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Re: hammock ridgeline stresses

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  • Dave Womble
    Greg, I was talking about selecting a rope for the hammock suspension line, or the line you attach to the tree. It is different than the ridgeline. I was also
    Message 1 of 3 , Jan 2, 2006
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      Greg,

      I was talking about selecting a rope for the hammock suspension line,
      or the line you attach to the tree. It is different than the
      ridgeline. I was also concerned about the hammock suspension line being
      more than strong enough for a range of conditions and my feeling is
      that a structural ridgeline can greatly add to that range of conditions-
      - especially if one initially sets the hammock suspension lines taut,
      stretches the hammock system out by getting in or on it and then
      retensions the hammock suspension lines.

      It you look at this diagram, http://tinyurl.com/b8jl8 , it is one I put
      together in an attempt to show what is going on. I hope I got it
      right, it uses vectors and when I went to school it was how one went
      about defining forces in complex structures. It is based on Neutons
      laws of motion, which have stood the test of time for hundreds of years
      without exception. Hammocks have a degree of complexity as far as
      force calculations go and a structural ridgeline certainly adds to
      that. It is customary to use vectors to help simplify the mathematic
      models.

      But, like you mention one can set up simple physics experiments to
      either prove or disprove the results and I think that is great thing to
      do if one is so inclinded, I did myself to convince myself of the
      charts I found in an article I read that was written by cave rescuers.
      That article described the forces on the suspension lines but I don't
      recall it describing the forces on a structural ridgeline itself. This
      is a link to a pdf file for part 3 of that article:
      http://www.draftlight.net/cgi-bin/download.pl?file=3 , the load
      analysis starts of page 6 of 61.

      Dave

      --- In hammockcamping@yahoogroups.com, Greg Welker <gdwelker@v...>
      wrote:
      >
      > Dave, I'm familiar with the Hennessey - it's one of the ones I
      > own. You said:
      >
      > >but my guess is worse case would be 3 times as much, but I would
      > >certainly plan on at least twice as much.
      >
      > Remember the guy who did the cutting of the hennessy ridgeline and
      > inserted the carabiner? If you did that, you could easily insert
      > something like a fish weight hanging scale and determine the strain
      > in the ridgeline. Testing the strain in the ridgeline I can't see
      > that it holds a significant portion of the force vector that is on
      > the hanging ropes, especially not to the point that you need to
      > consider that load in your hanging rope calculations.
      >
    • Bill in Houston
      Take a look at Dave s work. It will make sense. The ridgeline really can have a lot of tension in it. Or try the scale experiment. Sounds interesting. Bill
      Message 2 of 3 , Jan 3, 2006
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        Take a look at Dave's work. It will make sense. The ridgeline really
        can have a lot of tension in it. Or try the scale experiment. Sounds
        interesting.

        Bill in Houston

        --- In hammockcamping@yahoogroups.com, Greg Welker <gdwelker@v...>
        wrote:
        >
        > Dave, I'm familiar with the Hennessey - it's one of the ones I
        > own. You said:
        >
        > >but my guess is worse case would be 3 times as much, but I would
        > >certainly plan on at least twice as much.
        >
        > Remember the guy who did the cutting of the hennessy ridgeline and
        > inserted the carabiner? If you did that, you could easily insert
        > something like a fish weight hanging scale and determine the strain
        > in the ridgeline. Testing the strain in the ridgeline I can't see
        > that it holds a significant portion of the force vector that is on
        > the hanging ropes, especially not to the point that you need to
        > consider that load in your hanging rope calculations.
        >
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