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[ksurf] Re: Knots vs splices, was AW: AW: No Subject

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  • Dave Culp
    ... Knotting any line, let alone kitelines, reduces its strength by 40-60%. It is quite possible to splice spectra kitelines; I ve done it for years. Splicing
    Message 1 of 3 , Dec 2, 1998
      >O.K i think a security is necessary for extrem kiting.
      >But the most problem of breaking lines are the knots.
      >There has to made some improvements or test for the best,
      >because to have thinner lines results in better upwind
      >performance. Maybe 3/4 of w. is to extrem but something
      >in the middle?.
      >The use of 100 kg instead of 200 kg lines is a reduction
      >of 500cm" (2lines) or 1000cm" (4lines) by a length of 30m.
      >
      >Only some facts to discuss.
      >
      >regards

      >Henning Carstens

      Knotting any line, let alone kitelines, reduces its strength by 40-60%.
      It is quite possible to splice spectra kitelines; I've done it for years.
      Splicing returns 90%+ of the line's original strength. It is difficult,
      however, to sleeve the lines after splicing (you have to pull the loop
      inside, *through* the lollow braid. This isn't possible with a sleeve,
      too). So, the finished loop needs a sewn-on sleeve, or reeving it round a
      small plastic or stainless thimble, for abrasion protection.

      As I said a month or so ago, you can learn to make a "no-knot" splice
      either by buying a specialized "no-knot" needle, with instructions, from
      any good kite shop, or you can go on the web and look for the
      instructions (the specialized needle is not needed--a long, thin piece of
      wire, bent double, will work). I believe I saw the instructions indexed
      (linked) somewhere on The Kiteflier's Site: http://wwwkfs.org/kites

      Alternatively, you can sew the line into a loop, and neither knot *nor*
      splice it. This is how parachutes are made. Double the line back on
      itself (inside a sleeve, as you do with knots) and run it several times
      through a zig-zag sewing machine. Amazingly, this will give you 80% (or
      so) of the original line's strength, if done even half-assed. Be sure to
      sew along a fairly long bit of line (couple of inches), and go back and
      forth at least twice.

      --
      Dave Culp Speedsailing dave@... http://www.dcss.org/speedsl
      Kite powered boats, high speed sailing, proas and more. Check it out!


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    • Mulder B.E. (Ben)
      I have been buggying for 7 years now and have never use lines stronger than 150 kgs and I am usually overpowered. I am 1.90 m (6 ft 5) and 90 kg heavy but even
      Message 2 of 3 , Dec 3, 1998
        I have been buggying for 7 years now and have never use lines stronger than
        150 kgs and I am usually overpowered. I am 1.90 m (6 ft 5) and 90 kg heavy
        but even with a crash or other emergencies I never broke a line unless the
        lines got cut by something (like barbed wire, kevlar lines of other kiter,
        seagull, boeing 747-400)
        I am quite new to kitesurfing as well but I tend to use stronger lines than
        with buggying because the strain on the lines are greater with a crash in
        the water than on land. On land you just get dragged along and so relieving
        high strain on the lines. You can imaging that there is higher strain on the
        lines when you go under water and the kite wants to go further. Once you are
        airborn there is little strain. ('to air is human!' says Cory)
        Furthermore I would like to react again on the of upwind capabilities
        comparing two- and four lined kites. I'm very sorry Pierce that I dared to
        comment on the master himself but... I am convinced that if you put up the
        same kites only one with two and the other with four lines of equal length,
        and note that I say equal length, the two lined kite flies more into the
        wind than the four lined. The remark that you can control a four lined kite
        better in that edge-area is a very sensible one. So maybe yes, you have a
        better upwind course with a four lined kite but because of better
        controlability but not performance. If I dive a two lined kite from high up
        to the edge of the windwindow that kite gets more speed than when you hold a
        four lined kite still in the same position (what most tend to do) and so you
        yourself get more speed. Don't get me wrong, I will probably be flying my
        four lined kites more, as I do with buggying, just because of controlability
        but I think that a two lined kite can perform better. I set my buggy
        speedrecord with a two lined framed kite.
        I have a set of 4 lines for my standard Quadrifoils of only 5 metres. Great
        performance in the windwindow but it overtakes you all the time, collapses,
        catches the wind again almost yanking you out the the buggy... really cool
        with high speed! ;-) But it can give you an advantage during a race. The
        longest set of 4 lines of me are 22 metres. The longest set of 2 lines of me
        are 45 metres.

        >>In a german kitemagazin was an article about some tests
        >>with different lines.
        >>result for traction you only need lines of 3/4 of the pilots
        weight, you
        >>do not need lines for 200 kg.

        >then consider when you are about to go for a jump and the wave lip
        crashes
        >down on you and pushes you to the bottom of the sea - then you are
        talking
        >about more than your weight ! maybe three times (you need a safety
        margin
        >!! )- if you are an 80 kg flysurfer (with board and acessories)
        then you
        >need 80 * 3 = 240 kg. Also the knots to connect weaken the lines -
        even
        >when protected i heard that by 30% (ok, i am not sure)

        >so 200 kg lines minus 30% can each hold 140 kg = total of 280 kg =
        compared
        >to the 240 above
        >sounds like 200 kg lines are about right !!


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