyneema spliced between them with a LFR ring sliding along.



People are still very attached to hardware, shiny things to mount to their boats but an ever larger group looks for ways to eliminate it all.



My Laser dinghy had a rope traveler.

I would love to do that for our self-tacking jib - removing the track and two cars would be about 8kg. But, the sheeting angle is nearly vertical (82*), the calculated sheet load about 2000kg, and the clew height above the track 480mm. To replace the track with a strop would need HUGE strength that I’m not sure would be possible. Bummer.

[s/v Jedi]

Originally Posted by fxykty

I would love to do that for our self-tacking jib - removing the track and two cars would be about 8kg. But, the sheeting angle is nearly vertical (82*), the calculated sheet load about 2000kg, and the clew height above the track 480mm. To replace the track with a strop would need HUGE strength that I’m not sure would be possible. Bummer.

Use a twing or tweaker? There must be a way