Down and Dirty Dyneema Strops

[Dockhead]

[EDIT: THE WHIPPING SHOWN BELOW DOES NOT WORK. SEE SEVERAL ALTERNATIVES WAYS OF CAPTURING THE RING DEVELOPED IN THE THREAD BELOW.]


Ropework is not one of my -- ahem -- several talents. I don't know why, but I don't have the right kind of imagination for it. I like ropes, but alas -- they don't seem to like me. I have difficulty following the various types of instructions, especially the videos which are now so popular.

However, splicing muss sein, and lots of it. We changed back to my blade jib from the yankee in anticipation of a 1000 miles of bashing upwind, and I needed to put together at last the final dyneema strops with low friction eyes which I use for sheet leads. Besides that, tons of other uses for these have appeared, such as turning blocks, snatch blocks for barber haulers, etc., etc. I need about 8 of them.

I struggled with different ways of doing them. The last batch had brummel eyes at either end, both put around the low friction ring, then seized in place. I had initially thought, foolishly, that I could make the eyes tight around the low friction ring -- hah. But a little seizing solved that.

That seemed like a decent solution, but I spend a day on a Swan 60 racer with dozens of these all over (and not a conventional block in sight), which were simple spliced loops with a velcro seizing -- nice. And I realized that a simple spliced loop would probably be stronger and more elegant, and that retaining the ring is not really the biggest problem.

So I struggled through different instructions on making spliced loops, and finally hit upon one which made sense to me, here: Grog Sling | How to tie the Grog Sling | Splicing Knots

As usual the instructions were as clear as mud, so I decided that maybe I could help other sailors who lack the ropework gene by explaining in a more straightforward way how to do it.

So here's how I'm now doing it, and it takes less than 10 minutes per strop.

1. Gather your tools. I am now using the expensive but worth it D-Splicer and the special dyneema scissors from them (even more expensive and even more worth it). This is not necessary. You can use a really sharp knife and a piece of monel seizing wire instead, and this works almost as well. But the D-Splicer tools are a real pleasure which many will find worthwhile.

So -- splicer (or monel wire), scissors (or sharp knife). Then: Ball point pen, ruler, sail needles, waxed whipping twine, the raw material (I'm using 6mm 12 strand single braid).


2. Measure off 1.65 meters of your single braid and cut it off.

3. Middle it, and mark the mid-point with the ball point pen.

4. Middle it again, and mark the two quarter-points with the ball point pen.

5. Make two marks down-rope from the two quarter points, about an inch down. This is where you'll do the brummel thread-throughs.

6. Take your ball point pen, scrunch the rope together a bit at one of the thread-through points, then gently stick the pen through and expand the rope around it to open up an eye. Let's call that leg "A".

7. Thread the other leg, "B", through the eye you just made in "A".

8. Now make a similar eye at the thread-through point in leg "B", and thread the end of leg "A" through it, and snug these two points together.

9. Now, take your splicing tool (or monel wire), and stick it into the rope at the mid point. Scrunch the rope up to expand and open it up, then gently thread the splicing tool down through the hollow center until you reach the interlocked brummel eyes. Let the splicing tool come out just opposite the leg which is obvious for threading through that leg, and a couple of strands away from the interlocked brummel eyes.

10. Then grab the end of that leg in your splicing tool, and gently thread it through, expanding the outer part so that the inner part can go through easily. In practice, it's just a little tricky to get the end inside, after which it goes right through. Pull the inner part all the way out, scrunching up and pulling back the outer part as much as possible to get it out of the way.

11. Now taper the inner part. Snip alternate left and right strands at even intervals.

12. Now "milk" the outer part down over the inner part.

13. Repeat with the other side and you're doing with the loop.

14. Now put your low friction ring in place. I am putting it right where the interlocked brummel eyes make a bump.

15. Take a piece of whipping twine and thread your sail needle with it. Stick it through both legs of the rope, wrap the two ends in opposite directions and tie them down with a reef knot.

16. Cut the thread at the middle where the needle is, and wrap both ends in opposite directions. Tie them off with a reef knot, and trim the loose ends.

15. Secure the ring using one of the methods developed in the thread below.

Done!


1.65 meters of 6mm dyneema yields a 450mm long strop -- a handy length.

This is a full 72x long bury which should be nearly the full strength of the rope.

It's not very pretty (I am in awe of those talented rope-workers on here like Seaworthy Lass who are able to make these into works of art, but that is beyond my meagre talents), but strong and good.

It's possible that there are some mistakes in the technique, which is partially derived from different instructions, and partially intuited (dangerous coming from me), so I will be grateful if any more knowledgeable person will point out any flaws.

[Seaworthy Lass]

I'll run through your instructions and see how I go.

I find written instructions hard to follow for knots though. Seriously, pictures on their own do it for me, I sometimes get totally bamboozled by written directions .

SWL

[Seaworthy Lass]

Just one comment before I follow your procedure:

The Grog sling is not a standard spliced loop. In a Grog sling at the Brummel lock the ends are flipped back 180°. I think this would weaken the loop at this point. It is a super quick way to lock the splice though and, as I understand it, close to max strength for a Grog sling is achieved with a 30x bury, so a shorter strop can be made if needed. As absolute max strength is generally not needed with these strops (the Dyneema strength is generally overkill), I personally like this sling (as opposed to a standard spliced loop).

In a standard spliced loop, one end is simply fed into the other (in other words rather than creating holes all the way through at A and B, the ends as simply fed in at these points. If tension is going to be released and applied, the ends would eventually slide out, so they need to be sewn down (ie 2 long lines of zig zig stitching).

SWL

[Cruisingscotts]

Ahhh. Line! not Rope,


Nice "line" strop. haha


Useful tool, small Swedish fid instead of a pen, also handy for tucked splices


I would look into Lock stitching. You should verify the current recommended procedure from the manufacture, but for the most part I'm pretty sure the locking tuck is not necessary as long as you have multiple lock stiches running though the buried core.


Made a bunch of these, one neat note. If you OCD on the length and use a large diameter ring with smaller diam dynema and multiple wraps on the ring you can get them to stand up on a eye. Nice for sheet leads. Next size up from the ring you have pic'd and about the same size line. Feed the strop through itself on the attachment eye then alternating wraps around the od of the eye, helps if you pre-load the strop to set it.

[Seaworthy Lass]

OK, I have followed your steps and the only point of confusion for me was in your Step 7.

There is one little bit I think needs to be added to make the correct instructions clearer:

Thread the other leg, "B", through the eye you just made in "A" until the biro mark has been pulled through.

If you don't do this, you will not have a Brummel lock, nor will the working ends then bend 180° before being threaded through with the splicing tool. This is a hallmark of the Grog Sling. Just make sure the configuration looks like Grog's image 8 before proceeding past your Step 7.

Regarding your whipping at the end, I am not overly comfortable with that, but it may be perfectly serviceable. There will be a fair bit of force pulling the legs of the strop apart at this point and whipping twine is thin and sharp. I would be happier using 2-3mm double braid, securing it very loosely closer to the ring, creating less stress on the dyneema when under load. Velcro would do the same thing.

EStarzinger will be able to give you better info about this. I just have truckloads of enthusiasm rather than expertise .

SWL

[Dockhead]

Originally Posted by Seaworthy Lass

OK, I have followed your steps and the only point of confusion for me was in your Step 7.

There is one little bit I think needs to be added to make the correct instructions clearer:

Thread the other leg, "B", through the eye you just made in "A" until the biro mark has been pulled through.

If you don't do this, you will not have a Brummel lock, nor will the working ends then bend 180° before being threaded through with the splicing tool. This is a hallmark of the Grog Sling. Just make sure the configuration looks like Grog's image 8 before proceeding past your Step 7.

Regarding your whipping at the end, I am not overly comfortable with that, but it may be perfectly serviceable. There will be a fair bit of force pulling the legs of the strop apart at this point and whipping twine is thin and sharp. I would be happier using 2-3mm double braid, securing it very loosely closer to the ring, creating less stress on the dyneema when under load. Velcro would do the same thing.

EStarzinger will be able to give you better info about this. I just have truckloads of enthusiasm rather than expertise .

SWL

Thanks! The master has spoken!

A couple of questions and comments:

1. So you mean that my 72x bury is not doing anything? That's a shame -- I had hoped to be getting full strength.

I did make one of these as a simple spliced loop but it falls apart. I don't mind sewing it, but I just didn't like that aspect of it. It seems failure-prone even with stitching. I prefer the brummel splices which seem to weld into an inseparable mass.


2. I'm pretty sure I have the brummel lock right. That bit does look just like in the Grog photos. Thanks for clarifying my instructions.


3. Concerning the seizing -- this is a very shallow angle so, I would have thought, very little stress. But I guess I'll see how it works in practice. So far so good, and I'm using them under multiple tonnes of stress in my sheet leads, as I type this in fact


Thanks again!

[StuM]

Originally Posted by Cruisingscotts

Ahhh. Line! not Rope,


Nice "line" strop. haha

.

I beg to differ.

It's rope until it's put to use.

The strop is made from rope. So it's a rope strop.

[StuM]

Originally Posted by Dockhead

1. So you mean that my 72x bury is not doing anything? That's a shame -- I had hoped to be getting full strength.

Depends on what you mean by "full strength". The breaking strain of that strop should be better than the breaking strain of the dyneema itself. Even if the strength of the join is only 50% the load on each leg is only half the total load.

[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.

[Seaworthy Lass]

Originally Posted by Dockhead

A couple of questions and comments:

1. So you mean that my 72x bury is not doing anything? That's a shame -- I had hoped to be getting full strength.

EStarzinger has tested the Grog Sling. As I understand it, only a minumum 30x bury is needed, not 72x for this type of loop. I guess that with the 180° bending of the dyneema, the break point is here and the loop will break at lower loads than a standard spliced loop. Evans will be able to elaborate on this.

Originally Posted by Dockhead

I did make one of these as a simple spliced loop but it falls apart. I don't mind sewing it, but I just didn't like that aspect of it. It seems failure-prone even with stitching. I prefer the brummel splices which seem to weld into an inseparable mass.

Under load I doubt very much it would fall apart. If a constant load is kept on the end to end splice is needs absolutely no lock or stitching for it to hold.

I know it is hard to believe when the loop parts so easily when it is gently tugged with a bit of wriggling. Being a little sceptical, I wanted to try it out under load so I tied an unlocked loop in dyneema with 72x line diamter bury of the ends simply threaded in. I tried winching it with all the force I could exert, expecting it to slide apart in an instant. It was just amazing how the outer portion gripped the core with constant force applied . I couldn't get it to budge even the slightest.

A couple of lines of zig zag locking stitches are just needed to stop the ends sliding out while the load is off. I would want to make those in UV resistant thread though.

Having said all that, I do like the lock in the Grog Sling and the ease of making it.

Originally Posted by Dockhead

2. I'm pretty sure I have the brummel lock right. That bit does look just like in the Grog photos. Thanks for clarifying my instructions.

The Grog sling should have a substantially thickened bit at the lock because it doubles back on itself, not be smooth as the lock is in an eye splice. This bit was hidden by your low tension ring and the lack of mention of the 180° bending of each standing end made me wonder if you had done this.

Originally Posted by Dockhead

3. Concerning the seizing -- this is a very shallow angle so, I would have thought, very little stress. But I guess I'll see how it works in practice. So far so good, and I'm using them under multiple tonnes of stress in my sheet leads, as I type this in fact
Thanks again!

You're welcome
I am learning lots in the process too. I enjoy knots and splices .

SWL

[Seaworthy Lass]

I see Evans has replied. I was slow typing .

[Dockhead]

Originally Posted by Cruisingscotts

Ahhh. Line! not Rope,


Nice "line" strop. haha . . .

I struggled for a long time with my inner pedant, trying not to comment on this, but as usual, I failed. Sorry!

Rope is the material; it's one type of cordage (besides cable, small stuff, etc.). A line is rope or other cordage put into use for a specific purpose. Dock line, reefing line, etc., made out of rope. I keep a coil of 16mm poly rope on my pushpit. If I use it to make a long spring line, it's a spring line when it's being used; if I use it as a shore tie, it's a shore tie. But coiled on my pushpit waiting for its next assignment, it's a coil of rope or just "a rope" or "that rope over there."

Don't say "300 feet of line" or a "coil of line" -- it sounds lubberly. Rope -- when it's the material without a specific function. Unless of course it's cable or small stuff. "Ropework", not "linework".

[/pedant mode]

Sorry for the lecture -- can't help myself sometimes. This particular thing ("there's no rope on a boat") is one of my pet peeves.

[Dockhead]

Originally Posted by Seaworthy Lass

. . .I enjoy knots and splices .

Don't I know it. It makes one wonder.

[AD28]

No comment on the technique, but I find these tools to be useful:

Brion Toss Yacht Riggers, Sailboat Rigging::Splicing Gear

The shears are also available elsewhere, they're by Vampire Tools, known as 'kevlar shears.' Google that, might get you best prices, f.ex: https://www.amazon.com/8-Fiber-Optic.../dp/B00FE3IROE

[Seaworthy Lass]

Originally Posted by Dockhead

Don't I know it. It makes one wonder.

I initially wrote "I enjoy ropework", but I didn't want to set any imaginations running wild, so I scrubbed it .