Stealth mode - New Generation Ropes

[fxykty]

Originally Posted by real_goat

I have just received the YSM Aero ropes I ordered.

Ordered on the 15th, they probably received my payment on the 17th and immediately send them out.
Can highly recommend them!

Great site (and with my Polish heritage I like their location too). I’ve ordered directly from Greenline Fishing in Denmark and their prices for Acera Amundsen are comparable. Less than half, even with shipping, of the least expensive quote I got in NZ! The key for any UHMWPE single braid is the UV and abrasion coating and how it is applied to the rope.

[Breaking Waves]

Originally Posted by fxykty

The key for any UHMWPE single braid is the UV and abrasion coating and how it is applied to the rope.

I hope you also realize there are quite different grades of UHMWPE. Was just looking at some inexpensive stuff and noticed it was SK60.

dyneema.jpg Views: 100 Size: 131.7 KB ID: 192484" style="margin: 2px" />

[Juho]

Originally Posted by StuM

You had me confused at first because your knot is tied "opposite handed" with a twist in the ears and shown from the opposite side to Ashley's illustation fo ABOK#1097. But you are correct, that is what it is, eventually.

It seems ABOK #1097 can be seen and tied in many ways. I tried several ways of tying it. I'll present the simplest and most practical method that I found.

Throw the loop over your finger (image 1). Form one smaller loop by lifting part of the hanging loop over your finger to the opposite side (image 2). Hold the crossing point in place with your thumb. Do the same thing to the other side of the hanging loop, except that now the new smaller loop dives under the two lines that ran over your finger in the first image (image 3). Adjust the length of the loops and tighten the knot (by pulling from all the six lines one by one).

As for the knot itself, Ashley's comments are pertinent:

"As this knot is easily remembered and is exceedingly secure, it would probaby be the most pratical of all SPLAYED LOOPS were it not for the fact that it is harder to untie that some others."

Yes, Ashley's comments are quite pertinent. There are knots that are easier to untie, but I would say that untying this knot, after tightening it with about as much strength as I have in my hands, was still quite easy. The best technique seems to be to bend each one of the three small visible rope segments (see image 4) over, so that the knot looks as in image 5.

[fxykty]

I’m getting all confused again and have lost track of the WSMurdoch solution. Assuming large eye on each leg of the bridle and large eye on the leader, the four soft options for connecting bridle legs to leader in UHMWPE are:
1) All eyes spliced interlocking with each other. If one of the bridle legs is unloaded it can move, which can mean rapid movement on taking up load. Relatively high chafe and temperature issues.
2) Leader eye girth hitches around the two bridle eyes. Undressed minimises bends in the hitch. Least movement, but possible strength loss due to relatively sharp bends at the hitch, especially if large change in direction between the leader and one or both bridle legs. Preferred solution?
3) All eyes spliced into a loop. As for 1), there can be rapid movement and also continuous movement of all three eyes. The hard equivalent would be a ring and possibly girth hitching to it.
4) Bridle eyes spliced into a one part of a doubled loop and leader eye spliced into both parts of the doubled loop. As for 3) there can be continuous movement, but we can consider the loop as disposable and give it a good high temp chafe cover. All splices would have to be redone, which is a bit of a pain. Could girth hitch each eye to the loop to avoid resplicing and movement, but gain a bit of structural stress.

Any thoughts?

[Dockhead]

Originally Posted by Breaking Waves

I hope you also realize there are quite different grades of UHMWPE. Was just looking at some inexpensive stuff and noticed it was SK60.

Attachment 192484

The "YSM Aero" ropes above are quoting 102kN breaking force for 10mm, which is somewhat better than SK78 Dyneema. Interesting.

[Dockhead]

Originally Posted by fxykty

I’m getting all confused again and have lost track of the WSMurdoch solution. Assuming large eye on each leg of the bridle and large eye on the leader, the four soft options for connecting bridle legs to leader in UHMWPE are:
1) All eyes spliced interlocking with each other. If one of the bridle legs is unloaded it can move, which can mean rapid movement on taking up load. Relatively high chafe and temperature issues.
2) Leader eye girth hitches around the two bridle eyes. Undressed minimises bends in the hitch. Least movement, but possible strength loss due to relatively sharp bends at the hitch, especially if large change in direction between the leader and one or both bridle legs. Preferred solution?
3) All eyes spliced into a loop. As for 1), there can be rapid movement and also continuous movement of all three eyes. The hard equivalent would be a ring and possibly girth hitching to it.
4) Bridle eyes spliced into a one part of a doubled loop and leader eye spliced into both parts of the doubled loop. As for 3) there can be continuous movement, but we can consider the loop as disposable and give it a good high temp chafe cover. All splices would have to be redone, which is a bit of a pain. Could girth hitch each eye to the loop to avoid resplicing and movement, but gain a bit of structural stress.

Any thoughts?

Some thoughts:


I don't think the disadvantages of Option 1 are correctly described. Temperature? What temperature issues? Chafe? I don't think we get any chafe at all in completely unloaded rope elements as slippery as Dyneema -- you need some load to produce chafe. Any load at all on a bridle will fix that eye loop into the apex of the leader eye loop, and if both bridle leg eye loops have any load at all, even if there is a large difference between those loads, they will both be fixed together right in the apex. Snatch load as a completely unloaded bridle leg eye loop is suddenly loaded, is the only issue I can think of for this variant, and I don't know if this is worse than snapping the slack out of a piece of rope simply. I doubt that this is any problem, but I would be glad to be corrected if this is not so. Another possible issue which I don't understand is fibers scrunching around two pieces of rope with a half twist. I have no idea whether that reduces strength or over the long term damages the rope.




Option 2 has the same scrunched fiber issue, which I can't evaluate, and more severe. Eliminates motion of unloaded bridle leg eye loops, but I'm not seeing why this is any advantage.



Option 3 -- there will be movement of eye loops on the gasket under load, so possibility of chafe. I don't like this. I think this could be an ideal solution without any fiber scrunching or any other unevaluatable issues, but only if using a suitable polished metal ring rather than a gasket. I think this is my preferred version provided a suitably rated proof tested forged ring could be sourced.


Option 4 -- chafe. No like. You can say that the gasket is disposable, but how long will it last? Why have any intentionally wearing out element at all in the system, if it's not necessary? If I'm trying to get around the Five Capes and have to deploy the drogue multiple times for extended periods, do I really need, on top of everything else, to be worrying about whether the bloody gasket in my drogue still has enough life left in it? Note that not only the gasket, but the bridle and leader eye loops will wear out. No like.




My opinion might change in favor of 1 or 2 if I better understand the fiber scrunching question, but so far I like 3 with a metal ring.

[Seaworthy Lass]

Originally Posted by Dockhead

The "YSM Aero" ropes above are quoting 102kN breaking force for 10mm, which is somewhat better than SK78 Dyneema. Interesting.

On their website this rope is marketed as Dyneema with a registered trademark, but interestingly on the certificate provided Dyneema is not mentioned.

Even more interestingly, the figure of 102kN corresponds exactly to Acera Amundsen.

I wonder if this is Acera? If so, it is comparable to the price from the fishing chandlery in the Netherlands.

SWL

[Dockhead]

Note that parachutists trust their lives to forged rings all the time:


Rings (O-Rings, D-Rings &amp V-Rings) - Cirrus Parachute Hardware Equipment


I would bet that a suitable piece could be found.

[Seaworthy Lass]

Originally Posted by fxykty

I’m getting all confused again and have lost track of the WSMurdoch solution. Assuming large eye on each leg of the bridle and large eye on the leader, the four soft options for connecting bridle legs to leader in UHMWPE are:

1) All eyes spliced interlocking with each other. If one of the bridle legs is unloaded it can move, which can mean rapid movement on taking up load. Relatively high chafe and temperature issues.

Yes, this is the solution that Dockhead and Jedi suggested. The chafe issues having one leg that is loose when under load may be minor as Dockhead suggests, but are unknown. Generally, as far as I am aware, these drogues have never been constructed with loose elements at junctions, so we have little to go on.

The apex of one bridle is sometimes compressed on both sidesby the full load using this technique. Effect of this is unknown, particularly with prolonged load, as in this application.
If chafe with movement of a loose leg is not considered an issue, then why not incorporate a soft loop and eliminate this particular issue?

In addition, shock loads on the apex of one leg of the bridle rather than the main body of the bridle may be a problem (my gut feeling is they are). Again, effect is unknown.


2) Leader eye girth hitches around the two bridle eyes. Undressed minimises bends in the hitch. Least movement, but possible strength loss due to relatively sharp bends at the hitch, especially if large change in direction between the leader and one or both bridle legs. Preferred solution?

Yes, this is what WS Murdoch proposed. Bends are much less severe than in any other knotted option presented so far.

Note that if you treat the bridle eyes as one unit, they can also be hitched onto the leader. This saves a long length of line having to be passed through the bridle eyes, particularly if anyone is redoing this junction.


3) All eyes spliced into a loop. As for 1), there can be rapid movement and also continuous movement of all three eyes. The hard equivalent would be a ring and possibly girth hitching to it.

I would consider 3) as the eyes spliced simply onto the leader. It had the same issues as 1), except for the compression on the top of the apex of one of the bridle eyes is not present.

All three of the above options (and also option 5) can have a loop incorporated at the junction and for options 1, 3 and 5 it can be a hard loop.


4) Bridle eyes spliced into a one part of a doubled loop and leader eye spliced into both parts of the doubled loop. As for 3) there can be continuous movement, but we can consider the loop as disposable and give it a good high temp chafe cover. All splices would have to be redone, which is a bit of a pain. Could girth hitch each eye to the loop to avoid resplicing and movement, but gain a bit of structural stress.

I haven’t seen this option discussed. What would stop the double loop shifting in proportion when load is just on one leg?

I would add:

5) Current system of bridle legs cow hitched to the leader, but make sure the leader eye is extra long so the throat angle is very shallow to minimise tearing forces at the throat. When made up in slippery UHMWPE, each cow hitch may shift to the central position when load is only on one leg. With rough double braid poly this may not be occcuring currently.

We have a lot of options to consider, all with their pros and cons.
Personally, I am going with 2) with a single loop added at the junction with no additional chafe protection here.

SWL

......

[Dockhead]

Originally Posted by Seaworthy Lass

On their website this rope is marketed as Dyneema with a registered trademark, but interestingly on the certificate provided Dyneema is not mentioned.

Even more interestingly, the figure of 102kN corresponds exactly to Acera Amundsen.

I wonder if this is Acera? If so, it is comparable to the price from the fishing chandlery in the Netherlands.

SWL

It looks like Acera -- same color, too. I guess we could ask them.


For the record, Acera has an excellent coating and handles very well. Dyneema is sold with all kinds of different coatings, some of them quite inferior for the kind of uses we have. I've binned a bunch of Dyneema strops and loops which frizzed out.

[Dockhead]

Originally Posted by Seaworthy Lass

..5) Current system of bridle legs cow hitched to the leader, but make sure the leader eye is extra long so the throat angle is very shallow to minimise tearing forces at the throat. ....

This is how my drogue is currently made, and the leader eye loop is quite long.



It's been said before, but N.B. that lengthening the leader eye loop will NOT reduce the throat angle below the natural angle of the bridle legs to each other (23 degrees IIRC). If the leader eye loop is too short, it may increase this angle (because of the bulk of the cow hitches keeping the bridle eye loops apart) and thus the throat-tearing force, but can't be reduced.

[Seaworthy Lass]

Originally Posted by Dockhead

It's been said before, but N.B. that lengthening the leader eye loop will NOT reduce the throat angle below the natural angle of the bridle legs to each other (23 degrees IIRC). If the leader eye loop is too short, it may increase this angle (because of the bulk of the cow hitches keeping the bridle eye loops apart) and thus the throat-tearing force, but can't be reduced.

Dockhead, I think you are wrong here.
Mock it up with some bits of twine and it is apparent this is not the case.

The angle can be reduced beyond the natural angle of the bridle legs. Thus the tearing force can be reduced by making the eye longer. It is a mistake I made earlier.

SWL

[Dockhead]

Originally Posted by Seaworthy Lass

Dockhead, I think you are wrong here. It is a mistake I made earlier.
Mock it up with some bits of twine and it is apparent this is not the case.

SWL

Well, I should say that if the eye loop is so long that the geometry of the bridle is changed, then yes, the angle can be reduced.


But if the leader eye loop is long enough not to be holding the bridle legs apart in one way or another, and provided there is no interconnection between the two bridle leg eye loops or any other force holding them together, then there will be a straight line from each chain plate all the way to the throat of the leader eye loop, with a 23 degree angle, provided the distance from chain plate to throat is 2.5x the distance between the chainplates, as per the JSD spec.


How could it be otherwise? The straight lines between chainplates and throat can be tweaked only by some force; lengthening the eye loop won't do that by itself.


This also assumes that the cow hitches are free to move out along the leader eye loop until the forces are in equilibrium. If you had a really long loop and the cow hitches were cinched down really tight before any force was applied, maybe friction would hold the cow hitches together for some time, but once you have a load of several tonnes on the system, I wouldn't think this force would hold the cow hitches on the slippery HMWPE loop for long. The load on the system will be trying to force the legs apart until there is a straight line between chain plate and leader eye throat.

[Seaworthy Lass]

Originally Posted by Dockhead

Well, I should say that if the eye loop is so long that the geometry of the bridle is changed, then yes, the angle can be reduced.


But if the leader eye loop is long enough not to be holding the bridle legs apart in one way or another, and provided there is no interconnection between the two bridle leg eye loops or any other force holding them together, then there will be a straight line from each chain plate all the way to the throat of the leader eye loop, with a 23 degree angle, provided the distance from chain plate to throat is 2.5x the distance between the chainplates, as per the JSD spec.


How could it be otherwise? The straight lines between chainplates and throat can be tweaked only by some force; lengthening the eye loop won't do that by itself.


This also assumes that the cow hitches are free to move out along the leader eye loop until the forces are in equilibrium. If you had a really long loop and the cow hitches were cinched down really tight before any force was applied, maybe friction would hold the cow hitches together for some time, but once you have a load of several tonnes on the system, I wouldn't think this force would hold the cow hitches on the slippery HMWPE loop for long. The load on the system will be trying to force the legs apart until there is a straight line between chain plate and leader eye throat.

Dockhead, just mock it up
I made exactly the same incorrect assumption.

SWL

[fxykty]

Originally Posted by Seaworthy Lass

......

Option 2 with a single loop. Please explain how/where you are incorporating a loop. Thanks.