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  1. #1

    Slipping dyneema ucr

    Gday all,

    I've been playing with 3mm Dyneema (SK75 1400kg rated, I suspect is is made in Australia)and got to making up a UCR for a hammock ridge line so I could play around with the 83% length thing. It all went well and I was following Jeff Myers and Tac blades video. I have ended up with a 26cm/10.23" part that is completely buried. It slips pretty easy as I sit down to get into the hammock. I used 2 colours, one for the ridge line and one for the bury/shuttle. The shuttle/Red Dyneema is quite different in feel to the grey ridge line dyneema. The grey is far more waxy and stiff while the red shuttle is quite supple, not waxy and gets "fluffy"...
    This is the red, and I bought the grey from the same place. https://www.ebay.com.au/itm/203257446987

    What to do to get the 83% right for me? Buy some more grey, impregnate with candlewax maybe. Is this a thing with dyneema. I did ask the supplier and they said maybe different batch but this would be ebay standard cya to stay in business... I may go to a fixed length dogbone but then I am stuck at the fixed length. They also sell SK78.

    Thanks for getting me hooked into Hammocking, what a rabbit hole!

  2. #2
    joe_guilbeau's Avatar
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    https://dutchwaregear.com/2016/02/19/amsteel-101/

    About half way down the page...

    What Size Bury for Amsteel 7/64?
    Samson specifies that a fid is equal to the diameter of the rope x 21, and that an effective bury for Class 2 rope should be three and a half fids. The diameter of Amsteel 7/64 is 0.11 inches, so for this rope, one fid is equal to 2.31 inches. So the recommended bury would be about 8 inches. Bury = fid x 3.5 = 2.31 x 3.5 = 8.01 inches Note that the length of the bury is dependent on the diameter of the rope. Counter-intuitively, the smaller the diameter of the rope, the shorter the bury needs to be. For example, a whoopie made with 1.75 mm Zing-it would only need five inches of bury (if following Samson specs), while one made with 1/8 inch Amsteel would need nine inches.


    Try a 12" bury and see how she goes.

  3. #3
    Senior Member cmoulder's Avatar
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    Not knowing how well versed you might be with UCRs, I wonder if the non-load end of the outer cord is adequately secured, and how.

    Some instructions show a prusik or other friction knot being used to maintain tension on that "free" end, with the prusik being made from excess length of the outer cord itself. Dyneema really isn't a good material for prusiks, etc. In fact it's horrible, and I suspect this might be the problem.

    What you might try is using a smaller-diameter polyester cord to make a prusik that will grip the Dyneema much better, then tie that to the non-load end.

    Five Basic Principles of Going Lighter (not me... the great Cam Honan of OZ)
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  4. #4
    Phantom Grappler's Avatar
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    You might have made a perfectly good UCR splice, possibly the rope used was extra slippery.

    Regardless of cause, rope too slippery, splice length a bit short, it’s no fun when your UCR slips

    I’ve never used a UCR, I use a fixed length non-adjustable 1/8 inch amsteel for my hammock ridgeline set at roughly 83%

    Both Joe and cmoulder, have given excellent advise that will most likely work on amsteel, as it’s complete and up to date, top quality knowledge available.

    I have an experimental method for making a slip-proof UCR…I GarnaUtees it will work.
    Start with some amsteel
    1/8 amsteel and 7/64 amsteel
    Splice your UCR with 1/8 amsteel as your inner bury, inside your 7/64 amsteel as your outer bury or sheath.
    It’s very difficult to splice 1/8 inside of 7/64 amsteel
    Allow extra length for 7/64 section, because it shrinks more because it’s going outside the fatter 1/8 amsteel.
    This will hold like a ravenous dog on a hunk of meat.

    Another independent solution is to set UCR and tie a slip knot on inner amsteel as it exits the bury (the loose end that dangles free)
    The slip knot will be too fat to enter the bury.

    I use a fixed length amsteel hammock ridgeline.
    If I ever needed to shorten my ridgeline, to get more sag or to pull further under tarp during rain. I could shorten it by coil wrapping amsteel multiple times around spine of carabiner with the last wrap going back around first wrap, to keep coils compact.

    Regardless, Good Luck

  5. #5
    all secure in sector 7 Shug's Avatar
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    It is the nature of UCRs to slip if not held by the tail. You can see some detail in my video 5:56 in below.
    A whoopie sling may be a better option for a ridgeline.
    Remember that 83% is just a starting place.
    Shug



    Whooooo Buddy)))) All Secure in Sector Seven

  6. #6
    Senior Member WV's Avatar
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    All good advice above. Note particularly cmoulder's concern about the tension on the non-load end of the bury. Elsewhere I have seen people suggest using a separate piece of small diameter bungee (1/16"?) whipped around the mouth of the bury to constrict it, but not attached to the main line with a prussick or klemheist knot. I have never tried this, because I was dubious. It would make adjusting the ucr length easier though, if you remembered to do it carefully.

    My personal choice (don't try this at home, kids) is ucrs made with 1.8 mm dyneema (Emmakites 900 lb. test, they say) with the non-load end secured by a prussic (or a klemheist) made with 1/16" bungee cord. Remember that a ucr is doubled, so it's potentially twice as strong as a single strand. A skinny ucr that holds is "stronger" than a heavy Amsteel one that slips. Pay attention to the coating and test carefully. If one slips, make a longer one, and make sure the non-load end gets loaded artificially (every time).

    Disclaimer: I use the 1.8 dyneema because it's similar to Dynaglide, has a nice coating, and it's easy to splice with a loop turner. I can use it for main suspension lines, as well as ucrs and bridge tendons because I weigh 140 lb. Your acceleration due to gravity won't vary, but your ucr's coefficient of friction may.
    loopie_sling_001.jpgThis one is actual dynaglide, used in a loopie sling. The bury and the non-load bungee loop are pure ucr, with a very conservative 10" bury.
    Last edited by WV; 04-16-2022 at 21:20.

  7. #7
    LowTech's Avatar
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    Not the best morning for me, wrote out a long (for me) detailed reply and posted it to the wrong thread . . . then deleted it by accident when attempting to move it.

    Anyway, I use UCR's for my hammock suspension fairly often. If you made yours from the Myers tutorial then you should already have the tail end attached to the main line. Though I do think that @cmoulder 's method is better.

    My thoughts on a UCR for a adjustable sag angle are that I never, ok rarely, have my ridgeline guitar string tight, and if my suspension angle is around 30° then I'm not really setting the UCR hard enough. Should it still work? Yes, but I would expect it to want to slip and would be milking it more than once while set up.

    If I was going to set up a hammock w/ an easily adjustable sag I would go w/ the concept that has been discussed here before and use a continuous ridgeline, like I have for my tarp and then hang my hammock off it from two UCR's. Of course this method has its own issues but I find it interesting enough that I'll probably work one up at some point and see how it plays.

  8. #8
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    I don’t think the bury is too short. If it was, it might not be good for 1400 kg strength of the cord but it would still hold at a lesser amount like say 1000 kg.

    I have made my ridgelines as a whoopie sling, noting however that the length is tailored to a targeted 83% length with maybe 5 or 6” plus or minus of adjustment, so a fairly small loop and short tail.

  9. #9
    Senior Member Baka Dasai's Avatar
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    Quote Originally Posted by DrPhun View Post
    ...I have made my ridgelines as a whoopie sling, noting however that the length is tailored to a targeted 83% length with maybe 5 or 6” plus or minus of adjustment, so a fairly small loop and short tail.
    This is the best answer. Whoopie slings are easier and more reliable than UCRs, and the extra amount of cord required is close enough to zero in this use case to not be worth thinking about.

    Sent from my Pixel 5 using Tapatalk

  10. #10
    Thank you for all your replies, so much to digest but I need to reply as all of the above was so helpful.
    I have added a photo with a mason line continuous loop/prusik that I added..it still slipped straight away, I think the grey is really slippery.
    The photo has Tac Blades Shackle in red-Jeffs evo loop with tacs knot in grey-a sawyer filter mesh bag to hold it all-Jeffs shuttle..etc.
    There is grey colour transfered instantly onto both the red knot and the mason line knot.

    This is my list.
    1. A longer 12" bury As Joe mentions
    2. Some other cord type to try the prusik way again as Cmolder mentions.
    2. Some beeswax to make the rope stickier or even dissolve some of the wax coating off with metho.
    3. 1/8+7/64 UCR per Phantom Grappler. I like this to counter the slippy rope but I have no 7/64.
    4. Fixed length dogbone with a second shorter one to loop around similar to Phantom Grappler mentions. Also good.
    5. a whoopie sling, but I will feel defeated!

    I have noticed that the ridgeline is not guitar string tight as fellow nomad Lowtech mentioned, I like to use it to get out of the Hammock.
    A continuous rigdeline with two URCs..I see more Dyneema purchases in my future.

    I need a lie down
    Thank you

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