Another PR Knot question

Discussion in 'Tackle and Rigging' started by wanna be tuna slayer, Mar 25, 2009.

  1. Hey guys,
    I've been tying some Page Ranking knots and pulling on them. I am currently tying them with 65lb tuf line xp and 80lb varivas. The other day I hooked one up to my weight machine. I was able to lift the 50lb plate, then it snapped just on the 60lb plate(also leaving a small hole in the thumb that was near it!). I am perfectly satisfied with 50+ lbs of pressure, but I was wondering if my knot failures are at the same point as others have observed. Here is a pic. Is this where your Page Ranking knots snap when pushed to failure?
    [​IMG]
     
  2. John_Madison CT

    John_Madison CT Senior Member

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    I've been hit by braid and mono snapping under pressure. It leaves quite the mark and hurts like a mother.
     

  3. Yep, i think the mono snapped back and put a nice puncture wound in my thumb! Hurt like a SOB!
     
  4. BretABaker

    BretABaker Guest

    where did it break? theres no pic
     
  5. The pic shows up for me, is it not there when you look? Huh, let me try to do that again. Anyway it breaks right at the end of the knot, or where the turns are reversed.

    Did that work for the pic?
     
  6. BretABaker

    BretABaker Guest

    yeah i see the pic. so it breaks where you switch direction of the wraps?
     
  7. Bret,
    Well it usually breaks right at the end of the braid wraps. It looks to me like it is compressing the mono more at that spot and it fails. It seems like I may need to try and wrap tighter towards the other end of the knot to try and spread some of the pressure towards the other end for a more even "squeeze."
     
  8. d-a

    d-a Senior Member

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    Have you tested the leader? Looks like the leader is breaking at the knot. The knot looks to be holding perfectly. Take the knot apart and make sure the leader is still under the wraps.

    d-a
     
  9. d-a, the leader is still in the knot, it breaks right at the end of the knot. Where do your breaks occur when you take it to failure?
     
  10. d-a

    d-a Senior Member

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    d-a, the leader is still in the knot, it breaks right at the end of the knot. Where do your breaks occur when you take it to failure?

    Never that close to the knot. However I still think your leader is breaking instead of the knot.

    d-a
     
  11. BretABaker

    BretABaker Guest

    it could be your wraps are TOO tight and squeezing the leader way too much which is what I think Doug is saying. i had that happen when testing a super tight knot. it was just too much 'gripping' pressure on the soft leader and the braid cut into the mono.
     
  12. NEMO

    NEMO Member

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    Same hear, the only knot I'll ever use.
     
  13. d-a

    d-a Senior Member

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    The leader is going to stretch until it can not stretch anymore. Then it's going to break at the weakest part. That part is where the leader stretched the most and not stretched at all(under the wraps). When you was testing the knot, did you apply the weight gradually or in a quick,snapping way?

    d-a
     
  14. Gozz

    Gozz Senior Member

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    I do the knot super tight.
    If I don't it seems to slide off so I do the first lot of wraps and then tighten it as much as I can and then finish it of with about 7-8 wrap lock knot.
    I use 80pnd braid on 120pnd leader.
     
  15. Hey guys,
    Well I've learned something this morning, I think. When I was tying the knot before today, I was not allowing the bobbin to stay in contact with the leader when wrapping it so my wraps weren't as tight as they could have been.

    The weight machine is at a friends house so I don't have it to use all of the time, but I have been tying the braid to a round metal table with a uni knot and pulling on it to failure.

    After I started making the wraps much tighter, the system started to fail at the uni in the braid attached to the table. I guess this means the knot is holding up better. I think when the wraps are too loose and a lot of weight is put on it, the first area to cinch down is that top region. It pinches it down too much in that area causing the failure. If all of the wraps are done very tight at first, then it is a more even squeeze throughout the knot. I have noticed on the first knots that failed at the leader, that the knot did look much tighter in that area than the rest of the knot.

    Does this sound right?
     
  16. pametfisher

    pametfisher Senior Member

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    If it were me, I would check the actual breaking strength of the mono before I worried more about the knot. Take a four foot piece (or so) put a good twenty turn Bimini in each end. Put one Bimini in a 200 lb. snap swivel put the other through a 1" dowel. Connect the swivel to your load, pull with the dowel. The reason to double the line is so that you're measuring the strength of the line, not the knot at the ends.

    From the photo, as others have pointed out, the knot looks fine. Also as others have said, you've got a stress concentration point at the top of the P.R. knot perhaps you make it in a way that it's too tight there--a suggestion but it's hard to tell over the internet. ;)

    Mono stretches first and then it fractures. As you found out, there's a lot of energy stored up in the stretched mono. You should really have on gloves and safety glasses (you could easily lose an eye) when you do this and keep the piece of mono short--the longer the mono, the more energy is stored.

    I would think that your P.R. should not fail, the mono should, at about 70 lbs. or so, assuming that the actual breaking strength of your line is 70-75 lbs.

    Line strengths vary a lot. I just got some 60# hollow that will lift over 102.5 lbs.!

    One way to make mono stretchy is to use line that barely meets its rating. In other words, a 65# test line that is actually 60# will stretch a lot more than 65# line that tests to 80#.

    When you come right down to it, the strength of Brand A versus Brand B has a lot to do with how much material they use. This is especially true in Spectra. Strength is HIGHLY correlated with the amount of material.
     
  17. Pametfisher,
    Thank you. I think I am going to try and test the mono.
    That hand that got slapped was the only bare area showing. I had a big glove on one hand, glasses on and I turned my head. I was stupid and had that bare hand just barely bracing the gloved hand. That was pretty painful.
    Thanks for the help.
    Al