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

[skipmac]

Originally Posted by Stumble

The X is evil evil stuff. Not only is it a pain to splice (and has its own splicing instructions), but it is also really stiff and has a terrible hand. For the minimal stretch reduction compared to sta-set it isn't worth it.

I agree, evil.

I tried splicing Sta-set x and read all the instructions and watched all the videos and after two very bad results that took hours of my life decided I didn't have enough time to do a proper splice. Maybe when I'm fully retired and have all day to fool around with rope I'll give it another go.

[Seaworthy Lass]

Originally Posted by markwesti

The instructions that come with the Selma fids are a translation and at least for me a little hard to understand . I need more practice .

Hi Mark

It will help tremendously if you mark the core and cover before you start.
This can be done in 3 steps.

I have followed Samson's YouTube for double braid polyester splicing (=Class 1 line), but marked line diameters rather than "fid lengths", as "fid lengths" are confusing if you are using homemade fids.
I have used 21 x line diameter to correspond to 1 "fid length", as Samson specify.

I will attach the three steps, then the next step will show how to put it all together.

Watch the Samson YouTube for full details.

SWL

Step1:
Decide how big you want the eye of the loop to be.
Mark the cover at R, X, Z then T and every 5th pair past T (tapering marks):

[Seaworthy Lass]

Step 2:

Tie a knot in the line roughly 100 line diameters away.

Place Mark 1 on the core as it emerges from X after you have pulled and milked the core to realign them.
The core will end up just a touch longer. Work harder on your milking if it is significantly longer.
(See Sampson video for details)

The green is the cover, the orange is the core.
This is how it will look when you have done this:

[Seaworthy Lass]

Step 3:

Pull the core out lots.
Place Mark 2 and Mark 3 on the cover as indicated:

[Seaworthy Lass]

Step 4:

Pull out a bit more core. It makes it much easier to see what you need to do if you lay it out as shown below, rather than how Sampson lay it out (just my opinion).

Basically you just need to do a long splice - join the core and cover together at points T and Mark 2, feeding the cover in the core one way first, emerging at Mark 3 (then after tapering it pull it back and tape the junction), then feeding the core in the cover the other way emerging at Z, milking it well, marking it, tapering it, then cutting it at the mark and milking it back.

Easy peasy .

Then you need lots of strength and a little finesse and you milk the cover all the way from the distant knot until X and R meet (eye is then the size you wanted. Remember to remove the joining tape. Again, watch the Samson YouTube for clarity.

Stitch the junction.
Yeah! You are done.

SWL

[markwesti]

WOW SWL , I really appreciate the time you have taken . I just got back from the boat with my rigging bag and a load of line . We are about to have some rain so I'm really going to get into it . The line is New England Sta-Set and is half inch , I find larger line is easier to work . Again thank you for the time . m.

[Seaworthy Lass]

Originally Posted by markwesti

WOW SWL , I really appreciate the time you have taken . I just got back from the boat with my rigging bag and a load of line . We are about to have some rain so I'm really going to get into it . The line is New England Sta-Set and is half inch , I find larger line is easier to work . Again thank you for the time . m.

You're welcome. I hope to hear your next splice is successful. Just mark it all out in rope diameters as shown and connect T on the cover with Mark 2 on the core, burying each way from that point and you can't go wrong.

It has been beneficial for me as well.
The first time I watched the YouTube I just couldn't figure out the geometry at all. It slowly became clearer. Drawing it out really crystallised it .

SWL

[jcapo]

Toss's instructions are easy to use, IMO.

http://briontoss.com/education/BTR_book.pdf

[StuM]

Originally Posted by Seaworthy Lass

Thanks for looking at this and responding Stu . I find it interesting and challenging working out the logistics. It greatly helps my understanding. I find this stuff fascinating.

OK, I see the difference now.

Samson ends up with the crossover point where the eye re-enters the cover and then has a full fid of (cover buried in core) buried in the cover.

Premium bury the crossover point about 1/2 a fid past this point.
You still have a full fid of cover buried but it is 1/2 fid of (cover buried in core) and 1/2 fid of (core buried in cover) buried in the cover.

(Take a look at 3:35 on the Premium video and see how far the crossover point is from the mark "A"). All of that gets buried as well as the (cover buried in core).

So in the end, they both have pretty much the same amount of bury, the difference is where the crossover point ends up and exactly what is buried in what at the various points.

Samson has it all as (cover in core in cover). Premium has half as (cover in core in cover) and half as (core in cover in cover).


I've got a couple of genoa sheets that I'm going to do today for the 1/2 tonner I race on at weekends, I'll try the Premium method on them and see how they go over the next couple of races.


Possibly Mark's problem is that he has not been burying the crossover point deeply and has ended up with an eye much larger than planned.

[Seaworthy Lass]

Originally Posted by StuM

I've got a couple of genoa sheets that I'm going to do today for the 1/2 tonner I race on at weekends, I'll try the Premium method on them and see how they go over the next couple of races.

Hmmmm, racing! Lots at stake .
Are you confident enough in the Premium method to try this on your genoa sheets for a season without locking stitches? The stitches are just added security for good eye splices, the splice should not depend on them.


Stu, I am persisting, as I think you like "puzzles" like this as much as I do (or at least I hope you do, otherwise you will think me a PITA ). For me, analysing this is equivalent to the pleasure others get from completing crosswords or sudoku.

Originally Posted by StuM

OK, I see the difference now.

Samson ends up with the crossover point where the eye re-enters the cover and then has a full fid of (cover buried in core) buried in the cover.

Premium bury the crossover point about 1/2 a fid past this point.
You still have a full fid of cover buried but it is 1/2 fid of (cover buried in core) and 1/2 fid of (core buried in cover) buried in the cover.

(Take a look at 3:35 on the Premium video and see how far the crossover point is from the mark "A"). All of that gets buried as well as the (cover buried in core).

So in the end, they both have pretty much the same amount of bury, the difference is where the crossover point ends up and exactly what is buried in what at the various points.

Samson has it all as (cover in core in cover). Premium has half as (cover in core in cover) and half as (core in cover in cover).

Yes, we agree here .
The crossover is occurring much further away from the eye in the Premium method.
And yes, the amount of bury of the cover is exactly the same for the two methods (see my diagram in post #8), it is just what the core is doing in that region that is different.


The story doen't end though. The Premium method is cutting off way more of the tail of the core. It is this that I really object to. The length being cut off in the Premium method is what bothered me so much when I first saw the YouTube. I couldn't figure out why it is reasonable to do this. After a day mulling over it, I still think it is unreasonable to cut this much off, and am more confident of this.

I will see if I can draw a diagram to explain this.

Best wishes during the race with your new splice trial. I actually wouldn't want this to fail on you just to prove a point, so take care .

SWL

[Alan Mighty]

Originally Posted by Alan Mighty

Please tell me more, LakeSuperior. Where can I find good instructions for low stretch polyester double braid meant for halyard?

Originally Posted by LakeSuperior

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

Thanks for clearing that up.


What you have linked to is a splice for Class 2 double braid, one for core-dependent double braid. That is double braid with a high modulus core, such as using Dyneema, with the rope constructed so the core takes the load and the cover protects the core from abrasion, UV and so on.


What SWL's thread deals with is a splice for Class 1 double braid, the splice you would use with a balanced double braid, built so the load is shared between cover and core. Polyester double braid, also called 'polyester braid on polyester braid', is a good example.


Class 1 double braid, polyester double braid, can also be low stretch.


Not as low stretch as a Dyneema-cored double braid, but good enough for halyards for smaller boats, such as my 33 ft cruiser Led Myne.


Consider for example Langman Ropes' Newport polyester double braid. In 10 mm (3/8") diameter, it has a breaking load of 3000 kg.force, a linear mass of 7.5 kg/100 metre, and an elastic elongation of 1.5% at 20% of BL, meaning about 600 kg.f.


A not so good (if I have my stats and math right) US example is Samson Ropes' XLS, which in 3/8" diameter has a BL of about 4400 lb.force (2000 kg.f), a linear mass of 4.3 lb/ft about 6.41 kg/100 m, and an elastic elongation of 2.2% at 20% of BL, meaning at about 400 kg.f.


Note the linear mass: heavier rope means more polyester which means less elongation. Air entrapped in the braid weave does not resist stretching, it seems. Funny that.


Estimating the load on a halyard is not easy. See Herb Benavent's discussion at: https://www.riggingdoctor.com/life-a...-halyard-loads


As Benavent noted, Brion Toss provided a quick guide to halyard loads with a simple (and undocumented) curve in his "Complete Riggers Apprentice". Using that, I figure the max load on Led Myne's halyard is around 750 kg.f / 1650 lb.f. That means that even one of the best polyester balanced double braids, Langman's Newport, is liable to more than 20% load (and hence elongation) if I don't reef early.


From those figures, you can see why Samson and other rope makers have invested in a big way in HMPE core-dependent double braid.


And you can see why racers, especially well-funded ones, much prefer a Dyneema cored line. A racer will happily push her gear to the limits, having budgeted to replace the halyard (and other lines) and the sail in a relatively short time.


But for cruisers with smaller boats, such as Led Myne, have advantages in staying with polyester double braid for halyards. For one, putting a HMPE halyard on a polyester (e.g. Dacron fabric) sail means that the sail is more likely to elongate than the halyard. So letting the halyard stretch is somewhat protective of the sail.


For another, uncertainty continues about the longevity of HMPE (e.g. Dyneema) cores when subject to a tight bend. A tight eye slice to the shackle, a longer eye splice cow-hitched to the shackle, or an medium-size eye splice protected by a thimble are among the easy ways to make a halyard to its shackle. The tight bends involved in the first two may put a Dyneema core under stress. But polyester double braid seems unaffected. The usual workarounds for Dyneema-cored double braid are to leave the cow-hitch naked (i.e. strip the cover) so fibre breakage can be seen, or just to replace the splice (or retire the whole line) on a regular schedule.


So for a cruiser aiming to spend years away from ready access to new cordage, a low stretch polyester double braid has advantages.


The question then is what splicing technique for Class 1 double braid is the best. SWL's thread addresses two problems: (1) multiple different techniques, some slight variation, some involving big differences; and (2) the potential for confusion in those techniques.


Little has been done to test the strengths of the different techniques for Class 1 double braid eye splices.


Heather McLaren, when an undergraduate student mechanical engineer at Strathclyde University, wrote a paper testing slight length variations of the Marlow's recommended splice (see Marlow's description and video at https://www.marlowropes.com/splicing-instructions; see McLaren's paper at http://personal.strath.ac.uk/andrew....per%202013.pdf). McLaren concluded that the length of the bury of the splice was not the critical factor.


Bob Norson gained some notoriety for his qualitative test of two polyester double braid splice techniques he followed. See his test at: The Splicing Test, Which is Stronger?


Norson's work was interesting even if not scientific. He took apart a professional UK splicer's work and reverse engineered it. And discovered that it did not follow the canonical technique of Marlow/Samson etc. Norson then devised two much simpler splices, the 'Norson Splice' and the 'Norson Double Splice'. You can see all three of those splices by following the links at the top of his ropetest page.


Professional splicers criticised Norson, arguing that he had lost the balance between core and cover as shown by where the rope broke. Funny that McLaren's ropes, spliced as per Marlow's technique, broke in much the same locations.


So far we lack a quantitative comparison between a simpler splice, such as the Norson Double Splice, and one of the canonical ropemaker recommendations (Marlow, Samson etc).

[Alan Mighty]

Originally Posted by Seaworthy Lass

The Premium method is cutting off way more of the tail of the core. It is this that I really object to. The length being cut off in the Premium method is what bothered me so much when I first saw the YouTube. I couldn't figure out why it is reasonable to do this. After a day mulling over it, I still think it is unreasonable to cut this much off, and am more confident of this.

I will see if I can draw a diagram to explain this.

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).

[StuM]

Originally Posted by Seaworthy Lass

Hmmmm, racing! Lots at stake .
Are you confident enough in the Premium method to try this on your genoa sheets for a season without locking stitches? The stitches are just added security for good eye splices, the splice should not depend on them.

Didn't do it in the end. When I got a look at the new sheets, they are not Class 1. They are core dependent braid (polyester braid over dyneema braid core) and apart from anything else, the cover was too tightly woven to bury (core + cover) along with the core inside the cover

[Alan Mighty]

Originally Posted by Alan Mighty

Little has been done to test the strengths of the different techniques for Class 1 double braid eye splices.

Mea culpa. I forgot to mention the earlier work: www.paci.com.au/downloads_public/knots/15_Report_knot-terminations_2006.pdf

[Seaworthy Lass]

Originally Posted by Alan Mighty

Thanks for clearing that up.


What you have linked to is a splice for Class 2 double braid, one for core-dependent double braid. That is double braid with a high modulus core, such as using Dyneema, with the rope constructed so the core takes the load and the cover protects the core from abrasion, UV and so on.


What SWL's thread deals with is a splice for Class 1 double braid, the splice you would use with a balanced double braid, built so the load is shared between cover and core. Polyester double braid, also called 'polyester braid on polyester braid', is a good example.


Class 1 double braid, polyester double braid, can also be low stretch.


Not as low stretch as a Dyneema-cored double braid, but good enough for halyards for smaller boats, such as my 33 ft cruiser Led Myne.


Consider for example Langman Ropes' Newport polyester double braid. In 10 mm (3/8") diameter, it has a breaking load of 3000 kg.force, a linear mass of 7.5 kg/100 metre, and an elastic elongation of 1.5% at 20% of BL, meaning about 600 kg.f.


A not so good (if I have my stats and math right) US example is Samson Ropes' XLS, which in 3/8" diameter has a BL of about 4400 lb.force (2000 kg.f), a linear mass of 4.3 lb/ft about 6.41 kg/100 m, and an elastic elongation of 2.2% at 20% of BL, meaning at about 400 kg.f.


Note the linear mass: heavier rope means more polyester which means less elongation. Air entrapped in the braid weave does not resist stretching, it seems. Funny that.


Estimating the load on a halyard is not easy. See Herb Benavent's discussion at: https://www.riggingdoctor.com/life-a...-halyard-loads


As Benavent noted, Brion Toss provided a quick guide to halyard loads with a simple (and undocumented) curve in his "Complete Riggers Apprentice". Using that, I figure the max load on Led Myne's halyard is around 750 kg.f / 1650 lb.f. That means that even one of the best polyester balanced double braids, Langman's Newport, is liable to more than 20% load (and hence elongation) if I don't reef early.


From those figures, you can see why Samson and other rope makers have invested in a big way in HMPE core-dependent double braid.


And you can see why racers, especially well-funded ones, much prefer a Dyneema cored line. A racer will happily push her gear to the limits, having budgeted to replace the halyard (and other lines) and the sail in a relatively short time.


But for cruisers with smaller boats, such as Led Myne, have advantages in staying with polyester double braid for halyards. For one, putting a HMPE halyard on a polyester (e.g. Dacron fabric) sail means that the sail is more likely to elongate than the halyard. So letting the halyard stretch is somewhat protective of the sail.


For another, uncertainty continues about the longevity of HMPE (e.g. Dyneema) cores when subject to a tight bend. A tight eye slice to the shackle, a longer eye splice cow-hitched to the shackle, or an medium-size eye splice protected by a thimble are among the easy ways to make a halyard to its shackle. The tight bends involved in the first two may put a Dyneema core under stress. But polyester double braid seems unaffected. The usual workarounds for Dyneema-cored double braid are to leave the cow-hitch naked (i.e. strip the cover) so fibre breakage can be seen, or just to replace the splice (or retire the whole line) on a regular schedule.


So for a cruiser aiming to spend years away from ready access to new cordage, a low stretch polyester double braid has advantages.


The question then is what splicing technique for Class 1 double braid is the best. SWL's thread addresses two problems: (1) multiple different techniques, some slight variation, some involving big differences; and (2) the potential for confusion in those techniques.


Little has been done to test the strengths of the different techniques for Class 1 double braid eye splices.


Heather McLaren, when an undergraduate student mechanical engineer at Strathclyde University, wrote a paper testing slight length variations of the Marlow's recommended splice (see Marlow's description and video at https://www.marlowropes.com/splicing-instructions; see McLaren's paper at http://personal.strath.ac.uk/andrew....per%202013.pdf). McLaren concluded that the length of the bury of the splice was not the critical factor.


Bob Norson gained some notoriety for his qualitative test of two polyester double braid splice techniques he followed. See his test at: The Splicing Test, Which is Stronger?


Norson's work was interesting even if not scientific. He took apart a professional UK splicer's work and reverse engineered it. And discovered that it did not follow the canonical technique of Marlow/Samson etc. Norson then devised two much simpler splices, the 'Norson Splice' and the 'Norson Double Splice'. You can see all three of those splices by following the links at the top of his ropetest page.


Professional splicers criticised Norson, arguing that he had lost the balance between core and cover as shown by where the rope broke. Funny that McLaren's ropes, spliced as per Marlow's technique, broke in much the same locations.


So far we lack a quantitative comparison between a simpler splice, such as the Norson Double Splice, and one of the canonical ropemaker recommendations (Marlow, Samson etc).

Alan, fantastic post!
Many thanks .

This is a classic example of why CF is absolutely priceless at times. To be able to access information, chat about issues, have calculations checked, and to bounce ideas back and forth is invaluable.

A lot of can come out of this, if only to deepen understanding. Advances are also possible and have occured in the past, both on CF and other sailing forums such as SA.

I am about to read Heather McLaren's paper, so will respond more later.

SWL