Down and Dirty Dyneema Strops

[Dockhead]

Originally Posted by estarzinger

First comment . . . . It will work fine.

Second comment . . . . There are two things that are not "proper"/could be better.

1. Fundamentally the grog sling is a bodge designed to allow you to get away with somewhat shorter buries. But it is not a proper lock, and it weakens the splice. A simple end to end splice (with stitching) with long buries is the proper solution here, if you have room for 60x or more buries. The Brummel is a trap - it looks and feels proper - but it is a weak point and is worse than simple sewing.

2. Really - please make that whipping just a little cleaner I have never looked but somewhere there must be done good instructions/video on how to make a nice proper whipping - anyone have a good link? Make it so that the whipping is slightly angled (a trapezoid - matching the angles leading to the ring) and with nice clean parallel wraps, with the ends pulled cleanly under the whipping . . . . Or (lol) cover it with heat shrink tubing if you can't make it clean.

Now probably those two things will have no practical impact on the device in actual use - it is probably way strong enough as it is - but you will be prouder of it and it will look better be more proper/Bristol.

The other master has spoken

Yes, sir, I'll work on my whipping technique, sir. Yes, I know it's ugly. Now suitably shamed, maybe I'll do those over again.

I'm sorry to hear that this is less strong than a simple long bury. I do in fact have room for a 72x bury (which is what I did here.

Maybe it's back to the drawing board, or maybe it's strong enough -- I'll think about the loads. I don't like the simple bury. My first and second generation ones were like that . They worked fine except that they just fell apart with no load on them. Sewing them would keep them from falling apart, but do they grip in different places every time? It doesn't feel right to me.

[Stumble]

Dockhead,

I do all my dyneema splicing with lock stitches instead of brummels. The trick have found is to sew in the stitches just after making the bury, before tapering and the final bury of the tail. Basically you get the stitch where you want it without ever letting the line slide back over itself. Once the first stitch is in its generally secure enough for a light smooth down of the area.

Remember the lock stitches are not there to carry actual load, just to stop the legs from sliding against each other until the finger trap mechanism can take over. So they don't need to be perfect, and should be made with as small a piece of whipping line as possible. The smaller it is the less distortion in the finished splice.

[Cruisingscotts]

If you are not worried about sacrificing a little ROPE, you can bring your tails out of the core where the taper will end, without tapering the ends plus a few inches. You start your lock stitching at the center point of of the buries and stitch down to where the taper will start then complete the stitches back to the center point and down the the other way and back finishing with a siezing at the center point. You can then pull the tails from the core to the bottom of the stitching and taper and milk back into the core. I usually go a little loose on the first run down of stitching milking it as I go then a tighter finishing stitch on the way back to the center. One advantage to a slightly shorter bury is you can use the opposing end for your ring with a brummel to lock in place. It's nice to be able to remove or change without having to cut a siezing.

What brand of ring are you using? I picked up a harken one the other day as they were out of antal and the finish does not seem to be as good. The antal ones seem to take some abuse and stay nice and smooth not sure how the harken one will hold up.

[Seaworthy Lass]

Originally Posted by Cruisingscotts

If you are not worried about sacrificing a little ROPE, you can bring your tails out of the core where the taper will end, without tapering the ends plus a few inches. You start your lock stitching at the center point of of the buries and stitch down to where the taper will start then complete the stitches back to the center point and down the the other way and back finishing with a siezing at the center point. You can then pull the tails from the core to the bottom of the stitching and taper and milk back into the core. I usually go a little loose on the first run down of stitching milking it as I go then a tighter finishing stitch on the way back to the center.

Hi Cruisingscotts
A simple constrictor knot tied at the junction when both ends have been buried and the junction is snug, will hold the buries neatly in place. You can then taper, milk and lock stitch without any tendency for the ends to slide out of place. The constrictor can then just be snipped off.


SWL

[TheOffice]

I suck at splicing, so I am asking out of ignorance - not to direct you how to do it.
Where you have the ring, why not run one leg of the line through the other to pull it tight instead of relying on the whipping? (or did I just miss that you did it?)

[Seaworthy Lass]

Originally Posted by TheOffice

I suck at splicing, so I am asking out of ignorance - not to direct you how to do it.
Where you have the ring, why not run one leg of the line through the other to pull it tight instead of relying on the whipping? (or did I just miss that you did it?)

When load is applied the legs want to straighten and therefore separate. Bringing the legs together tightly as this point strains the fibres unnaturally and this will weaken the loop, so it is not ideal.

SWL

[Cruisingscotts]

Very true on the constictor knot, for the fat fingered it can get a little tedious on the small stuff though.. I found the extra tails helpful starting out and abondoned as I get better and cheeper.

Do you know if there has been load testing on brummels vs. siezings? Have used both and the untested rely on the untested theory they are about the same amount of sacrifice for the same radius. The seizing loading the outside fibers more and the tucked through the core arrangment loading the weave but due to opposing exits more even on the fibers as a whole.
Sort of off topic but on the commercial fishing vessel I work on they have been using dynema and spectra since it came out. I don't think I have ever heard of a splice related failure. Lots to do with chaffe and lots at the loading point over a shive.

[Cruisingscotts]

very cool page

Load testing

[estarzinger]

Originally Posted by Dockhead

Yes, sir, I'll work on my whipping technique, sir.

Excellent . . . . Wax on, wax off my son
It may not have been clear because of my sarcasm font, but the heat shrink tubing was not an idle suggestion. Without any whipping under it, it is almost a perfect solution for this application. . . . Will hold the ring in place while stretching enough to place no odd load on the dyneema and a pretty fast and clean. Cheap tubing is uv sensitive (gets brittle) but there is higher grade that is quite uv resistant . . . And you can just slice off and replace periodically. Also you can double layer so inside layer is uv protected.
Correct whipping is more proper and prettier and SL will like better . . . But tubing is quite functional

Maybe it's back to the drawing board, or maybe it's strong enough -- I'll think about the loads.

Oh, they are "strong enough". Something else will break first before those strops! It is something I gained great appreciation for while breaking a lot of this stuff - you will bend decent size high tensile bolts and deform high tensile rings before breaking this stuff. Chafe/cutting and uv and bend radius will be the likely cause of any practical breakages.

samson has a nice video showing how to stitch the splice in a clean fashion that does not produce any unnecessary stresses on the rope. They show doing it on like 2" commercial rope where it is actually a bit easier to do . . . But the basic intent is simply to add some "connective fibers" so the two parts can not slide apart at low load while not stressing anything at high load. It is more "splicing" than sewing . . . You want to use a fid or very blunt needle so you go between strands (in the 12 strand lay) rather than thru strands. And it should be loose-ish rather than pulled tight. Work "with the rope" rather than violating it. A 72x bury has a lot of natural friction and does not need all that much help to be absolutely solid at low load slipping.

One interesting technique that is used in the "commercial heavy lifting" business - where their (big) sizes can cost +$100/m is a tuck splice (as is done with plait). This can be much shorter and saves them the material cost of the 72x buries. I have also seen much shorter buries used, with the strands at the ends of the buries/tapers then each tucked a couple times - but this is easier done in big sizes.

...........

[Cruisingscotts]

One interesting technique that is used in the "commercial heavy lifting" business - where their (big) sizes can cost +$100/m is a tuck splice (as is done with plait). This can be much shorter and saves them the material cost of the 72x buries. I have also seen much shorter buries used, with the strands at the ends of the buries/tapers then each tucked a couple times - but this is easier done in big sizes.


Thats how I was taught in the late 90's. A small swedish fid and it's OCD heaven. Looking in a samson book there process is a little different. Was taught to bring half the strands thu the core and run pairs up a plait with alternating tucks, tapering the terminations. Makes a nice short tight splice, but have never seen a load test comparision of a buried splice.

[Seaworthy Lass]

I have spent some time this evening hunting for instructions on trapezoid whipping. Nothing was found, but it did lead me on a few tangents.

I have found Sailing Anarchy has some info on strops for low friction rings.
Eg: dyneema loop with low friction ring construction - Gear Anarchy - Sailing Anarchy Forums

I needed to join SA to view the photos .

Interestingly, the method of burying a short length of dyneema around the ring to restrain it was shown. The bury is just longer than I used (in Dockheads other thread on strops). Evans called it "constrictor style", so it is not a new thought.

A search shows that the long thread there on load testing contains info on strops as well. That thread may contain some useful gems.

Anyway, back to the issue of trapezoid whipping on strops. Anyone know of any instructions online? I am not sure what stops the loops of the wider turns near the ring sliding down in time if thin whipping line is used.

SWL

[Seaworthy Lass]

Originally Posted by estarzinger

..........samson has a nice video showing how to stitch the splice in a clean fashion that does not produce any unnecessary stresses on the rope. They show doing it on like 2" commercial rope where it is actually a bit easier to do . . . But the basic intent is simply to add some "connective fibers" so the two parts can not slide apart at low load while not stressing anything at high load. It is more "splicing" than sewing . . . You want to use a fid or very blunt needle so you go between strands (in the 12 strand lay) rather than thru strands. And it should be loose-ish rather than pulled tight. Work "with the rope" rather than violating it. A 72x bury has a lot of natural friction and does not need all that much help to be absolutely solid at low load slipping.
.

That is very interesting info and "violates" is a good term. One of the main reasons I dislike the thought of stitching dyneema to lock it is that it "violates" it. I take great care not to split strands when making soft shackles or splices or to create stress points, and sewing through it just goes so against that principle.

The only problem is that I can see how you could sew between strands for the outer core of the buried portion, but how could you achieve this for the inner bit? I find I need to push the dyneema together to find an easy path and I rely on vision as well as feel to do this. I can't see how this could be done well for the buried portion. Or is it that not "violating" the outer portion that can be milked is more important than what happens to the inner bit?

SWL

[Cruisingscotts]

Originally Posted by Seaworthy Lass

Anyway, back to the issue of trapezoid whipping on strops. Anyone know of any instructions online? I am not sure what stops the loops of the wider turns near the ring sliding down in time if thin whipping line is used.

SWL

I would think a benzel (sp) would accomplish what you are after. Probably a correcter term like linezel or ropezel out there. Rather than siezing the two parts tight and finishing with perpendicular stitching, the wraps are applied loose and the center is finished with the perpendicular wraps tucked alternately leaving a gap between the lines and the ability to flex. This is sort of how traditional standing rigging is siezed in loue of splicing. In that case multiple siezings must be done but on a strop both sides would be equally loaded on either side so probably only one would be nessessary, but it could be followed by a reagular siezing a little farther down.

[Seaworthy Lass]

Originally Posted by Cruisingscotts

I would think a benzel (sp) would accomplish what you are after. Probably a correcter term like linezel or ropezel out there. Rather than siezing the two parts tight and finishing with perpendicular stitching, the wraps are applied loose and the center is finished with the perpendicular wraps tucked alternately leaving a gap between the lines and the ability to flex. This is sort of how traditional standing rigging is siezed in loue of splicing. In that case multiple siezings must be done but on a strop both sides would be equally loaded on either side so probably only one would be nessessary, but it could be followed by a reagular siezing a little farther down.

Any photos?

I had a go loosely seizing a low tension ring in a double dyneema loop a few weeks ago. It was functional, but clunky:



What I would love to learn to do is trapezoid whipping similar to the gorgeous work by an Italian gentlemen. Evans posted this photo on Dockhead's other thread:

[Cruisingscotts]

Thats the idea, only with smaller siezing line, oops rope, and not as long. I have a couple with me that I am using as a pattern to make leather chaffe guards. I'll take some pics tonight when I get off shift. I can get away with forum browsing, but breaking out the ditty bag would kinda be pushing it.

The finish work in the above photo is pretty crazy, obviously done by one of those people you woudl have to use a vernier caliper on to measure the variance in their stitch lengths.