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

[Seaworthy Lass]

Alan, I have looked at Premium's two videos again and filled in your table for them. I now feel like I am going cross eyed, so it all needs checking.

The differences between the methods are now glaringly obvious.

(Interesting, though it may not seem like it, it turns out that although the cover is only partially buried in the Premium method, the region up to R ends up lying roughly in the same spot relative to the core as the Samson method. This is not reflected in the data. The fact that so much core is cut off makes even less sense now though.)

Looking at Samson's video again, it only looks like about 1/3 of a fid of core is cut off at the end, so the difference to Premium's method is even more glaring.
Premium does, however, seem to bury a touch more cover than I first thought. I have added all that to the table.

I have also added a few rows to your table in red:
- T (SKIP THIS, I SEE YOU PUT IT IN LINE 7)
- Amount of core cut off
- Means of temporarily securing the crossover
- Whipping

Sorry, I am working on an iPad (google sheets) and have given up trying to attach the spreadsheet as you did.

SWL

[Alan Mighty]

Thanks, SWL.

I've incorporated your Premium Ropes data and I've worked through most of the Marlow instructions and started incorporating that data too. I want to watch the two Premium Ropes videos one more time and draw out a new set of diagrams of Marlow, Premium (old), and Premium (new).


I feel that Samson and Brion Toss belong in one group, and Marlow and the two Premiums in another.


All headache stuff.


I've read through Milne & A J McLaren again. It's a bit of fun: Katherine Milne originally did the work with A J McL as her supervisor (her project paper is on A J McLaren's project website). A J McL then corrected errors in her paper, did more tests, and added it all together to give Milne a publication with Milne as first author an A J McL as second author.


One of the key bits in that paper is the notion that a too short II- III distance can cause breakage of fibre and abrasion of fibres (Milne & McL refer to the II-III dimension as CD).


Here's two questions that are causing me headaches:


1. does the I-II dimension have a function with respect to strength and/or balancing the lengths of core and cover? Brion Toss has it at 8 diameters, Samson at 7 diameters. A tiny difference, 10 mm in 10 mm rope.


2. the tucked core is going to change its length. In your additions, you suggested that the length of core cut off and discarded in the Samson splice was 7 diameters. How did you arrive at that figure? I'm missing something. I've drawn and redrawn the Brion Toss splice trying to work out how much core will be cuts off (I think the Samson written description and video is clearer than Brion Toss's written description - but that may be just me).


I should be back with the expanded spreadsheet tomorrow my time (which is W Aus time, UTC + 8 at the moment).


I'd like to start, picking up another suggestion earlier in this thread, the idea of a 'more perfect' written instruction that includes additional notes about some of the steps. But that's even more hours of work.

[Seaworthy Lass]

Originally Posted by Alan Mighty

Thanks, SWL.

I've incorporated your Premium Ropes data and I've worked through most of the Marlow instructions and started incorporating that data too. I want to watch the two Premium Ropes videos one more time and draw out a new set of diagrams of Marlow, Premium (old), and Premium (new).

I will go through that again too with a clear head. It was predawn when I filled in those figures. All the columns started to merge after a while .

Originally Posted by Alan Mighty

I've read through Milne & A J McLaren again. It's a bit of fun: Katherine Milne originally did the work with A J McL as her supervisor (her project paper is on A J McLaren's project website). A J McL then corrected errors in her paper, did more tests, and added it all together to give Milne a publication with Milne as first author an A J McL as second author.

I still need to read that. Seems there are lots of gems in there.

Originally Posted by Alan Mighty

One of the key bits in that paper is the notion that a too short II- III distance can cause breakage of fibre and abrasion of fibres (Milne & McL refer to the II-III dimension as CD).

Very interesting. This confirms that insufficient bury of the cover tail in the core is not good. This is what Premium do.
By the way, did you see the note I made in red on your spreadsheet? As long as II-III is sufficiently long to bury the tail of the cover, then it is irrelevant how long it is. III is just an exit point and the cover will settle in the space II-III, as it needs to. So given Samson's 28 Ø is more than sufficient, there is no extra benefit from Toss making this 33 Ø. It just becomes critical if the distance selected is not long enough to bury the tail of the cover.

Originally Posted by Alan Mighty

Here's two questions that are causing me headaches:

1. does the I-II dimension have a function with respect to strength and/or balancing the lengths of core and cover? Brion Toss has it at 8 diameters, Samson at 7 diameters. A tiny difference, 10 mm in 10 mm rope.

Yes, I am sure it does affect strength, as it affects balance.
I doubt 1 Ø makes much difference though. These measurements are not that accurate. Remember Samson pull out the core and milk it then mark I to coincide with X. This is not where the core originally coincided with the cover at mark X. Your enthusiasm with milking will affect this postion more than 1 Ø.

Originally Posted by Alan Mighty

2. the tucked core is going to change its length. In your additions, you suggested that the length of core cut off and discarded in the Samson splice was 7 diameters. How did you arrive at that figure? I'm missing something. I've drawn and redrawn the Brion Toss splice trying to work out how much core will be cuts off (I think the Samson written description and video is clearer than Brion Toss's written description - but that may be just me).

I cannot calculate this. It is far too complex, as in some places the cover will be stretching in length (in the tail bury zone) in some shrinking (also in the tail bury zone), the core will be will shrinking in length when the cover is buried in it. It is a complex relationship.
All I can do is look at how much is cut off in the videos. Samson's was deceptive, as the rope is so thick. My first reaction of "it's about 2/3 fid" is incorrect if you look closely at the fid next to the bit being cut off (13:16 in the video). It is only 1/3 fid, so I marked that as 7 Ø in your table.

I tried to also estimate Premium's cut off length as carefully as I could and I decided in their first version it was about a fid length (not the fid lying in screen view at that stage, that was the small one and they used the normal one for measuring). In Premium's updated video it was a bit over a fid length. Then I looked at the relative size of the two fids they used in video 2 from a frozen image next to the scissors. If the "normal" one can be assumed to be 21 Ø, then the smaller one they actually used to determine the position of their marks was 16 Ø. That is how I arrived at some of Premium's figures.

This is a still shot of the amount of Samson's tail cut off. It is clear it is only around 1/3 fid, the same as the distance from the cut point to Z:

Originally Posted by Alan Mighty

I should be back with the expanded spreadsheet tomorrow my time (which is W Aus time, UTC + 8 at the moment).

I will be out all day Wed, back at about 18:00 UTC, so will look at them then. I still need to find time to go through the Marlow and Toss methods carefully. I have the latest edition of Brion Toss's "The Complete Rigger's Apprentice" (thanks again, Dockhead) so I want to look at that carefully too.

Too much to do, too little time .

[s/v Jedi]

Originally Posted by Seaworthy Lass

Very interesting. This confirms that insufficient bury of the cover tail in the core is not good. This is what Premium do.
By the way, did you see the note I made in red on your spreadsheet? As long as II-III is sufficiently long to bury the core, then it is irrelevant how long it is. III is just an exit point and the cover will settle in the space II-III, as it needs to. So given Samson's 28 Ø is more than sufficient, there is no extra benefit from Toss making this 33 Ø. It just becomes critical if the distance selected is not long enough to bury the core.

When insufficient bury is not good, it does not mean that the longer the bury, the better it gets. You seem to write that but also you state that the bury from Premium is insufficient. What we need to do is qualify "insufficient bury" and only then can we draw conclusions like that.

It is clear to me that you, like me, prefer the scientific approach and clear, detailed instructions. But keep in mind that the Europeans have been splicing rope since before the Americas and Australia were discovered and their methods have been proven. Same for these double braid splices, they have been done this way since double braid was developed. Much of what we do with tapering etc. has more to do with esthetics than with function, while the European methods are mostly function. They don't mess around with core tapering with the 1% or less improvement of strength... because it is time consuming and strong enough without that. I believe my boat was initially rigged by Nance & Underwood (Americans) and it had these European splices as well.

Here is the Marlow splice video and you can see the smaller fid for the core again as well as a very inaccurate core bury without any tapering and a rough taper of the cover:

https://www.youtube.com/watch?v=xUfVd2QExQo

[Seaworthy Lass]

Originally Posted by s/v Jedi

When insufficient bury is not good, it does not mean that the longer the bury, the better it gets. You seem to write that but also you state that the bury from Premium is insufficient. What we need to do is qualify "insufficient bury" and only then can we draw conclusions like that.

Yes, that is correct . I agree fully. I jumped in with the "insufficient'" comment hastily.
To complicate things, that "bury" is twofold. Variable lengths of tail could be buried in the cover (ie the magical fid length need not be selected) and then variable amounts of this could, in addition, be buried in the core.

Then there is the effect of length of bury of the core that needs to be considered. This buries in the regions of RX and XZ. As far as I am aware, the effect of different proportions as well as lengths on splice strength has not been fully examined.

I think the studies Alan gave links to probably only touched on some of these factors (the scope of this is huge), but I have only had a chance to read one of those papers.

Originally Posted by s/v Jedi

It is clear to me that you, like me, prefer the scientific approach and clear, detailed instructions. But keep in mind that the Europeans have been splicing rope since before the Americas and Australia were discovered and their methods have been proven. Same for these double braid splices, they have been done this way since double braid was developed.

Yes, I do like the scientific approach . There is a lot of "art" in knotwork, but underlying this are reasonably repeatable measurements of strength. Splices are no different if executed with care.

Jedi, splicing hemp is very different to splicing polyester, which is vastly different again to UHMWPE. Knots do not work universally and neither do splices. We have no "proven" methods when it comes to new fibres. Splices currently break and they break regularly.

Originally Posted by s/v Jedi

Much of what we do with tapering etc. has more to do with esthetics than with function, while the European methods are mostly function. They don't mess around with core tapering with the 1% or less improvement of strength... because it is time consuming and strong enough without that.

Sorry, I do not believe this is correct. Lack of taper will decrease line strength by about 20% using single braid dyneema. Full line strength is achievable otherwise. As far as I am aware, there is nothing to suggest tapering has only less than 1% impact on the strength of double braid polyester splices.

Originally Posted by s/v Jedi

Here is the Marlow splice video and you can see the smaller fid for the core again as well as a very inaccurate core bury without any tapering and a rough taper of the cover:

The smaller fid is not used for any measuring, so that is not an issue.
I wouldn't call the core bury "inaccurate" it is just that the markings are a little "haphazard" .
Yes, the taper cover is rough, but at least there is some taper, unlike Premium who only cut the end off at an angle. I don't know how much this weakens the splice. Samson go to extraordinary lengths to taper the cover well. I doubt they are doing this purely for aesthetic reasons.
As you can imagine, I nearly fainted seeing how much core Marlow cut off. You have a wicked streak posting that link .

Having seen the video I will sort out estimated measurements for Alan's table.

SWL

[Juho]

Few more comments coming. I'll concentrate on making the splices understandable.

The spreadsheet approach of Alan Mighty is good. It makes comparison of different methods and picking up your favourite method (or building your own) easy. Having tapering and stitching as separate topics improves the structure.

The Milne and McLaren cross-section drawing is good since it makes it easy to understand what the final product is intended to be like.

To me it fees natural to present also the names of different points in that drawing. During the process I renamed the points in order to understand better the logic of the splice (see drawing below). Those names are not necessarily the best ones. I just want to point out the symmetry of names and points in the cover and core, and demonstrate that descriptive names / abbreviations of the points may be useful.

L = start of the Loop
R = Return from the loop
C = Crossover of cover and core
E = End of rope
X = eXit point

In the drawing points L, L', R and R' are always at the same place in the final splice. Points C and C' should be placed some small distance to the left, usually (but not necessarily) right next to each others. Points E and E' should be far enough to the left to generate sufficient friction (or base for stitching). Often E and E' are intentionally not at the same place. Points X and X' should be little bit to the left of E and E' respectively.

Based on this analysis the key differences in markings and structure of the final splice are length of the loop (L↔︎R), length of R↔︎E, length of R'↔︎E', length of R↔︎C, and length of C↔︎C'. I guess these values are sufficient to describe the proportions of all possible splices of this type (excluding tapering and stitching/whipping options).

I read the spreadsheets in this light. Row Taper/Crossover means the same as R↔︎C. Row Reference is equal to R↔︎E. Row core eXtract is L↔︎R + R↔︎E. This row is not really needed if Reference (R↔︎E) is already given, length of eye can be whatever, and the formula is always "R + eye". Row Z is L↔︎X. Row I refers to L'. This row has no value since the position of L' is determined by practical means (e.g. next to L after milking the rope). If this is always the case, this row may not be needed (or maybe for mentioning if rope was properly milked or not). Row II is L'↔︎C'. In the previous paragraph I used C↔︎C' to describe the position of C'. When making the marks in the rope, R'↔︎C' is needed. Value C↔︎C' is not intended for making the splice but for evaluating the resulting splice. Row III is C'↔︎X'.

The spreadsheet thus covers all the key values that I described above (and thus all possible variants of the splice). My R'↔︎E' can be derived from row III / C'↔︎X' (R'↔︎E' is equal or slightly shorter than L'↔︎C' + C'↔︎X'). The exit points (X, X') are needed when making the splice, but they can be forgotten when evaluating the final product. I note that the values (lengths) may be slightly different when making the splice, and when evaluating the final product (because of changes in length due to different radius' in different parts of the rope).

Stitching eliminates the possibility of splice slipping open. It becomes more important to milk the ropes and measure the distances accurately. If that is not done properly, it is possible that either the cover or core will take all of the load, or that the size of the loop will not be as planned.

In the Samson video C and C' were probably very close to each others in the final splice, as shown in the drawing of SWL's mail #47 (named T and 2). In the Sailrite video of s/v Jedi's mail #52 C and C' are stitched together so that they can not separate. In splice of the Premium video of mail #1 the distance between C and C' probably grew when the rope was milked. If one does not milk the rope with good load before shortening the core, there is a risk that the core will dive too deep (leading to short R'↔︎E') when the rope is loaded later (and C and C' move apart).

In a loop the load is divided in two parts. Therefore it may be ok to cut half of the threads away, as for example from the core in the Samson video of mail #1.

There are at least two kind of stitching. In the Samson style stitches cover a considerable length of the rope. In the Sailrite style stitches are at one spot but from many directions. If the stitches are expected to carry part of the load too, they should be somewhat loose at the start, or at least flexible so that the thread can move so that the load will be shared evenly by multiple stitches when under load. The Samson style may make better use of the whole length of the rope ends (good milking needed).

I guess that is enough for now. I may return with comments on tapering and stitching. Maybe on different methods too.

[Seaworthy Lass]

Juho, I agree fully regarding the labelling protocol . I have just started looking at the Marlow measurements and because Mark I is made further from the end than X (as it is in the Sampson video) it really is necessary to have a start point. I was calling that E .

SWL

[Seaworthy Lass]

I will draw out your labels in a moment to make it clear.

I think (hope ) Alan will agree to modify his table, as what you suggest is very logical.

SWL

[s/v Jedi]

SWL, we're talking about a double braid splice in polyester, right? It is well known that a Dyneema single braid needs the tapering, but you really can't deduct that the same principle is valid for other materials.

Here is a good example; a core-only splice vs a double-splice in double braid. They test it to destruction... which splice wins?

The Splicing Test, Which is Stronger?

check out their splicing instructions. All that is "good enough" :-)

[Seaworthy Lass]

Originally Posted by s/v Jedi

SWL, we're talking about a double braid splice in polyester, right? It is well known that a Dyneema single braid needs the tapering, but you really can't deduct that the same principle is valid for other materials.

Here is a good example; a core-only splice vs a double-splice in double braid. They test it to destruction... which splice wins?

The Splicing Test, Which is Stronger?

check out their splicing instructions. All that is "good enough" :-)

Hi Jedi
Thanks for the links.
Very interesting .

SWL

[s/v Jedi]

And let's not forget Yale Cordage. Their splice is in the Samson corner and it looks like it didn't change for decades:

http://www.yalecordage.com/pdf/yale_indust_dbraid.pdf
Also, recommended for all double braid splices:
http://www.yalecordage.com/pdf/yale_whiplock.pdf

About history: polyester double braid was invented in the 50's by Samson. That's 65 years of experience which should be enough to find which splices do not work. I believe that every splice described is better than 90% of rope strength.

Did you know Dyneema is a Dutch invention? DSM invented and produces all Dyneema. They recommend 60x diameter for the bury for coated Dyneema and 100x diameter for uncoated Dyneema.

[Seaworthy Lass]

Juho, I have placed your marks on loose core and cover, as it would be laid out before splicing.

My only comment is that X need not be way over to the left in your diagram. It can be much closer to R I think, as the total bury of the core affects the grip and that included the loop (as you mentioned earlier).

We need two more points marked on your diagram I think.

P is not needed on the spreadsheet, but needs to be marked on the core in practice, so something is needed there. It also makes E'C' easily measurable, as C' is marked on the core and PC' is usually given.
E'S is useful I think, as when compared to RX, it gives some indication of how mismatched the core and cover are.

Do you think these two extra points are needed and if so what would you like to name them? I have suggested P and S, but it goes against marking everything on the core with a '

SWL

[Seaworthy Lass]

For the Marlow method:

EL = 1 fid = 21 Ø

RX = 3cm = 3 Ø in this case

PC' = 2/3 fid = 14 Ø

C'X' is unknown, but instructions say to make it long enough to bury the cover tail, so can just be marked OK

LC = 0 therefore EC (amount of bury of cover tail) = 21 Ø

E'P = estimated ER + 4 Ø
It is in excess of ER, as a bit of core is pulled out initially, then when it is extracted it is marked after a bit more core has been pulled out.

E'S (amount cut off) = estimated 27 Ø.
It ends up this long, as E'P was 4 Ø longer than E'P to start with and 14 Ø was added and RX was only 3 Ø.

SWL
PS Juho, I am getting too tired to sort it all out as you presented. I will leave Alan to alter his labelling and then just read off whatever he wants from the above.

[Juho]

Here's one description of how to measure and mark the points. The idea is to allow the user to freely select the parameters.

1) Decide R↔︎E and mark R
2) Decide R↔︎L (loop size) and mark L
3) Decide R'↔︎E' and mark X (R'↔︎E' plus some extra from L)
4) Decide R↔︎C (usually a short distance) and mark C
5) Make the milking knot far enough, extract core at L, milk and mark L' (at L)
6) Decide C↔︎C' (usually as short as possible) and mark C' (R↔︎C + C↔︎C' from L')
7) Mark X' (bit further than R↔︎E from L')
8) Insert cover to core from C' towards X', taper it and make distance C↔︎C' correct
9) Insert core to cover from C towards X
10) Milk and stretch to reach the final shape, taper and shorten the core before or close to the end of this step, and stitch before and after and whip if needed

The important decisions are made at steps 1, 2 and 3. Decisions at steps 4 and 6 are more trivial.

At step 1 we assumed that there will be no need to shorten the cover due to need to have a super long core (that would be very unusual).

At step 3 the required extra length is not quite trivial to estimate (diameter of the cover grows and may make it shorter than expected). No problem to mark it a bit too far.

At step 4 marking point C is done before core is extracted from the cover. That may make measurements a bit more accurate.

At step 7 it is a bit easier to estimate the required extra bit than it was at step 3. No problem to mark it a bit too far.

At step 8 distance C↔︎C' can be left too short but not too long (milking and stretching will fix it). The crossover point may be taped/fixed.

Concrete markings are not really needed at all locations. One may quite well estimate the location of some of them (X, X', L, R, C', C). One could even mark L' by keeping one's thumb at it for a while.

I should try these with a real rope but I don't have any available right now.

[Juho]

Originally Posted by Seaworthy Lass

Juho, I have placed your marks on loose core and cover, as it would be laid out before splicing.

My only comment is that X need not be way over to the left in your diagram. It can be much closer to R I think, as the total bury of the core affects the grip and that included the loop (as you mentioned earlier).

We need two more points marked on your diagram I think.

P is not needed on the spreadsheet, but needs to be marked on the core in practice, so something is needed there. It also makes E'C' easily measurable, as C' is marked on the core and PC' is usually given.
E'S is useful I think, as when compared to RX, it gives some indication of how mismatched the core and cover are.

Do you think these two extra points are needed and if so what would you like to name them? I have suggested P and S, but it goes against marking everything on the core with a '

SWL

Yes, X can be wherever one wants them to be (with E'). The drawing is generic. I drew E' further to left than E because the core would reach further to the left than cover if it is not shortened or shortened only moderately.

In the figure L and R have changed place. And L' and R' on the other side.

If the P point is the one that is marked after (or before) the core is extracted and the whole rope milked, I think it should be the same as L' (that should be at the R' position in the figure because L' and R' were swapped).

In my drawing the splice is shown after the core has been shortened. In your drawing the core is still in its original length, I believe. If so, E' of my drawing should maybe refer to the S point of your drawing. The end of the core (including the point that is named E' in your drawing) is missing. I don't know how to draw the cut off part of core in my drawing. In your drawing the end of core could be named E'' (or S or whatever). Or what would be the best way to name the original and shortened end of the core (and match the drawings where the core is in its original length vs. shortened)?