Splicing Advice -- Dyneema

[Dockhead]

Here's something about it:

Low friction ring and dyneema loop - SailNet Community

According to this, it's just a spliced loop with whipping. Easier to do than what I've been doing. Cool.

[Dockhead]

By the way, great thanks are due from the whole community to Evans for this great work on knots and splices:

Load testing

A key reference!

[transmitterdan]

Originally Posted by Dockhead

That looks great!!

I don't need anywhere maximum strength for my application, but still -- what is in your picture is actually what I wanted in the first place. How is it done? How is the ring "cleverly captured"? Maybe I'll do the rest of them like that.

Dockhead,

It appears to be a end to end splice. This is same as an eye splice except you bury both ends to form a complete circle.

It also appears that they use shrink tubing over a whipping. Can't really tell for sure. If it is shrink wrap be very careful. Dyneema does not like temperatures much above the temp at which the shrink tubing shrinks. One trick is to shrink the tubing by immersing in gently boiling (not rolling boil) hot water. This helps insure a tight shrink without over stressing the Dyneema strands.

[estarzinger]

Originally Posted by Seaworthy Lass

Evans, I have a query about the Brummel. Is the twist in the holes detrimental? Some methods leave the twist in, others work to kink it out, and the method of using both ends to work with avoids it altogether. What is best?

Also in some methods the working end goes through the standing part first and in others vice versa. Is one preferable?

First, all the best testing has indicated that the splice without Brummel is on average a bit stronger than with Brummel - this is statistically measurable. New England Ropes looked into this extensively when we were looking at lifelines, and recommends without Brummel (but of course then you do need to sew it so it does not slip under low load cycling).

Second, if doing a brummel you want to disturb and twist the fibers as little as possible, but the difference between a twisted and untwisted one is in fact not easy to see in tests with statistical significance. The best brummel method is to use both ends, but if you are going to splice a loop to each end you can usually only do that method at one end.

Third, you want the Brummel passes to be close to each other, and properly done it does not matter which is first. But it will be measurably weakened if they are some distance from each other. This was counter-intuitive to me at first (I thought it should make no difference) but longer distance allow uneven stresses to develop on the pass thru's.

Originally Posted by Dockhead

That looks great!!

I don't need anywhere maximum strength for my application, but still -- what is in your picture is actually what I wanted in the first place. How is it done? How is the ring "cleverly captured"? Maybe I'll do the rest of them like that.

First, the 'tight eye' geometry (like the design you have been making) will reduce the strength by 15-20%. Which is also about how much crunched/tight tapers can reduce strength. Usually this is not a problem because the dyneema is so strong and the aluminum low friction rings actually have relatively low working loads (compared to the dyneema).

Second, just FYI, the very very easiest way to do this, is to splice an end to end loop right thru the middle of the low friction ring (rather than around the outside). That way you don't have to do anything at all 'clever' to capture the ring - you just have a closed loop thru the ring, which cannot ever slip off. This does reduce the bend radius, but the important part is that it is still a big enough radius to be 100% full strength.

Third, there are four ways to 'cleverly capture' the ring. (1) when you make an end for end splice you will note that you create a closed hole in the line (where the end for end splice comes together). So the first way is just to put the ring in that hole and tighten it up. (2) you put a double loop around the ring, and you put a pass thru on the first loop (half a brummel) at the top of the ring (180 degrees from the other end) which slip nooses the ring and then the sewing or sleeve you see in the picture just keep the second loop from slipping off. (3) You add/splice in a small piece of cordage 'under' the ring to hold it. (4) you do some beautiful sewing (really just a pretty extension of #3, adding some light line to capture the ring) . . . .see this picture from an Italian friend who (I think) makes the nicest looking rope work in the world.

images.jpg Views: 294 Size: 179.7 KB ID: 102524" style="margin: 2px" />

These are all full strength if done correctly. I believe #2 is the vendee/volvo best practice. #4 is perhaps mechanically the best but takes too much labor for the pros to want to do.

I might note that in the first photo I posted above, which is from the Antal website, you can tell just by looking that the tapers are too short . . . . . if you want the strop to be short . . . . too short to make properly long tapers, then the correct thing is to make a 2x longer loop (which gives you more room for the tapers) and double it over . . . . . . .or an 6x lashing. If you go down this road you just have to make sure the design can equalize tension between the various strands.

[fallingeggs]

Evans, that second recommendation is really interesting and pretty simple. Thanks for sharing.

Is there a preferred type of whipping thread to use for these applications?


Sent from my iPhone using Cruisers Sailing Forum

[Seaworthy Lass]

Originally Posted by estarzinger

Second, if doing a brummel you want to disturb and twist the fibers as little as possible, but the difference between a twisted and untwisted one is in fact not easy to see in tests with statistical significance. The best brummel method is to use both ends, but if you are going to splice a loop to each end you can usually only do that method at one end.

Third, you want the Brummel passes to be close to each other, and properly done it does not matter which is first. But it will be measurably weakened if they are some distance from each other. This was counter-intuitive to me at first (I thought it should make no difference) but longer distance allow uneven stresses to develop on the pass thru's.

Great info. Many thanks. I have not found this despite lengthy searching.
Would you suggest not leaving two holes between insertions then?

Originally Posted by estarzinger

.... you do some beautiful sewing (really just a pretty extension of #3, adding some light line to capture the ring) . . . .see this picture from an Italian friend who (I think) makes the nicest looking rope work in the world.

Attachment 102524

Absolutely beautiful work!

[estarzinger]

Originally Posted by fallingeggs

Is there a preferred type of whipping thread to use for these applications?

Well, I use dyneema fishing line. Good UK resistance and terrific strength, and pretty inexpensive - a fishing roll will last you forever for whipping.

Originally Posted by Seaworthy Lass

Would you suggest not leaving two holes between insertions then?

I do not know that the optimal length is .. . . I just know it can be too far.

[arsenelupiga]

Originally Posted by Dockhead

By the way, great thanks are due from the whole community to Evans for this great work on knots and splices:

Load testing

A key reference!

excellent stuff, thanks. will get into it shortly. love dyneema.

[estarzinger]

Originally Posted by transmitterdan

It also appears that they use shrink tubing over a whipping. Can't really tell for sure. If it is shrink wrap be very careful. Dyneema does not like temperatures much above the temp at which the shrink tubing shrinks. One trick is to shrink the tubing by immersing in gently boiling (not rolling boil) hot water. This helps insure a tight shrink without over stressing the Dyneema strands.

I don't really like to use shrink tubing, primarily because the UV will eat it. (but it does work and is easy - and there is quite a wide variance in grades of shrink tubing and its UV resistance)

If you want to go with that method/look, I think the better method is to slide a decently snug fitting sleeve (Dacron or dyneema) on and sew it in place.

[transmitterdan]

Originally Posted by estarzinger

I don't really like to use shrink tubing, primarily because the UV will eat it. (but it does work and is easy - and there is quite a wide variance in grades of shrink tubing and its UV resistance)

Evans,

I agree with you about shrink tubing. Black shrink tubing is a little more UV resistant that other colors especially if it is the heavy wall thickness.

If you really want to be "cool" get PTFE heat shrink. It is UV resistant and translucent.

[Hudson Force]

After reading Dockhead's first post here early this morning I was motivated to pull out the 150' coil of Dyneema that I had stowed away. After reading through the rest of the thread I began searching for my set of fids and small marlinspike. I knew that I had moved them from my V-berth shelf some time ago.

I want to report great success! While searching through three lockers where I might have put these small fids, I found my missing case of cotter pins & rings as well as the silver engine "touch-up" paint and I reorganized and cleaned the three messy lockers!

I never found the little fids, but the Dyneema is out where I can keep my eye on it. I'll either clean & organized a few more lockers or break open a ball point pen. I'm impressed with how much I've gained from this splicing thread without begining a splice! ........'thanks

[transmitterdan]

Originally Posted by Hudson Force

I never found the little fids, but the Dyneema is out where I can keep my eye on it. I'll either clean & organized a few more lockers or break open a ball point pen. I'm impressed with how much I've gained from this splicing thread without begining a splice! ........'thanks

I like going on a treasure hunt in the boat. I always find something I forgot I had.

You don't need fids to splice Dyneema. You can make a "wire fid" using a coat hanger. Take a piece of the smallest coat hanger wire you can find (smaller is better) and fold it into a tight U shape. The U should be narrower than the rope dia. Mark the wire "fid" with electrical tape at the 3 correct lengths (number of dias) for marking the rope. Use the tape marks to measure and mark the rope. This is a "poor man's" version of the tool that Brion Toss calls a splicing wand. With this and a normal marlin spike and you can splice as much as you like.

For burying the tail inside the braid feed the U shaped coat hanger up from the bottom mark through the center of the braid and out. Put the tail of the tail in the U and pull the wire back through. It will pull the tail all the way through the braid and out. It works better than a fid in my experience.

[Hudson Force]

Originally Posted by transmitterdan

.......................

You don't need fids to splice Dyneema. You can make a "wire fid" using a coat hanger. .....................

Thanks, I had a similar idea when I looked among the case of cotter pins I came across. I have one cotter pin that is exceptionally long and thin that I think would do the job.

[pacific_voyager]

One trick I use for splicing Dyneema is to lock-stich with a contrasting color. If you ever need to pick apart the splice (e.g. lifelines) it is easy to do if you can find the lock thread.

Here is a good tutorial from Grog Knots on making a Brummel eye splice:
http://www.animatedknots.com/brummel/

[Sysunday]

Two small YouTube’s I recently made:
1. How to make a short uncovered dyneema loop with sufficient bury length:

https://www.youtube.com/watch?v=c0FXGTPV440

2. How to make a covered dyneema loop:

https://www.youtube.com/watch?v=FZVhCHHKVKM