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

[Seaworthy Lass]

Jedi, please don't get upset that I am criticizing a Dutch manufacturer's splicing method .

We are having a Dutch boat built simply because we think they are master craftsmen in this area, so I have a huge admiration for the Dutch.

I have a few observations to make about Premium's revised video that you posted a link to:

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

What I don't like about this revised method:

- No distant knot is tied to limit which portion of the line the core is being pulled from.

- The tail of the cover is tapered poorly and the tail of the core not tapered at all. I don't know how much this will weaken splices in double braid, but it certainly does in single braid. Samson take time and care to taper very evenly.

- Horrifically, Premium pull out the core out by snagging strands. This will reduce the strength of the core. Some of the fibres look fuffy indicating they have been pulled out or even torn.
Heather McLaren touched on the risks of this in her paper on the strength of eye splices (see Alan Mighty's link):
"Removing the core from the sheath carried a high risk of pulling strands of fibres – in a tensile test, the shortest fibres bear the load until they break and the load is redistributed to the next shortest fibres, and so it is preferable to have all fibres at an even length."

- Premium spike buried cover crossways with a fid to hold it instead of taping. More fibre damage to the core is possible when doing this. To avoid the risk of damage, a carefully inserted awl would have been preferable, and tape would have been better still.

- More than a fid length of core is still being cut off at the end. This is my biggest concern.

I welcome any comments.

SWL

[Seaworthy Lass]

Originally Posted by 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.

Hi Juho
Thanks for adding to the discussion and all the observations. I will comment on some of the points later. You have made lots of good ones (I think they are good because I agree with them ).

Firstly, I agree wholeheartedly that it would be nice if there were standard names for the marks made .
When some manufacturers use A, B and others R, X it makes it difficult to compare what they are doing!
Also some methods specify marking the end of the bury of the cover in the core (Premium with D), others the beginning (Samson with mark 2).

I also think it would help tremendously if units of measurement were referred to as "rope diameter" not "fid length". People are using all sorts of fids for this work: Swedish (Selma type), splicing needles, splicing wands and home made equipment.
Some manufacturers like Premium are not even using fids matched to the rope size for their measurements and don't tell you what they are using .

It is an excellent idea marking the estimated position of the rest of the marks on a cross section of an eye splice to help clarify what is happening.
I have marked a few alterations though on your diagram using Samson's method :

SWL

[Seaworthy Lass]

Originally Posted by Juho

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.

Yes! That is my view as well. Initially only half the cover is buried in the core. With movement of the core (and I think it is very likely to move under heavy, prolonged or cyclical load, as so much has been cut off to make it "fit"), the distance between Premium's equivalent T and 2 points will grow. I would hazard a guess that there may eventually not be much cover inside core.

This is what I was trying to say back in post #13:

Originally Posted by Seaworthy Lass

I predict for the Premium method when load is applied without the stitches the core is going to slide down closer to where it originally started and even less of the cover will end up buried in the core. This will not be at all visible or felt. The cover will still remain buried in the cover for a full fid length (unless the splice fails).

I can't comment though how much of a "problem" this is. I tend to think that the core will be helping to grip the cover and helping it to stop pulling out, so it is not a good thing to have the tail of the cover gripped only by the cover, but I don't know.
If the cover is looser further down (and it must be in the Premium method, as they cut off excess core), then when load is applied the grip of the cover will not be as good.
On the other hand, the grip by the core will be high, as it is taking the load, so a longer length grip by the core sounds like it would be super good.

Originally Posted by Juho

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).

Yes, the end of the cover definitely does not reach the end of the core. The two ends are at least 2/3 of a fid length apart. Samson instruct the end of the core (Z) to be 1/3 of a fid length from X. Premium just vaguely write 5-10 cm irrespective of line diameter . This is why Samson cut off 2/3 of a fid length at the end (the cover is buried a fid length from R/X and the core less than a third of a fid length from R/X). That geometry makes sense to me and I am OK with that, although I would like to see XZ longer. I guess having a long section of bury of cover and two cores means you need to be superman to milk the splice, so it has been shortened to the current amount.
It would be interesting to see failure mode.

What I am not happy with is that Premium cut off more than a fid when only a fid of the cover was buried initially.

Originally Posted by Juho

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).

That sounds logical to me. There is probably roughly a fid length of bury in the loop for about a thimble sized loop, so the grip there must be playing an important part.

Originally Posted by Juho

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 think the key is that friction (grip) is needed rather than strength in the tapered area (the line is doubled here, so only half the strength is needed) and having the cover tail and core tail suddenly go from from thick to thin is much worse than a gradual taper.
Just my hypothesis .

Juho, thanks again for thinking all this through so carefully. It is very helpful and it is nice being able to toss ideas around.

SWL

[s/v Jedi]

SWL please don't make this is Dutch pride thing... I have emigrated from Holland long ago, have never bought any rope from these guys, never did their splice and probably never will. The only reason I bring up the Dutch versions from their videos is because they state that this is their new, improved version. Something non-Dutch speaking people can't read as the text explaining it is in Dutch.

Again, the amount of excess core is directly related to the shrinking of the cover as it needs to hold a bigger diameter contents. As Samson does so much tapering (a good thing IMHO), their cover shrinks less and so they have less excess core.

You want to see number of core diameters used instead of number of fids. There is a direct relationship between the two. The old school fids have a mark for a "short fid" but the Selma fids have this marked as where the cut open back closes to full tubular. All traditional splicing instructions use fid lengths incl. Samson. Brion Toss explains it all in-depth in his Riggers Apprentice. IIRC, which is so-so, the fid equals 21 rope diameters. When several sizes fids are used, it is often one for the rope diameter and one for the core diameter. Sometimes they specify to use a "small fid" which is a size under regular.

The rope that you think is bunched upn the splice, is okay. This is just the friction of getting it to bury in the cover. As soon as it slips in, the tension on the rope will smooth it back perfectly. When you don't use a winch, you need to put a handle through the eye of the splice and yank it a couple times to achieve the same.

What I recommend you to do, is to perform each version of the splice, then test between two winches to see if one slips, then cut each one open to verify and document differences. I can tell you now that when part of the eye ends up without core, or if the buried cover has come out of the core, with either method, then an error has been made during the splice.

For double braid I normally do the Samson splice. Or the Selma splice, sometimes the New England splice or the Brion Toss splice. They are all the same and I think strength will be within 5-10% of each other, with a well tapered splice at the high end, which is why I take the time for that tapering.

p.s. Did you see the Sailrite splice videos? :-)

[Alan Mighty]

Here is my first attempt to compare two versions of what I call the canonical Class 1 double braid eye splice. Those two versions are from (1) Samson Ropes; and (2) Brion Toss.

I started wanting to include the techniques recommended by Marlow, Premium Ropes, and Selma Fids (the latter because it seems endorsed by Touwfabriek Langman - but I've not found an explicit recommendation from Langman on its splicing preference).


Grappling with the detail, I decided that Marlow's splice and Premium takes shortcuts that give me a headache. The Selma Fid version is less well detailed than that of Samson Ropes. I may come back to these three later.


I wanted to include Marlow's splice, because Milne & A J McLaren's paper used that technique for its splice testing. Andrew J McLaren is a lecturer at Strathclyde U and was the supervisor of Heather McLaren and other mech engineering students who followed his lead into testing knots and splices for their projects.


I gave a URL for the Milne & A J McLaren paper earlier in this thread. If you want to see it, other of his students' projects (including that of Heather McL), and a few other links, see: Dr. Andrew McLaren's Project Page


The Milne & A J McLaren paper looked at a couple of knots, a splice in laid rope, and a double braid splice. With respect to the double braid splice, they varied the length of the eye loop, the size of the line, and the length of the splice (more or less the equivalent of the RZ or XZ dimension) as well as varying the lengths of the bury of core and cover.


Milne & A J McLaren conclusions included:


1. an optimum length of splice (RZ) exists, such that below that length the splice slips and above that length the splice or rope breaks.


2. eye loop size has no effect.


3. splice efficiency reached a max at rope diameter = 8 mm, but bigger rope is still stronger.


My next step with regard to the Samson Ropes and Brion Toss versions of the double braid splice will be to try to work out the resultant bury dimensions, splice length, etc. And to see what lessons are in Milne & A J McLaren to apply to that.


Another step will be to pick up Juho's suggestion and SWL's suggestion about what small changes to the marking might theoretically make an even better splice (if that is possible).


Enough for now.


Here's my first stab at a comparison table. Comments and corrections welcome, of course.

[Seaworthy Lass]

Originally Posted by s/v Jedi

SWL please don't make this is Dutch pride thing..

Originally Posted by s/v Jedi

Again, the amount of excess core is directly related to the shrinking of the cover as it needs to hold a bigger diameter contents. As Samson does so much tapering (a good thing IMHO), their cover shrinks less and so they have less excess core.

Jedi, the relationship is actually very compex because the BOTH the core and cover will lengthen and shrink as they bury and are being buried within the splice (it is not just the outside cover than changes in length), but I think that no matter how the cover and core shrink and expand, there is no way more than a fid length of core can be cut off when there is only a fid length of cover buried in the first place, and yet still maintain a good relationship between core and cover.

Originally Posted by s/v Jedi

You want to see number of core diameters used instead of number of fids. There is a direct relationship between the two. The old school fids have a mark for a "short fid" but the Selma fids have this marked as where the cut open back closes to full tubular. All traditional splicing instructions use fid lengths incl. Samson. Brion Toss explains it all in-depth in his Riggers Apprentice. IIRC, which is so-so, the fid equals 21 rope diameters. When several sizes fids are used, it is often one for the rope diameter and one for the core diameter. Sometimes they specify to use a "small fid" which is a size under regular.

Yes, I know a fid length is 21 x rope diameter (see post #17), but not everyone else watching the videos does. This unit is of no use to someone using homemade fids when they haven't researched what the conversion is relative to the rope size they are using.
It doesn't help either that Premium use a smaller fid as reference point for their measurements, not a normal one. They don't even tell us what they are using. Some standardization here (and rope diameter is the best reference point I think) would be extremely useful.

Originally Posted by s/v Jedi

What I recommend you to do, is to perform each version of the splice, then test between two winches to see if one slips, then cut each one open to verify and document differences. I can tell you now that when part of the eye ends up without core, or if the buried cover has come out of the core, with either method, then an error has been made during the splice.

This is actually an excellent suggestion. When I have access to a winch again, I will do this .

Originally Posted by s/v Jedi

For double braid I normally do the Samson splice.

A man after my own heart .
I am impressed by their method. I think they have had some advice from someone with good understanding of rope. I wonder if Evans had any consulting input in this?

Originally Posted by s/v Jedi

p.s. Did you see the Sailrite splice videos? :-)

No, do I need to have a shot of alcohol first?

SWL

[s/v Jedi]

I recommend the Sailrite videos. They seem rather silly but add new details and actually become funny when the firm tugging results in some studio damage

What I like from them is they show you another method of dealing with cover-slack in the eye-part, a nice method of lock-stitching the finished splice and in general add to total knowledge. I always watch a Sailrite video.

There's another good one from an arborist service who does the Samson splice.

https://www.youtube.com/watch?v=7B_dW_-e7IM

[UNCIVILIZED]

Originally Posted by Alan Mighty

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.

Funny thing, many folks ask me why I advocate tying the halyard to one's climbing harness, rather than just using the shackle on the splice. And upon hearing my explanation (akin to the above), promptly blow it off. Not that the possibility of a splice failure or shackle opening is the only reason for tying in, but...

[Alan Mighty]

Baby steps forward in comparing the techniques of Samson Ropes and Brion Toss. Steps added include tapering and stitching.

I've dealt with the increased size of the table by attaching it as an Excel file (too big for a graphic)

[Seaworthy Lass]

Originally Posted by Alan Mighty

Baby steps forward in comparing the techniques of Samson Ropes and Brion Toss. Steps added include tapering and stitching.

I've dealt with the increased size of the table by attaching it as an Excel file (too big for a graphic)

Alan, that is fantastic!
So easy to see at a glance what is going on and to compare methods.

I haven't had a chance to analyse what Brion Toss is doing (not enough hours in the day ), but I have had a quick look at what you have listed for Sampson and it all looks correct, except you just need to move the tapering over by one column (see below).

Interestingly, the biggest difference between the Samson and Toss methods is the distance XZ (double in Toss's). That was my only thing I commented that I thought could be improved with the Samson method:

Originally Posted by Seaworthy Lass

......That geometry makes sense to me and I am OK with that, although I would like to see XZ longer. I guess having a long section of bury of cover and two cores means you need to be superman to milk the splice, so it has been shortened to the current amount.

I like that Brion has lengthened the amount of bury of core tail .

SWL

[Seaworthy Lass]

Originally Posted by Alan Mighty

Here is my first attempt to compare two versions of what I call the canonical Class 1 double braid eye splice. Those two versions are from (1) Samson Ropes; and (2) Brion Toss.

I started wanting to include the techniques recommended by Marlow, Premium Ropes, and Selma Fids (the latter because it seems endorsed by Touwfabriek Langman - but I've not found an explicit recommendation from Langman on its splicing preference).

Grappling with the detail, I decided that Marlow's splice and Premium takes shortcuts that give me a headache. The Selma Fid version is less well detailed than that of Samson Ropes. I may come back to these three later.

I wanted to include Marlow's splice, because Milne & A J McLaren's paper used that technique for its splice testing. Andrew J McLaren is a lecturer at Strathclyde U and was the supervisor of Heather McLaren and other mech engineering students who followed his lead into testing knots and splices for their projects.

I gave a URL for the Milne & A J McLaren paper earlier in this thread. If you want to see it, other of his students' projects (including that of Heather McL), and a few other links, see: Dr. Andrew McLaren's Project Page

The Milne & A J McLaren paper looked at a couple of knots, a splice in laid rope, and a double braid splice. With respect to the double braid splice, they varied the length of the eye loop, the size of the line, and the length of the splice (more or less the equivalent of the RZ or XZ dimension) as well as varying the lengths of the bury of core and cover.

Milne & A J McLaren conclusions included:

1. an optimum length of splice (RZ) exists, such that below that length the splice slips and above that length the splice or rope breaks.

2. eye loop size has no effect.

3. splice efficiency reached a max at rope diameter = 8 mm, but bigger rope is still stronger.

My next step with regard to the Samson Ropes and Brion Toss versions of the double braid splice will be to try to work out the resultant bury dimensions, splice length, etc. And to see what lessons are in Milne & A J McLaren to apply to that.

Another step will be to pick up Juho's suggestion and SWL's suggestion about what small changes to the marking might theoretically make an even better splice (if that is possible).

Alan, I'll look at Marlow's method and help, or at least check what you come up with.
I agree that trying to quantify Premium is headache inducing. They do not specify the position of T , which makes comparisons difficult in a table. I will see what I can do to estimate this from their video so we have another method to add to your spreadsheet.

My only suggestions for improvement in the methods Samson & Toss use are these two (just based on gut reaction rather than any testing):

1. Make XZ longer than Samson does (Brion Toss makes it longer).
McLaren's work did show that what Samson use is perfectly OK when applying constant load. Other things affect the splice though - cyclical load etc, that may mean a longer bury of the core is needed than the data indicates.

2. Make distance I-II a bit shorter.
I guess this distance would have been determined by what is found to be needed in practice after milking. The care taken will influence this, as will the brand of line used probably (relationship between core and cover will probably alter between manufacturers). It is kind of a "fudge factor" that has been incorporated to allow for all the expansion and contraction that is going on within the splice.
If greater care/effort/time is taken with milking it may be possible to reduce this distance. I will try this as soon as I get hold of some more new line.

SWL

[Alan Mighty]

Originally Posted by Seaworthy Lass

you just need to move the tapering over by one column.

Well caught. I had my head in the spreadsheet cells and was not looking up from the chart table to keep aware of the whole situation.


I've also moved a couple of stitching cells.


See new baby steps.xls.

Originally Posted by Seaworthy Lass

Interestingly, the biggest difference between the Samson and Toss methods is the distance XZ (double in Toss's). That was my only thing I commented that I thought could be improved with the Samson method

Yes. And it was your and Juho's valuable comments that prompted me to do the job of starting a comparison spreadsheet.


Milne & A J McLaren and Heather McLaren's research work all point to the dimensions of tucked bits and the dimension of core disturbance being critical.


The next non-baby step is to try to work out those dimensions. Some of it may need to be done as a post-mortem by dissecting a made splice, as noted by Jedi.

[Alan Mighty]

Originally Posted by Seaworthy Lass

Alan, I'll look at Marlow's method and help, or at least check what you come up with.

My reading of Marlow was that they do a different splice. I welcome your excellent attention to detail and capacity to cope better than I do with the structures involved. I'm slow and have to draw it out and play with cordage.

Originally Posted by Seaworthy Lass

My only suggestions for improvement in the methods Samson & Toss use are these two (just based on gut reaction rather than any testing):

1. Make XZ longer than Samson does (Brion Toss makes it longer).
McLaren's work did show that what Samson use is perfectly OK when applying constant load. Other things affect the splice though - cyclical load etc, that may mean a longer bury of the core is needed than the data indicates.

2. Make distance I-II a bit shorter.
I guess this distance would have been determined by what is found to be needed in practice after milking. The care taken will influence this, as will the brand of line used probably (relationship between core and cover will probably alter between manufacturers). It is kind of a "fudge factor" that has been incorporated to allow for all the expansion and contraction that is going on within the splice.
If greater care/effort/time is taken with milking it may be possible to reduce this distance. I will try this as soon as I get hold of some more new line.

I agree wholeheartedly.


1. The XZ dimension looks critical to resisting both a steady strain and, I hope, cyclical stress.


2. One of the McLarens (I think Heather) alerted us to this. Too long a I-II and the disturbance is greater.


I figure that one way to proceed further, other than to come up with a better version for CF, is to talk to Andrew McLaren (and suggest that he and one of his students do some testing), Brion Toss, and Samson Ropes.

[Seaworthy Lass]

Originally Posted by Alan Mighty

Well caught. I had my head in the spreadsheet cells and was not looking up from the chart table to keep aware of the whole situation.

I've also moved a couple of stitching cells.

See new baby steps.xls.

Yes. And it was your and Juho's valuable comments that prompted me to do the job of starting a comparison spreadsheet.

Milne & A J McLaren and Heather McLaren's research work all point to the dimensions of tucked bits and the dimension of core disturbance being critical.

The next non-baby step is to try to work out those dimensions. Some of it may need to be done as a post-mortem by dissecting a made splice, as noted by Jedi.

I have been thinking about post mortem work. Several splices would need to be tested for statistically significant results (wild guess: ten each?). It would also help to have higher loads applied than can be induced between two winches.

What would be invaluable is knowing failure mode, and for this load testing equipment is needed.

SWL

[Seaworthy Lass]

We posted simultaneously .