Comparing techniques used for eye splicing double braid polyester (=Class 1)

[Seaworthy Lass]

Originally Posted by Alan Mighty

Heather McLaren's work (see the link in the post above) deals with shorter lengths of tuck. And look at the splice techniques Bob Norson devised (also discussed above).


Shorter tucks do not seem so important. The nature of double braid, such that the strain on the cover compresses the core (and anything tucked inside the cover) and so shares the load. McLaren's and Norson's splices did not break at the splice. None of the splices pulled out.

For a diagram, see that done by Milne and McLaren (attached: canonical Class 1 double braid splice).

I haven't had the chance to read the article yet (your attached diagram distracted me ), but I bet the amount of core being cut off was not greater than the length of bury of the cover, which is what the Premium method is doing.

I have drawn on top of the diagram to illustrate what I was going on about in post # 8:

- The cover and core start out the same length.
- The length of cover is not changed.
- One tapered fid length of cover is buried past the loop of the eye
- More than one fid length of core is cut off in Premium's technique

This "works" in the Premium method as the the cover ends up bunched up differently, but milk it well (as Mark may be doing) or apply prolonged decent load and I bet it the relationship will want to equalize. Only locking stitches will "save" it then, but the ultimate strength of the splice will be weaker.

That is my gut feeling and why I don't like the Premium method.

I have marked over Milne and McLaren's diagram:

[Alan Mighty]

Originally Posted by Seaworthy Lass

That is my gut feeling and why I don't like the Premium method.

Point well made. I agree.


But:


1. Premium Ropes is a rope maker. I assume (with all the danger of making an ass out of you and me) that Premium has tested its splice.


2. In Heather McLaren's and Milne & A J McLaren's tests of double braid tests, only splices with very short tucks (1/5th of a fid, from memory) slipped. (see the Milne & A J McLaren paper in particular: they specify the lengths of the components of the bury)


3. Bob Norson is not a rope maker and so does not have a corporate responsibility with respect to his splices. Nevertheless, his 'Norson Double Splice' and 'Norson Splice' did not slip when tested. The splice that Norson reported was made by a UK splice pro also did not follow the Marlow/Samson canon.


4. I only do a few splices a year. I'm not casual about them at all. I follow the Marlow/Samson canonical technique (or rather, I follow Brion Toss's formula which I think has slightly longer buries of both core and cover).


Apart from that:


5. I remain amazed at the video of the Premium splice. When I do the final step, running the splice, I look more like Bob Norson (meaning: I wear leather gloves to do the milking, flex the splice, utter loud obscenities, resort to putting the splice under strain with a winch, and use a mallet and the floor to persuade the bury).


I can almost understand why the Samson video makes it look so easy: they choose a large diameter rope.


But Premium seems to be using a thin cordage (which I would expect to be tougher to complete). And still do it in minutes, without any hammering, flexing, flicking, gloves, etc.


So what's their secret (other than cutting corners, compared to Samson)?


Is my wearing of a wristwatch the problem (neither Samson nor Premium wears a watch)?

[Seaworthy Lass]

The diagram below illustrates further what may occur when more than one fid length of core is cut off when only one fid length of cover is buried, as in the Premium method.

The core tail in the Premium method still emerges where it should, but to achieve this when so much core has been cut off, somewhere along the way the core cover must bunch up.

I know the relationship will not be exactly 1:1 as stretching and bunching is necessarily occuring within the splice when the ends are buried, but cutting off more than one fid length just seems like a bad thing to do.
Looking at the YouTube, Samson only cut off about 2/3 of a fid length.

This may not seem like much in the scheme of things with a long line, but under load if the core and cover want to equalize to how they were originally, it is a big issue, as the core will no longer be held without the aid of lock stitches and this is not the intended purpose of these stitches.

SWL

I have marked over Milne and McLaren's diagram:

[Seaworthy Lass]

Originally Posted by Alan Mighty

Point well made. I agree.
But:
1. Premium Ropes is a rope maker. I assume (with all the danger of making an ass out of you and me) that Premium has tested its splice.

I will go out on a limb here (dangerous territory ) and say I very much doubt Premium tested the one in the YouTube.

Originally Posted by Alan Mighty

2. In Heather McLaren's and Milne & A J McLaren's tests of double braid tests, only splices with very short tucks (1/5th of a fid, from memory) slipped. (see the Milne & A J McLaren paper in particular: they specify the lengths of the components of the bury)

It is not the length of the bury I am objecting to, it is how much core was cut off while still achieving this bury in the Premium method.
The amount of bury of the core is positioned to be the same with both the Samson and Premium methods. The Premium method just achieves that in the YouTube by leaving the cover a bit looser.

Originally Posted by Alan Mighty

5. I remain amazed at the video of the Premium splice. When I do the final step, running the splice, I look more like Bob Norson (meaning: I wear leather gloves to do the milking, flex the splice, utter loud obscenities, resort to putting the splice under strain with a winch, and use a mallet and the floor to persuade the bury).

YES! Me too! That hit me like a mallet watching the YouTube.
For the Premium splice to be so easy to milk into position, the cover must be looser. The reason the cover is looser is that they are cutting off more core.
I commented on this in post #1:

Originally Posted by Seaworthy Lass

The different proportion of core to cover means that it would be a relatively easy splice to milk into seemingly completed position, possibly making it favourable for some people.

But what happens when prolonged load is applied without locking stitches?

Alan, splices do fail in practice.
I am acutely conscious of this, as I have been up the mast in a cat halfway between Sicily and Tunisia trying to fix things when two lots of halyard splices went in roughish conditions. I still bear the scars .

It would be good to know the best method of eye splicing the most common line still used cruising. My reaction looking at that Premium YouTube is that what has been shown is not the best practice.

SWL

[Alan Mighty]

Originally Posted by Seaworthy Lass

Alan, splices do fail in practice.
I am acutely conscious of this, as I have been up the mast in a cat halfway between Sicily and Tunisia trying to fix things when two lots of halyard splices went in roughish conditions. I still bear the scars .

Good point!


Heather McLaren (and Milne & A. J. McLaren, and Bob Norson) only tested steady strain to break.


Heather McL (who is now doing doctorate work in lubrication engineering) noted that cyclical forces can fail a splice. And reinforced that by saying that sailing is all about subjecting gear to cyclical forces, without stop.


No one tests for cycling forces.


Your point reminded me - I was chatting with a keen racer who keeps one of his boats on our dock finger. He advocated a Class II line for new halyards. I was arguing that I should go for a quality Class I line because of the continued doubt about the integrity of Dyneema subject to tight bends. His reply was: even if the Dyneema failed, what's the worst that could happen? Going aloft in tough conditions (or sending the Cook aloft in the same conditions) was my pathetic answer.


If it's going to break, it's most likely to follow Murphy's Law and do it at the least convenient time.

[Juho]

Nice discussion, thanks. I have made some splices but this discussion forced me to rethink what I have done.

I have some more observations that were maybe not fully covered yet.

1) In the Premium video the crossover point was made so that points 2 and T appeared to be right next to each other. (I use Samson names here. Point T was not named in the Premium video. See figure below.) Distance between T and R (A in Premium terminology) was about half fid. Distance between 1 (B') and 2 (C') was however one fid. This means that when the splice is stretched, the crossover points of the cover and the core will have different distance to the loop. This means that distance between T and 2 will grow. There will not be one crossover point but two separate ones (T, 2) as in the figure. Cover and core will run parallel between these points. In the Samson video these crossover points seemed to stay much closer (maybe intended to stay right next to each others).

2) In the Premium video distance from R (A) to the end of the cover was one fid. Distance from 1 (B') to 2 (C') was also one fid. This means that the cover may indeed back out and slip completely out from the core where it was put (when the distance between the two crossover points grows). This may not be as bad as it looks. It may be that the strength of the splice is not overly affected. Depending on the characteristics of the cover and core, the friction may be about the same also when the cover and core lie parallel within the outmost cover. One reason for putting the cover inside the core is to be able to milk the cover back in. From this point of view it is not a problem if the end of the cover at the end of the process slips out of the core.

3) Between points X and Z the diameter of the outmost cover is large since it may have two cores and one cover inside. This stretching means that the end of the cover will probably not reach as far as the end of the core. This explains to some extent why in both videos the end of the core seemed surprisingly long in the videos when it was cut shorter. Also in the Premium video the end of the core seemed to stay close to point Z although it was shortened quite a lot (length of the smaller fid).

4) When under stress a large part of the friction that keeps the loop in shape (i.e. the end of the cover and core do not slip out) comes from the loop itself. Inside the loop the core tries to move in opposite direction than the core, and because of the load there is a strong friction between the two layers. This friction may be even more important than the friction generated between X and Z. I don't really know, but this may explain why splices may work well even if the ends of the cover and core are not very long (as in the Premium video).

5) I note that in the Samson video the tapering of the core started already at point 4. If one wants to make the X-T section and all its components long to generate more friction, also Samson could do better (in the same way as Premium could). Practical tests would show how long the ends should be kept to get maximum friction without making the X-T section too long and bulky. Stitching that section could be useful in eliminating the risks of all king of random movements (maybe without load) that might make the splice fail in some specific circumstances.

I hope I got the logic and all the details in the text right.

Generic and easy to follow splicing instructions that would allow the user to pick whatever length of X-Z, R-T, T-2, 2-3 etc. would be nice. Some guidance would be needed on what is required for certain strength and reliability. Different characteristics of different ropes, changes in length when diameter grows, and class 2 ropes are some small challenges.

[s/v Jedi]

Premium Ropes is a Dutch company. This is their latest & greatest video on this splice. The text is in Dutch but easily comprehendible for the linguistically challenged :-)

They do tension the splice, then cut the excess tail at a point 4" away from the eye. I don't think the core can retract into the eye... anyway, here's their latest version:

https://www.youtube.com/watch?v=LkRV5gSn8LI

[Seaworthy Lass]

Originally Posted by s/v Jedi

Premium Ropes is a Dutch company. This is their latest & greatest video on this splice. The text is in Dutch but easily comprehendible for the linguistically challenged :-)

They do tension the splice, then cut the excess tail at a point 4" away from the eye. I don't think the core can retract into the eye... anyway, here's their latest version:

Hi Jedi
Many thanks for posting the updated video.

Edited to add: Scrap everything below. It is only in the second video that a smaller fid is used for measuring and the tail is actually cut off afterwards. It is Samson that cut it before.

Markwesti, sorry, but I have no idea where you are going wrong. It is a mystery.

As you point out, the biggest difference to Premium's first video is that the core tail is not cut off until after the splice has been milked into position.

Markwesti has been having problems with this method (the core does not end up in the loop at the end) and back in post # 15 I suggested he try precisely this:

Originally Posted by Seaworthy Lass

I think a very simple solution is not to cut any core tail off at all until you have finished the splice completely and put some decent, prolonged load on it.

My first thought as to why this problem was occuring for Mark was that C' had been marked incorrectly:

Originally Posted by Seaworthy Lass

I think it is likely the position you are marking C' is incorrect if you are finding this. This is the simplest error that would cause this problem.

I think this has now been confirmed and I will explain why:
It is now clear why Mark (and probably a score of other people) have had problems with the core being too short and why Premium have altered their video to avoid this.

In both their videos Premium are using a smaller fid (not the fid for this rope size) for their measurements:



If the fid correctly sized for the job is the larger one in the photo (Premium do use this for the cover, as the smaller one is too small) then the length is 21 x rope diameter. This makes the length of the smaller one they use 16 x diameter of the rope they are using.

This would primarily result in two things:

- The length of bury of the cover will be shorter. From Heather McLaren's work (link posted by Alan Mighty) decreasing this a bit this would not impact on the strength of the splice, so we don't need to worry about this.

Critically though:
- C (which is 1.75 fid lengths away from B' in both videos) would be 28 rope diameters away using the short fid, and 37 rope diameters if using the correctly sized fid for the rope, a whopping difference in length of 9 rope diameters.

I bet Mark was using a fid size that matched his rope size for the measurements. What was he thinking! This would put C 9 rope diameters too far from the end (if using 12 mm rope this would be 108 mm too far).
After feeding the core through the cover, 108mm extra would be cut off if this was done before milking, as the old video instructed, so the core would end up way too short and only halfway in the loop, as Mark found.

Mystery solved!

SWL

PS I have lots of comments about the new video, but I will answer Juho's interesting post first (hang on while I replenish my coffee ).

[s/v Jedi]

I was reading about the core and cover not being in balance when cut differently etc.... but as I understand it, the length of core that is cut away is equal to the length that the cover becomes shorter because it has to form around a bigger diameter contents.

There is another cool video from Premium about how they actually milk the cover back over the splice but I like to skip the drama and immediately use a shackle on the loop with a line to a winch. This makes it easy to do by yourself on a boat

here's that video... they do the winch trick smarter than I worked it out... will change that :-)

https://www.youtube.com/watch?v=luWu1OUd3XI

[Seaworthy Lass]

Originally Posted by s/v Jedi

I was reading about the core and cover not being in balance when cut differently etc.... but as I understand it, the length of core that is cut away is equal to the length that the cover becomes shorter because it has to form around a bigger diameter contents.

I agree that a bit of core needs to be cut off to allow for the changes in diameter. It is very complex to determine exactly what the correct amount should be, as all the portions of both core and cover in the splice area are either shortening or lengthening as they pass through each other (eg the cover passing through the core will end up longer than it would normally be).

Cutting off more than a fid length of core is a huge amount though. I cannot possibly see how the relationship can alter that much.

Simply having the fid length of cover buried too far from the end of the core will result in this.
Starting it that far away makes milking easier, but it will make the splice weaker.

SWL

[s/v Jedi]

Originally Posted by Seaworthy Lass

Yes, I agree that a bit of core needs to be cut off to allow for the changes in diameter. It is very complex to determine exactly what the correct amount should be, as all the portions of both core and cover in the splice area are either shortening or lengthening as they pass through each other (eg the cover passing through the core will end up longer than it would normally be).

Cutting off more than a fid length of core is a huge amount though. I cannot possibly see how the relationship can alter that much.

Simply having the fid length of cover buried too far from the end of the core will result in this.
Starting it that far away makes milking easier, but it will make the splice weaker.

SWL

well... the proof is right there staring us in the face: both cover and core are nice and tight, it is tensioned, the core exits 4" beyond the splice and excess there is cut off. There is no slack in the buried cover that will creep later or any other reason for the core to retreat back into the loop...

Remember that every rope is different and the part that needs to be cut will be different as a result. Not just diameter but also how tight the cover and core are woven. I'm ordering some XLS Yachtbraid instead of the usual StaSet because I think it splices better (and is cheaper ) I always tension, check that everything is tight and straight and then cut the core to length. I still like Amsteel Blue much better

[Alan Mighty]

Originally Posted by s/v Jedi

here's that video... they do the winch trick smarter than I worked it out... will change that :-)

The use of the hammer, the need to put a steady strain and snatch forces on the rope ... all look more like real life.

[Seaworthy Lass]

Jedi, this illustrates what I consider is a problem:

I fid "length of cover" is being buried.
More than on "fid length" of core is being cut off at the end:

I have marked over Milne and McLaren's diagram:

[Seaworthy Lass]

I think Premium need to take a few tips from Samson

From Premium's video it is clear the main reason they are struggling so much is that they have allowed bunching of core to occur at the base of the eye.

In both their video (see post #1 for the link), as well as in their pdf, Samson describe how to both help avoid and deal with bunching:

http://www.samsonrope.com/Documents/...Splice_WEB.pdf

Jedi, watch Premium's video again. At the very end of the video when they actually only moderately firmly milk the cover all the way from the tied point, excess cover appears super easily. That relationship is not tight.
Even though they have cut so much core off, they are struggling so much because they have allowed bunching up of the core to occur.

Yes, the cover is very tight over the base of the loop, but the relationship between length of core and length of cover for the zones above and below this junction is likely to be incorrect in my opinion.

Jedi, Dutch honour is not at stake here. We are just trying to determine the best way of splicing. For whatever reason, eye splices do fail in practice.

SWL

[Seaworthy Lass]

These two stills from Premium's video show how they allow bunching to occur at the base of the loop.

They are struggling so much because of this bunching, not because there is a correct relationship between the length of the core and cover above and below the tight section where the cover is buried.

I have circled the bunching: