Down and Dirty Dyneema Strops

[CAELESTIS]

Have you considered using this method for securing the ring?

https://www.youtube.com/watch?v=4WW7Qvg3VjI

. Then make a large loop in the other end for the cow hitch/luggage tag?

[Seaworthy Lass]

Originally Posted by CAELESTIS

Have you considered using this method for securing the ring?

. Then make a large loop in the other end for the cow hitch/luggage tag?

The problem with a Brummel lock to secure the ring is that it needs to be close to the ring to be effective and the leg of the loop then kinks badly at the junction. Under load it of course tries to straighten, stressing this point.
EStarzinger found a narrow throat like this reduces the strength of the strop by about 20%.

This may not matter if the chosen diameter of dyneema is overkill for the purpose, but thicker diameter means a longer strop, which may be unwanted.

Also, if a particulalry short strop is needed, doubling up the loop is the best method and the Brummel lock is not possible then. The ring, however, still needs to be secured.

SWL

[Seaworthy Lass]

Caelestis, the methods I have come across for securing the low tension ring in the loop of dyneema are:

- Brummel block (reduces the strop strength by about 20%)
- Velcro
- Heat shrink
- Leather (suggested by EStarzinger)
- A "lock" in the loop of dyneema around the ring (wind the dyneema around the ring, burying the top half of the wind)
- Simple whipping, as Dockhead used initially here (even if the whipping held, there is of stress in the Dyneema and strop strength would be weakened)
- "Benzel" seizing, as CruisingScotts showed in this thread
- Beautifully decorative trapezoid shaped rope work (needs skill and would be very time consuming)

One other solution is to put the loop straight through the very centre of the ring where the other line/lines will run.

A soft shackle could also be used as a strop, but the ring still needs to be restrained somehow.

All the above methods have their drawbacks, hence the search for a simple effective solution.

SWL

PS Anyone come across any other methods?



This is the technique for the "3 minute" binding:

Start by tying a cow hitch on each leg of the dyneema.
This works well to grip the legs a bit and should prevent the loop slipping up over the top.
Once tied, slide the ring in, push the hitches so they are closer to the ring and adjust the separation of the 2 hitches so that the legs continue from the ring on a straight path:




This stage onwards would be tied with the ring in place, but then the cord is not visible, so I am showing this without the ring.
Simply cross the ends of the cord over next to the cow hitches and pass each end around the ring:




Make sure the cord sits under the dyneema all the way around.
Tie a reef knot (or maybe 1.5 reef knots so the structure is maintained), not pulling enough pulling to move the separation between the hitches.




Lock the reef knot with an overhand "stopper", trim the ends a bit (not shown) and seal with a gas lighter:




This is how it looks when finished.
I think the initial bit works very well. There must be a better solution to the reef knot with overhand stopper though, but it eludes me. I need to search through the ABOK. Any suggestions from anyone?
The knot needs to cinch the cord tightly around the ring and it needs to bind together well so it cannot be shaken loose in time.

[Cruisingscotts]

I read through a fair bit of the SA thread, not all 2000 posts but as much as I could without glossing over. And checked out both Allen and Beth and Evan pages. Something that strikes me is the relation to lowfriction ring SWL, the size of dynemma or spectra that will fit in a given ring single or double or etc. and the actual load the application will see. It seems like the biggest use is in sheet lead car replacment and barbor hauler setups. Also static load applications like running backs. I went all in on the concept and have replaced pretty much everything other than multi purchase block arrangments and most of my halyards, I like to expierament. The biggest issue I have had so far is flogging when short tacking. Everything other than the barbor haulers are very short, more like a stand up block and seized similar to the previously posted pic. Due to the low cost of the rings, goign with the largest ring practical and using a smaller diameter strop doubled or trippled for a short length attachment seems so bring the net SWL well above max application load even with less than ideal bend radius's. So the long winded question is how are people using the low friction rings and what sytem for sizing is being used? Particularly in a strop with a large radius ring that is secured in a ideal sitation like SL has shown how is the other end attached? If its rolling around the radius of a shackle or pad eye isn't that going to be the weak point no matter what is done on the other end?

[estarzinger]

Originally Posted by Seaworthy Lass

There must be a better solution to the reef knot with overhand stopper though, but it eludes me. I need to search through the ABOK. Any suggestions from anyone?
The knot needs to cinch the cord tightly around the ring and it needs to bind together well so it cannot be shaken loose in time.

I surprised you are not trying to work the zep in here I thought that was your first love )

I like this approach. It seems to meet the knot tying edict to "tie correctly not more".

As you know, on most whipping the ends are cinched under the whipping - I a possibility along this line is if you brought the ends each under a cow hitch and then put a stopper on it (to prevent it from being able to come back up/out)? alternately you could constrictor knot them to the strands below the cow hitch. You could make this more secure my using more constrictor constructions rather than the cow hitches

You could bring them down thru the cow hitches and then tie the two ends together below, using a zep perhaps - that approach gives you a bit more room and might (Im not sure) allow more bend options (like the zep) to be used. This would have to be the same length or slightly longer than the main connector join between the two strands.

second thought - you should not have any problem with sewing the whipping ends together - no load - right? You could do that at the top or the bottom of the ring. That would be secure and very low bulk - you could do a loose 'multi-purchase stitch" between the two strands and then pull it tight and tie the thread off - but I know you have an aversion to sewing

third thought - you could take the ends thru the main dyneema strands once or twice and put stoppers on. That would be secure and clean and easy, but would entail a small stress riser strength loss (but certainly less than the strength loss from a possible cow hitch on the other end of the strop)

Those are some quick thoughts/options.

[Seaworthy Lass]

Originally Posted by estarzinger

I surprised you are not trying to work the zep in here I thought that was your first love )

I like this approach. It seems to meet the knot tying edict to "tie correctly not more".

LOL! I did try and work the Zep in .

Thanks for the input. I think we should be able to come up with something good.

The usage of these low friction rings will escalate soon and there are lots of people that don't have the inclination or skills to be doing anything complex, so it would good to find a solution that is functionally close to ideal, but quick and easy to do and would work on single or double loops of dyneema and whether or not the dyneema had the bury splice passing through in this area.

Originally Posted by estarzinger

As you know, on most whipping the ends are cinched under the whipping - I a possibility along this line is if you brought the ends each under a cow hitch and then put a stopper on it (to prevent it from being able to come back up/out)?

Yes, that would work, but I think this looks messy (worse than just one stopper hanging out of the middle). It is less secure too as it is further away from the reef knot that it is protecting.

Originally Posted by estarzinger

alternately you could constrictor knot them to the strands below the cow hitch. You could make this more secure my using more constrictor constructions rather than the cow hitches

Do you mean the dyneema strands? No, I don't like the thought at all of whipping twine cutting into the dyneema.

Originally Posted by estarzinger

You could bring them down thru the cow hitches and then tie the two ends together below, using a zep perhaps - that approach gives you a bit more room and might (Im not sure) allow more bend options (like the zep) to be used. This would have to be the same length or slightly longer than the main connector join between the two strands.

The direction of pull would mean the cow hitches were being pulled open. I know there not much force on them, but whatever was done centrally would be working against them and they are functioning really well here to grip the dyneema just the right amount.

Originally Posted by estarzinger

second thought - you should not have any problem with sewing the whipping ends together - no load - right? You could do that at the top or the bottom of the ring. That would be secure and very low bulk - you could do a loose 'multi-purchase stitch" between the two strands and then pull it tight and tie the thread off - but I know you have an aversion to sewing

A constrictor at the top of the ring would function very well I think. It would have no tendency to want to work free in this location. It could be loosely tied with whipping twine when the ends of the cord where brought around the top of the low tension ring, then tightened once the cord was pulled down firmly. The dyneema loop would hide this and protect it.

What may then work well is incorporating your idea above of feeding the strands through the cow hitches. I would just leave half an inch and cut them off then.
This may be a winner. I will have a play.

Originally Posted by estarzinger

third thought - you could take the ends thru the main dyneema strands once or twice and put stoppers on. That would be secure and clean and easy, but would entail a small stress riser strength loss (but certainly less than the strength loss from a possible cow hitch on the other end of the strop)

Not keen on this. Looks messy with stopper knots poking out the sides. Passing the cord back between the legs again, then tying the stoppers would solve this, but I think it is still messy with two stoppers perpendicular to the dyneema.
No advantage over a central overhand stopper either, except the natural angle of the ends emerging from the reef knot is maintained.


On a seperate issue:

The bind works much better without the crossover I put in after the cow hitches. This pushes the cow hitches way up high closer to the max ring diameter, so it needs minimal care to get the separation correct so the dyneema legs of the loop are not kinked. I was fixated on what I found had worked best for the laced binding and had not experimented . Try it without the crossing and you will see what I mean.

SWL

[Seaworthy Lass]

Originally Posted by Seaworthy Lass

A constrictor at the top of the ring would function very well I think. It would have no tendency to want to work free in this location. It could be loosely tied with whipping twine when the ends of the cord where brought around the top of the low tension ring, then tightened once the cord was pulled down firmly. The dyneema loop would hide this and protect it.

What may then work well is incorporating your idea above of feeding the strands through the cow hitches. I would just leave half an inch and cut them off then.
This may be a winner. I will have a play.

........
On a seperate issue:

The bind works much better without the crossover I put in after the cow hitches. This pushes the cow hitches way up high closer to the max ring diameter, so it needs minimal care to get the separation correct so the dyneema legs of the loop are not kinked. I was fixated on what I found had worked best for the laced binding and had not experimented . Try it without the crossing and you will see what I mean.

Hey, this combo works super well .

So well in fact, that the constrictor in whipping twine at the top may be unnecessary. Only testing this out in action would tell us.

Dockhead, I know you weren't keen on trying the "3 minute" bind, but it is a little gem, particularly with the modifications.

I have a really, really good idea . You could cut off the lacing on one of the strops you tied yesterday and tie this instead and test it out for us .
Just kidding, I will try it on something like our yankee sheet and see how it functions.

SWL

[Dockhead]

Originally Posted by Seaworthy Lass

Hey, this combo works super well .

So well in fact, that the constrictor in whipping twine at the top may be unnecessary. Only testing this out in action would tell us.

Dockhead, I know you weren't keen on trying the "3 minute" bind, but it is a little gem, particularly with the modifications.

I have a really, really good idea . You could cut off the lacing on one of the strops you tied yesterday and tie this instead and test it out for us .
Just kidding, I will try it on something like our yankee sheet and see how it functions.

SWL

Well, we'll see. I like the last ones I've tied with your pattern of lacing. They are not laborious to tie up, and now that I figured out (with your help) how to regulate the tension, they even look fairly neat (no one will believe that it's my ropework ). The question is whether the knots will hold, but they should be under little to no stress so I don't see why they wouldn't. I added a half hitch as you suggested.

I think the key is to insulate the knots from the periodic expanding pressure when the strops are under load.

If they work loose, then I'll think about something else. But what I DON'T like about the shorty "3 minute" tie-up you are talking about now, is that you lose the damping effect of all the lacing. Last year I tried something almost identical to your first version of this, and it failed very quickly.

[Seaworthy Lass]

Originally Posted by Dockhead

Well, we'll see. I like the last ones I've tied with your pattern of lacing. They are not laborious to tie up, and now that I figured out (with your help) how to regulate the tension, they even look fairly neat (no one will believe that it's my ropework ). The question is whether the knots will hold, but they should be under little to no stress so I don't see why they wouldn't. I added a half hitch as you suggested.

Over hand stopper, not half hitch . Or add a couple of constrictor knots with whipping twine. I think the sloping lacing will work well if the reef knot is just secured better and I doubt even a half hitch will do this long term. Hope to be proved wrong.

Originally Posted by Dockhead

I think the key is to insulate the knots from the periodic expanding pressure when the strops are under load.

If they work loose, then I'll think about something else. But what I DON'T like about the shorty "3 minute" tie-up you are talking about now, is that you lose the damping effect of all the lacing. Last year I tried something almost identical to your first version of this, and it failed very quickly.

That is useful info. Even tiny modifications can alter the effectiveness tremendously though. I may be way off base, but the "3 minute" bind just feels right to me, even though I recognise the forces at play. The new version works even better, as the combo works synergistically.

I have taken photos and will go load them.

Having a nice sail?

SWL

[Seaworthy Lass]

Top and side views.
Dockhead, I know it looks unbelievably simple, but I just have a good gut feeling about it:








Edited to add:
Following Dockhead's concerns about it working loose, the cut ends in this next shot could be left a bit longer and another constrictor tied with whipping. Combinined with the constrictor on the top, I doubt anything would shift this binding then:

[Dockhead]

Originally Posted by Seaworthy Lass

Top and side views.
Dockhead, I know it looks unbelievably simple, but I just have a good gut feeling about it:

Well, someone should try them out. The wide throat angle might be the saving grace -- this reduces the "pumping" action which undid my ones from last year, maybe eliminates it. But the small number of wraps increases in any case the risk that the construction gets skewed, which could be bad considering the tonnes of force involved. I wouldn't want the ring to pulled over in one direction. Your original lacing distributes the forces very evenly over a much wider area -- seems to me a much better construction. However considering my lack of ropework talent and intuition, what do I know? Let's see how they work in practice.

[Dockhead]

P.S. -- another issue is the sharp bend of the strop around the padeye bail.

Mine are pretty beefy -- 8mm. But that's a 1:1 bend with 8mm dyneema, which is supposed to reduce strength by 50%. It also doesn't look good -- you can see how the fibers are crushed where they wrap around.

Don't quite know what to do about that without adding a lot of complexity (a thimble maybe, attached with some kind of metal shackle -- ick).

[Seaworthy Lass]

Originally Posted by Dockhead

P.S. -- another issue is the sharp bend of the strop around the padeye bail.

Mine are pretty beefy -- 8mm. But that's a 1:1 bend with 8mm dyneema, which is supposed to reduce strength by 50%. It also doesn't look good -- you can see how the fibers are crushed where they wrap around.

Don't quite know what to do about that without adding a lot of complexity (a thimble maybe, attached with some kind of metal shackle -- ick).

Just an off the cuff thought:
It is not ideal, as it adds complexity and length and the risk of bashing on the deck, but an easy solution is just to put another low tension ring on the other end (so you have a perfectly symmetrical strop). You still need to attach this to the pad eye, but an extra heavy duty soft shackle would work here (stronger than the strop, so it doesn't matter if it is being crushed). It makes the strop removable while there are lines running through it, which may be beneficial.

Edited to add: A very messy idea, but some elements may spark better thoughts.

SWL

[Dockhead]

Someone asked to see the strops in action. Here is my twing system:








As I write this, we are making 8.3 knots of boat speed in 10.5 knots of true wind -- hard on the wind.

This is far below the bottom of the wind range for which my blade jib was designed, but this magnificent sail has so little drag that there must be even much less wind than this, for there to be any advantage of the bigger 120% yankee, upwind.

We are heeling only 5 degrees and just cutting through the sparkling water of the Gulf of Finland.

One enormous advantage of this sheet lead system, which I never expected, is the profound effect of the inhauler, which changes angle of attack of the jib. It turns out that the jib reacts just as much, if not even more so, to small changes in angle of attack, as the mainsail does. Now I can't imagine not having this control.

[Seaworthy Lass]

Originally Posted by Dockhead

Someone asked to see the strops in action. Here is my twing system:

Attachment 127961

Attachment 127962

Attachment 127963


As I write this, we are making 8.3 knots of boat speed in 10.5 knots of true wind -- hard on the wind.

This is far below the bottom of the wind range for which my blade jib was designed, but this magnificent sail has so little drag that there must be even much less wind than this, for there to be any advantage of the bigger 120% yankee, upwind.

We are heeling only 5 degrees and just cutting through the sparkling water of the Gulf of Finland.

One enormous advantage of this sheet lead system, which I never expected, is the profound effect of the inhauler, which changes angle of attack of the jib. It turns out that the jib reacts just as much, if not even more so, to small changes in angle of attack, as the mainsail does. Now I can't imagine not having this control.

Dockhead, many thanks for the photos and the info xxx.

We still need to sit down and think about how the new boat will be rigged. I think we have enough attachment points everywhere to cover all bases, but we need more clutches and backing plates need to be added for these while they are welding. We will ask KM's advice on this, but it is good tho think about it ourselves first.

SWL