GHA
Well-known member
1000%!!!!!!!!!!!!! ?
Dynemma eye splice brummel lock
- Thread starter Gsailor
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thinwater
Well-known member
I think one question that was not answer is the strength of the stitching or Brummel.
Brummel only. About 30-40% of line strength. A multi-Brummel, with 6 or more tucks, gets close to splice strength ... but it's messy so no one does.
Stitching only. About 50% of the of the breaking strengths of the passes. For example, 20 passes of 100# test twine = 1000 pounds. This is closer to 100% in polyester (more friction). There are reasons for sewn splices in polyester and nylon rope (old rope is very hard to splice, some weaves don't splice well, geometry can be better, it is much faster, and it is easier to get the length right), and I have tested hundreds and used many, but not in Dyneema, because Dyneema single braid does not hold thread very well, it frays terribly, and it splices piss-easy, even old.
This is not to suggest skipping the bury is a good idea. Quite the opposite. There was a fatality on a Clipper RTW boat in part caused by the failure of an eye that was Brummel-only. The 72:1 rule is based on an effective lock PLUS a bury.
Brummel only. About 30-40% of line strength. A multi-Brummel, with 6 or more tucks, gets close to splice strength ... but it's messy so no one does.
Stitching only. About 50% of the of the breaking strengths of the passes. For example, 20 passes of 100# test twine = 1000 pounds. This is closer to 100% in polyester (more friction). There are reasons for sewn splices in polyester and nylon rope (old rope is very hard to splice, some weaves don't splice well, geometry can be better, it is much faster, and it is easier to get the length right), and I have tested hundreds and used many, but not in Dyneema, because Dyneema single braid does not hold thread very well, it frays terribly, and it splices piss-easy, even old.
This is not to suggest skipping the bury is a good idea. Quite the opposite. There was a fatality on a Clipper RTW boat in part caused by the failure of an eye that was Brummel-only. The 72:1 rule is based on an effective lock PLUS a bury.
thinwater
Well-known member
The only use I have for non-Dyneema shackles (technically they are knotted strops) is sail ties and loops for hanging lines, and if you can't tell the difference between polyester cover and 12-strand Dyneema you're dumber than a bag of hammers.
The reasons are that polyester cover is easier to handle wet than Dyneema and that larger diameters are easier to handle. Same reason we don't use naked Dyneema line tails. Money has nothing to do with it.
Some of my soft shackles are toggled rather than knotted because I find them easier to handle in rough conditions. Again, nothing to do with money or difficulty in making either. They just work better for some things.
The reasons are that polyester cover is easier to handle wet than Dyneema and that larger diameters are easier to handle. Same reason we don't use naked Dyneema line tails. Money has nothing to do with it.
Some of my soft shackles are toggled rather than knotted because I find them easier to handle in rough conditions. Again, nothing to do with money or difficulty in making either. They just work better for some things.
lustyd
Well-known member
Haha the only one I have was made out of lazyjack rope. It's very cheap at £1/m vs £6.40/m but less strong 1100KG vs 4300KG. It's virtualy indistinguishable from Dyneema of the same silver colour and when I finished I thought exactly this, it's dangerous to have non-dyneema ones. I didn't want or need a soft shackle, I just wanted to try making one, but then I binned it!
lustyd
Well-known member
Far more importantly, it's based on a tapered bury. If you don't taper properly you may just as well tie a knot. Hownot2 showed this very nicely on YouTube, and the rope broke at the end of the bury without a taper at well below MBS.
thinwater
Well-known member
If we're going to get into technical stuff, let's not exaggerate.
A knot in Dyneema typically fails or slips at 25-35% MBS, depending.
Skipping the taper weakens the splice about 15%. It will break at the end of the bury. For example, a whoopee sling (no taper--the tail comes out through the braid) is about 15% weaker, per Samson.
GHA
Well-known member
Gsailor
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I posted about the brummel lock eye and it is only since I received replies here and in another post that I have discovered people appear to be talking at cross purposes.
A brummel lock eye splice seems fine (thinwater states up to 45 % stength without stitching).
People jumped in and talked about stitching as if I had only mentioned an eye splice instead of of a brummel lock eye splice.
Am I correct?
Thinwater states stitching a brummel LOCK adds 5% strength.
For my needs it seems a brummel lock will not come loose 95% of the time.
The video in my post no. 1 seems to look rock solid.
I think I understand that stitching is 'mainly' for eye splices without the brummel lock.
A brummel lock eye splice seems fine (thinwater states up to 45 % stength without stitching).
People jumped in and talked about stitching as if I had only mentioned an eye splice instead of of a brummel lock eye splice.
Am I correct?
Thinwater states stitching a brummel LOCK adds 5% strength.
For my needs it seems a brummel lock will not come loose 95% of the time.
The video in my post no. 1 seems to look rock solid.
I think I understand that stitching is 'mainly' for eye splices without the brummel lock.
Gsailor
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My device won't access that page for some reason..
Neeves
Well-known member
Neeves
Well-known member
You added to the confusion by suggesting would we, I, bet my life on your work - with a 5% failure rate (for someone who has a few splices under their belt( - No. It might be fine for the application you were actually thinking of - but not for securing an individual.
Jonathan
Gsailor
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Fair enough, but my confusion started after post 1 where I posted a link to a brummel locked splice :
" As in this video:
dyneema eye splice - Google Search
Is this eye 100% secure from slippage? It looks good to me.
I have been told to stitch the bury or stitch near the eye but is that necessary?"
This was followed up by talk of stitching.
STILL confused, but as far as I can deduce a LOCKED brummel eye splice is pretty secure without stitching? That was my original question. I would never under any circumstances (stitching or not) simply make an eye and bury 70% of the diameter and think it good enough.
So back to post one: is a brummel lock eye splice secure? The locking as per the video seems irrefutable.
I have a hydraulic press, perhaps I should test to destruction a brummel LOCK splice?
Neeves
Well-known member
You could test to destruction - it would be an interesting piece of data. The question is do you know the tension under which your proposed splice is to be used? If you don't know then the data on testing your splice would be academically interesting but not applicable. Why not tell us what you propose to make, size (diameter), and the application.
You have enjoyed some thread drift (its a forum) - it may or may not have been relevant - only you will know. Often thread drift raises new question the OP never thought they needed to know (or not).
Jonathan
For a device to secure an individual I'd expect a decent safety margin - 95% would be factorially too low. I actually suspect individual safety is not, was not, part of your perameters - except that you raised it. For example - when doing mast work we all use a halyard whose strength is immeasurably stronger than the likely load - and we then use a back up as a safety line - real belt and braces (and I've actually never heard of the primary halyard breaking (but I'm sure it has happened). 95% is a long way from 2 halyards. Anchor chain is usually well over strength, over specified, but has a 4:1 safety factor and is proof tested (that's 2 x WLL) continuously during manufacture. I have not heard of an anchor chain failure through a link breaking for at least 10 years - and anchor chain is not considered in terms of an individual's safety. Anchor shackles have a safety factor of 5:1 or 6:1. A failure of 5 out of every 100 applications is not quite as bad as Russian roulette but - I would not want to be the 96th person. Bomber crews in WWII had a life expectancy of 20 sorties - beyond which they were on borrowed time. Maybe acceptable in times of war - 95% is similar.
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Gsailor
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Bit late for me, but I was mesmerized that a brummel lock and simply burying the bitter end end seemed to provide a secure eye. WOW dyneema.
The thread then went on to stitching but a different thread about stitching said "why not use a brumnel lock?" Which made me do a double take.
I have no use or product in mind; I know dyneema is extremely strong.
I perhaps wondered if a BRUMNEL lock eye splice with no stitching was strong enough to support a 13 stone person assending a mast.
I would always prefer to lower a mast.
Just theoretically talking.
Some how the "brummel lock" in the title seems to have been overlooked perhaps?
Hence my confusion.
The thread then went on to stitching but a different thread about stitching said "why not use a brumnel lock?" Which made me do a double take.
I have no use or product in mind; I know dyneema is extremely strong.
I perhaps wondered if a BRUMNEL lock eye splice with no stitching was strong enough to support a 13 stone person assending a mast.
I would always prefer to lower a mast.
Just theoretically talking.
Some how the "brummel lock" in the title seems to have been overlooked perhaps?
Hence my confusion.
Neeves
Well-known member
Some masts are that little bit heavy to lower and thus cost real money to use a crane (especially if they are keel stepped). I'm more than happy up a mast. Its an expensive exercise if you need to drop a mast to change a masthead light, which is one reason we have both masthead and deck located nav lights.
Its not the 13 stone man (what on earth is a stone ??
) its the 13 stone man falling a bit before tension is placed on the device. If you were to test - you need to try to simulate the environment in which the device is used - so not the weight of the 13 stone man but that same weight falling say 1m and using the same or similar attachments, carabiners, knots etc etc. If it were 'just' to test a bury you need to jiggle it around a bit (as it might be in use) to loosen it up etc.
Ask Thinwater - he has done it all, or most of it.
Jonathan
thinwater
Well-known member
You took that out of context. It actually subtracts strength from an eye splice. Not much, but some. Towing lines, for example, are not Brummel locked, they are lock stitched.
- An eye splice that is Brummel-only is about 45% BS. You can get more strength with a multi-Brummel.
- An eye splice that is Brummel + bury is about 90% BS.
- An eye splice that is standard lock stitch is 20-30% BS. Can be much stronger if more stitching is added, but it is not needed with a bury. If it were to be stitch-only, you would stitch a lot more and it would be similar to a multi-Brummel (~ 80-85% BS).
- An eye splice with standard lock stitch + bury is about 95% BS.
So a Brummel is not better, it is different, with different pluses and minuses. I use either, depending on the situation.
thinwater
Well-known member
This is correct. You do not do a Brummel and stitching. It is one of the other, not both. I doubt they play well together.
William_H
Well-known member
Wouldn't like to argue on strength of Bumell splice with buried tail. I did use 5mm dyneema to make up a new back stay fro the little boat. No problems with the first eye and I manged to get the first eye on the end of the rope through the opened braid to complete the second brumell eye splice. All seems good in service. I have also replaced srteel wire on trailer winch with same 5mm dyneema and eye splices. That might be an even sterner test but won't be until haul out next April. Will let you know if it fails. ol'will
lustyd
Well-known member
thinwater
Well-known member
Funny that many of the videos and instructions show a too-short bury. I'm sure the guys know this. Also, they often say "x fid lengths," but the length of a fid can vary. Somewhere in the fine print they explain a fid is 21 rope diameters. Finally, some do not distinguish between class 1 and class 2 (polyester vs. Dyneema, which is rather important.