There seems to be many pages dedicated to the search for an ideal Dyneema bend over the past 5-6 years.
It is easy to get lost in the current state and difficult to make a clear comparison.
It also seems there are several front runners for Bends in Dyneema, depending on the benefits/drawbacks one would prefer.
I wonder if it is possible to do a comparative analysis on the breaking strength of the following options.
Here is a summary, as I understand it, from perusing the forums to date, in no particular order.
Please correct me, as I’m sure to have stumbled a bit here.
I hope this helps to organize the current state of options a bit:
The “First Bend” (and its variation at 10% stronger):
Reference: http://l-36.com/no_slip_knot.php
Basic Structure: Built on a carick-type bend with ends backwards and retucked through the center - it is a bend version of the diamond knot
Benefits: Easy to tie, aesthetically pleasing; Stronger than Triple Fisherman’s, can be untied using a spike to loosen the center
Drawbacks: Slips under rapid loading ~32% (but at higher load than Triple Fisherman’s); bulky;
Note: This seems like the knot to choose as long as you are willing to preload it. If you preload the knot and pull tight on ends (especially the variation), the knot won’t slip and it then seems stronger than the Dangler bend. http://igkt.net/sm/index.php?topic=4756.msg39864#msg39864
A good explanation of what makes this bend work here: http://igkt.net/sm/index.php?topic=4756.msg30897#msg30897
The “Last Bend”
Reference: http://l-36.com/bend_knot.php
Basic Structure: Built by looping two buntline hitches together but using a figure 8 instead of a clove hitch style, then weaving the tails through opposite loops. Put another way by Xarax, it is an asymmetric variation of a side-by-side pretzel bend.
Benefits: Doesn’t slip; easy to tie, achieves ~39% of line strength
Drawbacks: A bit Ugly according to its originator, cannot be untied
Double Estar Hitch
Reference: https://www.hammockforums.net/forum/archive/index.php/t-118427.html
Basic Structure: The Estar Hitch is merely a Buntline Hitch but with the end tail looped back around the hitch loop piece, through and alongside the standing end
Benefits: Does not slip, efficiency is 45-50%
Drawbacks: ?
Nautiknot’s “Twofold Overhand Bend” and its related alternatives
Reference: https://igkt.net/sm/index.php?topic=5935.msg39963#msg39963
Basic Structure: Twin overhand bends with half-hitch finishes
Benefits: ?
Drawbacks: Can’t be untied after loading
Triplenip knot
Reference: http://igkt.net/sm/index.php?topic=6026.0
Basic Structure: Reever variation with additional interweaving
Benefits: Thin knot,
Drawbacks: Difficult to dress
It seems like manufacturers don’t intend for Dyneema to be knotted, instead marketing it as a replacement for wire rope. This reality may save a mountain of slippery frustration.
And the point of his post may also be correct (from a certain point-of-view).
Having said that, it would be interesting to study the behaviour of a knot specimen tied in kernmantel type EN892 or EN1891 rope and then the same knot tied in a brand of dyneema type rope - perhaps in a side-by-side test?
Are there any studies performed on the Zeppelin bend using dyneema rope (I admit to being lazy and not doing a google search or IGKT search…because I am sure that someone will quickly reply!).
I think some testers have found the tripled version of #1415 (Double Fishermans) to be secure in dyneema? (need verification).
Hi Mark,
If the Zeppelin doesn’t work with Dyneema maybe some retucked versions could work. In particular I have tied a locked slipped Zeppelin and a collared (slipped) Zeppelin…I will post some pictures asap.
About the “slippery frustration”, I think it can help to better understand how the used bends work.
Ciao,
s.
Hello All,
I probably should have mentioned at the beginning of the post that dozens and dozens of variations of all the typical bends and approaches to knotting have been attempted and written about extensively in this forum.
What I chose to summarize were the last remaining options that were at least acceptable based on user preferences. It was difficult to determine which of these bends were strongest from the existing conversations.
So… if you have a commonly known bend or variation of that bend in mind, you will not be surprised to find that it has been discussed quite a bit in the forum.
Thanks
mikesplan, I am somewhat curious about the testing you had done.
In reading through your posts (and links to photos) - it appears that raw MBS yield (ie strength) is dominant in your thought processes.
Did you look at data points for security and stability?
For example in terms of ‘security’ - the load threshold at which specimen knots began to slip.
Did you observe slippage immediately when load was applied or did slippage only commence later - after a certain load threshold had been passed?
Raw MBS yield seems to dominate many peoples thought processes and also takes ‘pole position’ in many test reports. It would be nice to see other data points too.
At this link; http://l-36.com/bend_knot.php I note that you ‘tested’ the tripled version of #1415 (Triple fishermans bend). I would be most interested to understand at what load did slippage commence? Did the knot start to slip immediately upon application load or did it start to slip at a later time - ie once a threshold had been passed?
If it didn’t slip immediately as load was applied, perhaps slippage commenced at:
at 10% of MBS yield
at 20% of MBS yield
at 30% of MBS yield
and so on…
Maybe slippage commenced one 50% of MBS yield had been reached? If this is the case, that information might be useful to understand…
From what I can glean from your test rig photo, it appears that you tested 2 knots in-line (both existing in the same test cord simultaneously) - instead of testing them separately. Am I seeing this correctly? If yes - this could skew your test results when one of the knots starts to slip before the other.
Hi Mark,
I’m sorry for the confusion. I did not do these tests. I included the references to help point purple to the final remaining options based on input from many people in this forum.
I plan to setup a testing mechanism soon and will post data once obtained.
My hope here is to make sure I have all of the best options identified.
Best regards,
Mike
Thanks for replying Mike.
The more people we have doing knot testing - the more data points we will have - which is a good thing.
So please keep testing!
If I may make a few requests…
And this data would be included in future updates to some of my papers on various knots:
End-to-end joining knot test
Measure the threshold load at which the Zeppelin bend begins to slip (ie this investigates ‘security’)
In relation to #1, please report on the type of dyneema cord you use (ie cord diameter, make, unkotted MBS).
The ‘control’ for the test would be the identical knot tied in non-dyneema cord (eg a ‘kernmantel’ type cord such as a cord made by Sterling USA).
The same type of test - but with #1415 double fishermans
The same type of test - but with a tripled version of #1415 (ie triple fishermans)
Please dont mix different knots in-line along the same length of test cord (only test one knot specimen at a time).
As for test configuration, you have 2 options:
Round sling configuration:
Form a round sling from 1 length of cord, using a single end-to-end joining specimen knot; or
Form a round sling using 2 identical lengths of cord - so you have 2 knot specimens (ie dual identical knots).
Linear configuration:
join 2 identical lengths of cord using the knot specimen
You will have 2 free ends which must be properly terminated
Suggested termination is via #2047 ('tensionless hitch) - which is also clamped back to its own SParts to prevent any slippage
Configuration 1 is easier to work with in my view - since you have no ends to terminate in the test rig.
Keep in mind that that using a sling configuration raises the loading (approximately doubles it) - so you need to take that factor into consideration when measuring loads.
Avoid direct cord-to-cord terminations because this will create friction points which cause heat build-up with risk of skewing the results. Try to link the cord to a shackle or an old steel carabiner.
Hi Mark,
Excellent ideas and recommendations. I had not considered using a control line for comparisons.
I also planned on buying a winch, but would be interested in any ideas you may have for moderately priced testing station to build in a garage?
Thank you,
Mike
Load cell (tension type): Not sure what you currently have.
The ‘enforcer’ is a great little tension load cell made by Rock Exotica.
I like that it have swivel eyes and can interface to your cell phone via an app.
Link: https://www.rockexotica.com/enforcer-load-cell/
However, it is limited to 20kN (approx 2000kg) - meaning that it wont be able to reach the MBS yield of 11mm kernmantel type ropes. But, if you stick to cords/ropes not greater than 20kN MBS you should be okay (assuming you want to reach the MBS yield?). If you are only examining knot security, then you can of course use cordage that has a higher MBS yield.
I’m not sure if you had been borrowing someones load cell for your previous testing?
The sampling rate (which is very important) for the enforcer is selectable up to a max of 500 Hz (500 samples for second). With any load cell, you need to have at least (minimum) 100 Hz sampling rate otherwise you will not get accurate results.
…
As for a winch, to save a few $$, a hand operated winch is the way to go. You need a reasonable amount of ‘stroke’ - the amount it can winch and take up before it reaches its travel limit.
If you stick to 2 metric tons, a 2 ton ‘lever hoist’ is reasonably priced.
Link: https://www.alllifting.com.au/lever-hoist (note - this link is just an example…you can buy lever hoists at most lifting/rigging supply shops in your local area).
EDIT NOTE: The capacity of the load cell will dictate the capacity of the winch mechanism.
For example, if you purchase a 20kN (2 metric ton) rated load cell, then you would only need a 20kN (2 ton) winch. The load cell would be the limiting factor.
In my view, the Rock Exotica ‘enforcer’ load cell is a great device and has sampling rate of up to 500 Hz (sampling rate is crucial and defines the accuracy and quality of the measurements). But, you are limited to 20kN force.