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Mid-line eye-splice in single braid?


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I want to splice an eye into the middle of a line (for pre-tensioning a backstay adjuster on a Melges 24).

I've seen this done but cannot find any information on doing it correctly.  Seems like you want it locked (brummel-ish) in some way.

Anyone have a link or high level idea of best approach?

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47 minutes ago, tanzer1645 said:

I want to splice an eye into the middle of a line

is the line going to be a "V" with the splice at the peak, or is it "in-line" (eg straight with the spliced loop just hanging out sideways)?

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that's a difficult application to maintain high strength because you have two load path's thru the splice.

I have not tested this, but I guess the best solution would be to take some spare single braid , Put a normal eye splice on one end, and take the other end and just long bury (with nice taper) up into the main line.  That will give you a good load path for both the bitter end loading and the added loop loading.  That is quite easy to do and  around 85% strength (the strength loss comes at the stress riser where the added loop is inserted into the main line).

edit: I hope that is clear, it is not at all complicated . .  .but if my writing sucks, I could make one with pictures if you needed :)

You can do it by putting a multiple Brummel in the line, but the load path will be fucked when you load the bitter end and probably be only 50% strength.

There is a knot - the alpine butterfly, which does this exact thing you want, and would ofc be dead easy, but again only 50% strength

 

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Interesting - one note is that the really hard loading will only be when using the mid-line loop (heavy wind mode) - so maybe the multiple brummel would not be so bad (if it means bury does not need to be as long and its locked).  Also since its a the backstay bridle, its mostly loaded 2:1-ish - and a much larger line than the standing segment that takes it 1:1.

Will play with this - thanks!

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So you don't currently really have enough throw in the system between strong and light breeze?

We have that on a dinghy vang and mainsheets strop.  We just make a large spliced loop on one end of the first part of the purchase with the tail of the splice hanging out and an overhand knot in the end so it can't pull out. Just expand or shrink the loop to change the length. No second eye.

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when the added loop is loaded, the inserted loop and the multiple brummel (you need to do like 5 brummel crosses to get this) will each be roughly the same strength (like 85%)

an end loop brummel can be a bit higher (like 90-95% strength) because you can bury the tail which will carry some load, but in your application the Brummel's are going to take all the load and they distort the weave . . .so 85% (this I have tested)

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22 minutes ago, European Bloke said:

a large spliced loop on one end of the first part of the purchase with the tail of the splice hanging out and an overhand knot in the end so it can't pull out. Just expand or shrink the loop to change the length. No second eye.

essentially the adjustable end of a  whoopie sling

I've never seen them used in a high load application.  The exit point creates about a 20% strength loss (so 80% strength).  If the bury is long enough it should have high strength in steady state loads, but I would be a bit worried about cyclic loading causing it to creep . . but I have never tested it - long enough it could well be perfectly fine.

 

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If you really want an eye just hanging out I'd say long bury a spliced eye in as estarzinger suggests, or you can find the wicked splice instructions where you braid the spliced eye into the standing part.

 

But another way would be to splice the bridle to the short length with a slightly longer eye, and then splice a second piece, eye to eye for the long length. you'd have full strength eye splices everywhere.

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9 minutes ago, mgs said:

But another way would be to splice the bridle to the short length with a slightly longer eye, and then splice a second piece, eye to eye for the long length. you'd have full strength eye splices everywhere.

yea, that would be another good solution.  only downside I can see would be when the bitter end is loaded the upper loop is also loaded, so would be stretched tight and hard to clip into it - with the inserted loop approach the upper loop is just dangling there and unloaded and easy to clip to or pull on.  Idk if that is an issue for this application or not.

 

edit and i guess you could solve that by putting a second much smaller end to end loop thru the upper loop, which would just dangle free when the big end loop is loaded and give you an unloaded attachment point for the upper loop.

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2 hours ago, estarzinger said:

yea, that would be another good solution.  only downside I can see would be when the bitter end is loaded the upper loop is also loaded, so would be stretched tight and hard to clip into it - with the inserted loop approach the upper loop is just dangling there and unloaded and easy to clip to or pull on.  Idk if that is an issue for this application or not.

 

edit and i guess you could solve that by putting a second much smaller end to end loop thru the upper loop, which would just dangle free when the big end loop is loaded and give you an unloaded attachment point for the upper loop.

well sure, if you want to worry about details...

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2nd length with eye-loops - love that and so obvious!

mgs - good point on the attach-while-loading, luckily in this application when I'm switching there is no load (at that point the backstay flicker is taking up slack).

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Not sure I followed all the above good ideas. Forgive me if...  If the higher 'dangly' loop is the heavily loaded of the pair then make it from the standing part. The longer lighter loaded part can be the separate (spliced in) line. I'd bury the high load dangly one inside the longer part...except for tucking the very end in...bcuz that is the way the burys work.

Is ultimate breaking strength a factor in this backstay. Probably not with modern line. So strength losses at splices may not be as worrisome as creeping splices.

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As mentioned above the common practice on M24s is to take wraps around the outboard bracket pegs.

On boats like the M32 they use a loop and spliced eye on the deadend with something like a snap shackle or dogbone attached to the boat. In light air the loop is part of the backstay when windier the dogbone/shackle gets clipped to the spliced eye so the loop is removed from the system and viola the backstay is shorter

 

 

 

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I'd suggest the long buried-eye as others have done - I've used these to create similar 'hobble loops' on a variety of boats.

I was chatting to a professional rigger last week (multiple Volvos and new build superyachts so really not fucking about) and asked him if they ever used locking splices instead of long-bury... his response was always long-bury, for a locking splice 'you may as well just tie a knot in it'. 

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4 hours ago, NZK said:

I'd suggest the long buried-eye as others have done - I've used these to create similar 'hobble loops' on a variety of boats.

I was chatting to a professional rigger last week (multiple Volvos and new build superyachts so really not fucking about) and asked him if they ever used locking splices instead of long-bury... his response was always long-bury, for a locking splice 'you may as well just tie a knot in it'. 

That's interesting to hear. How long is a long bury and what's the problem with locking splices? Just putting as much torture into the line as a knot? Does he whip the long bury?

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1 minute ago, European Bloke said:

That's interesting to hear. How long is a long bury and what's the problem with locking splices? Just putting as much torture into the line as a knot? Does he whip the long bury?

It seems to vary but I think about 70 times the line diameter is overly safe (so a 6mm line has 420mm bury) - I think he often does less but wasn't specific about it. Taper the bury gradually from about halfway and then whip just under the eye to stop the eye 'creeping' when not under load. 

As I understood it the reasoning against the locking splice was just as you said - with the locks you're splitting the braid and creating load points whereas the long-bury is a smooth distribution of load. They're a whole lot quicker too...

Here's a little one he was working on when I called by...

1304479757_eyesplice.jpg

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1 hour ago, NZK said:

 

Here's a little one he was working on when I called by...

1304479757_eyesplice.jpg

 

Not to complicate things, but I know of one rope manufacturer that recommends a braidback splice on double braid splices over 3/4" and single braid over 1" for dyneema/aramid/vectran/etc...

uses only 40x the rope diameter for the splice.

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Pre-2017 a lot of yacht riggers thought Brummel locks were near full strength and they were all in fashion. Then there was a fatality on a clipper yacht (2017) caused by a preventer strop that had a single unburied Brummel breaking. It got a lot of press, an official investigative report, and some hard questions were ask of many pro yacht riggers, and Brummel's dropped way out of fashion.

Factually - a Brummel on an eye loop with a long bury after the Brummel is 90-95% strength.  It does distort the weave somewhat so there is some loss.  A simple straight bury (without the Brummel) can be 100% strength.  BUT you then need to lock stitch it, which if you dont do properly (and many people dont know how) you can again easily lose 5-10%.  Commercial heavy lifting (where the testing and quality standards are rather higher than in yachting) pretty much never uses a Brummel because they see no reason to take the small strength loss and they know how to lock stitch properly.

A single Brummel without a bury afterwards, as was done on the Clipper strop, is yes in fact about the strength of a knot - about 50%.  Basically that should never be used when strength is any issue at all.  BUT by using multiple Brummel's you can get that strength back up to around 85% (if you respect the load path) still without having to take the space for a long bury (which may not be available in certain applications).  So, if you understand what you are doing you can use locks with rather greater than knot strength.

And yes, there are good applications for braidback's and they can be full strength in shorter lengths - but some care needs to be taken to ensure all the strands are equally tensioned - if you are at all sloppy it is easy to lose quite a bit of strength.  And they can be a bit more time consuming to do - for big line it can comes down to the cost of extra line length for bury vs the cost of rigger time for the braid, and for big expensive line the riggers time can often be cheaper.

 

 

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@mgs @estarzinger - this prompted me to look back at a few other pics I took and I beleive it was a braidback splice being used in this instance. Got to admit this was 'school day' for me, I wasn't aware of the braidback splice as all my splicing has been done on smaller diameter line where a long bury has been adequate. This is something to try and add to the roster - do either of you have a link for a 'how to' guide that might save me flaying around trying to figure it out myself...?

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49 minutes ago, European Bloke said:

If something else got a linky?

I believe this is what is meant with a (S) lockstitch.

A few questions about this for those that actually know what they're doing.


Is it necessary to rotate ninety degree for full strength or would be stitching in one plane sufficient? I learned the latter years ago and never had a problem. But my ropes are sized for comfort and stretch on a small boat. Unlikely to ever come close to load limits.

When doing the stitch, how critical is it to not stitch through single strands? From what else I read that would distort the weave and should weaken the rope.(again, small boat so it probably doesn't matter all that much for my application but I am curious about the correct method)

Lastly I have been using cut off strands of the dyneema I've been splicing for stitching. Any issued with that beside somewhat more of a pain to undo on account of being hard to distinguish?

 

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@NZKI don’t know of any instructions online. A few months ago Courtland Company had some but everything they have now isn’t it. 
 

I’ve got some real cryptic notes from when I was taught. The start is the hardest part, making sure the braid stays intact as you pull strands and tuck them. 
 

I’m not sure how often you’d really need to know this one. Last sailboat I know that had them was an Open 40 from ‘07, or so, and that’s only because the splicers from Yale Cordage were doing some work on the side.

they are more common in commercial marine operations 

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3 hours ago, allweather said:

I believe this is what is meant with a (S) lockstitch.

 

an alternative pattern - both are fine, more important is they be done carefully https://www.cortlandcompany.com/wp-content/uploads/2020/07/CT_TL_060_0619_US_Cross_Stitching_instructions_lres.pdf

yup.  There are multiple acceptable ways to do the stitching.  The simple key is that it should not distort the braid or put more load on some strands than others. You want to evenly spread it out across a good length of the bury, you want it not too tight (not pulling the braid when lazy) and evenly tensioned (so if/when it does take up it is even across a lot of strands), and you dont want to split strands. In theory using 'thread' with a bit of elasticity (like polyester - nylon is too uv vulnerable to want to use) should help avoid point loading but I have not tested that and it would not make any difference if you stitch well.

This is really a 'feel' thing (rather than a 'technique' thing), best learned either by doing and then breaking many samples and seeing how you do, and/or with a mentor watching commenting over your shoulder. It is easier to do well in really big line - in smaller line you want to use a quite blunt 'needle' so you dont catch filaments or split strands.

4 hours ago, NZK said:

@mgs @estarzinger - this prompted me to look back at a few other pics I took and I beleive it was a braidback splice being used in this instance. Got to admit this was 'school day' for me, I wasn't aware of the braidback splice as all my splicing has been done on smaller diameter line where a long bury has been adequate. 

Like with stitching there and multiple acceptable ways to do this.  The tucking pattern does not matter so much so long as it is clean and neat. Almost any technique with a bunch of tucks will be 100% if you keep the tension even over the strands.  

https://www.cortlandcompany.com/wp-content/uploads/2020/07/CT_TL_064_0421_US_Moran_5-4-3_Tuck_Splice_Instructions_lres.pdf

https://www.samsonrope.com/docs/default-source/splice-instructions/12strand_c2_tuck_bury_eye_splice_hmpe_web.pdf?sfvrsn=c0f746b0_2

http://dynamica-ropes.com/wp-content/uploads/2015/11/Tuck-Splice-Instruction-English.compressed.pdf

There are some techniques, harder than these tuckbacks, where you fully deconstruct and then reconstruct the braid.  I have never successfully made one which tested at full strength but apparently there are very careful people who can.

 

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