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Rope tension

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  • polecatpop
    Treehangers: I just got my HH and immediatly hung it up on two trees I planted just for this occation 11 years ago. I tried to follow the group advice and put
    Message 1 of 5 , Dec 15, 2003
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      Treehangers:

      I just got my HH and immediatly hung it up on two trees I planted
      just for this occation 11 years ago.
      I tried to follow the group advice and put the tree huggers at eye
      level etc and cinch it up pretty tight.
      The sag still had the hammock bottom (and mine) about a foot off the
      ground. Not bad for a test.

      So I started thinking about the tensions at various angles......

      Assuming I weigh about 200 pounds and the weight is evenly
      distributed between the two ends. Using the force diagram triangle.
      Tension in the rope equals 1/2 my weight divided by the sine of the
      angle below horizontal.

      So if the rope angle is 15° the rope tension is 386 lbs.

      1 ° 5729.9
      5 ° 1147.4
      10 ° 575.9
      15 ° 386.4
      20 ° 292.4
      25 ° 236.6
      30 ° 200.0
      35 ° 174.3
      40 ° 155.6
      45 ° 141.4

      As you approach a flat no sag condition, the tension approches
      infinity.

      Finally found a practical use for that high school trig.

      The tighter the rope, the better the hang, but the more force on the
      rope, knot and tree.

      O great wizards of the woods.... What angles are you using for
      utmost stability and comefort?

      Ralph

      PS If anyone would like a copy of the spreadsheet so they can
      calculate their stress level, give me a holler.


      PPS Risk: Now we can calculate what it would take to hang a
      hammock in a snow cave.

      PPPS Perhaps if the people who want to hang a hammock in their
      rooms could also use this data? Seems to me a ceiling hang would be
      easier than a wall mount.
    • Mirage
      ... wrote: ... I d love a copy, but why not put it in the Files section of the group web site. That way you don t need to keep sending it.
      Message 2 of 5 , Dec 15, 2003
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        --- In hammockcamping@yahoogroups.com, "polecatpop"
        <polecatpop@y...> wrote:
        ...
        > PS If anyone would like a copy of the spreadsheet so they can
        > calculate their stress level, give me a holler.
        >

        I'd love a copy, but why not put it in the "Files" section of the
        group web site. That way you don't need to keep sending it.

        > PPPS Perhaps if the people who want to hang a hammock in their
        > rooms could also use this data? Seems to me a ceiling hang would
        > be easier than a wall mount.

        Not following here? Easier to attache the eye bolts? Or easier on
        the stud WRT stress loads?

        Thanks for taking the time to run the numbers...

        Shane "Mirage"...
      • polecatpop
        ... You guys got files? cool It s posted Thanks for the suggestion ... on ... I guess my thinking is a bit muddled. Rather than pulling the wall studs
        Message 3 of 5 , Dec 15, 2003
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          --- In hammockcamping@yahoogroups.com, "Mirage" <web_dawg@y...>
          wrote:
          > --- In hammockcamping@yahoogroups.com, "polecatpop"
          > <polecatpop@y...> wrote:
          > ...
          > > PS If anyone would like a copy of the spreadsheet so they can
          > > calculate their stress level, give me a holler.
          > >
          >
          > I'd love a copy, but why not put it in the "Files" section of the
          > group web site. That way you don't need to keep sending it.

          You guys got files? cool It's posted

          Thanks for the suggestion






          >
          > > PPPS Perhaps if the people who want to hang a hammock in their
          > > rooms could also use this data? Seems to me a ceiling hang would
          > > be easier than a wall mount.
          >
          > Not following here? Easier to attache the eye bolts? Or easier
          on
          > the stud WRT stress loads?



          I guess my thinking is a bit muddled.

          Rather than pulling the wall studs in I am thinking of using the
          ceiling joists as a compression member of a frame.

          At tight angles (high tension) the forces get quite large.

          But I'm just not sure what practical angles are in actual use?


          Some things to discuss????








          >
          > Thanks for taking the time to run the numbers...
          >
          > Shane "Mirage"...
        • Dave Womble
          Ralph, You may or may not be aware of this so pardon me if you already knew this. The Hennessy Hammock that you are using is fundamentaly different from the
          Message 4 of 5 , Dec 15, 2003
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            Ralph,

            You may or may not be aware of this so pardon me if you already knew
            this. The Hennessy Hammock that you are using is fundamentaly
            different from the Speer Hammock (and probable most others as well)
            in that it incorporates an integral hammock ridgeline. This integral
            hammock ridgeline sets the sag of the hammock and in practice makes
            the sag of the hammock support lines a non-issue, except for the
            loading and stress of the the hammock support lines and the hammock
            ridgeline. I think the stretch in the nylon tree huggers on the HH
            prevent you from actually loading the hammock support lines much over
            about 15 to 20 degrees (just my guess) unless you work real hard at
            pulling the hammock taut (which is something you don't want to do).

            With the Speer Hammock, the hammock sag is determined by the sag of
            the hammock support lines so they directly effect the comfort, or sag
            if you will, of the hammock.

            Dave

            --- In hammockcamping@yahoogroups.com, "polecatpop" <polecatpop@y...>
            wrote:
            > O great wizards of the woods.... What angles are you using for
            > utmost stability and comefort?
            >
            > Ralph
          • polecatpop
            What a great group Yes, These are dead weight static values. They should be considered a starting value for any real safety factors etc. Obviously Ed and Tom
            Message 5 of 5 , Dec 15, 2003
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              What a great group

              Yes, These are dead weight static values. They should be considered
              a starting value for any real safety factors etc. Obviously Ed and
              Tom with their respective geniuses have already taken into account
              dynamic loading and safety factors.
              I thought it was just a way to see what stress we were putting on
              the tree.




              If I understand Daves point, it doesn't matter how tight I hang my
              HH, the required sag is set by the ridge line. As long as I get the
              ridge line tight, but not to tight, all should be well.


              What a group, thanks for all the input




              Ralph







              --- In hammockcamping@yahoogroups.com, "Dave Womble" <dpwomble@y...>
              wrote:
              > Ralph,
              >
              > You may or may not be aware of this so pardon me if you already
              knew
              > this. The Hennessy Hammock that you are using is fundamentaly
              > different from the Speer Hammock (and probable most others as
              well)
              > in that it incorporates an integral hammock ridgeline. This
              integral
              > hammock ridgeline sets the sag of the hammock and in practice
              makes
              > the sag of the hammock support lines a non-issue, except for the
              > loading and stress of the the hammock support lines and the
              hammock
              > ridgeline. I think the stretch in the nylon tree huggers on the
              HH
              > prevent you from actually loading the hammock support lines much
              over
              > about 15 to 20 degrees (just my guess) unless you work real hard
              at
              > pulling the hammock taut (which is something you don't want to do).
              >
              > With the Speer Hammock, the hammock sag is determined by the sag
              of
              > the hammock support lines so they directly effect the comfort, or
              sag
              > if you will, of the hammock.
              >
              > Dave
              >
              > --- In hammockcamping@yahoogroups.com, "polecatpop"
              <polecatpop@y...>
              > wrote:
              > > O great wizards of the woods.... What angles are you using for
              > > utmost stability and comefort?
              > >
              > > Ralph
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