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  1. #21
    Senior Member TiredFeet's Avatar
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    Quote Originally Posted by Schneiderlein View Post
    I am not sure if there was an implication that structural ridgelines are good or bad in Youngblood's posts. I think what Youngblood posted is very helpful and lets the hanger make a smart decision about their suspension system and the kind of trees they hang from.
    I didn't say that either.

    And I agree that his posts are helpful. I just don't think that he gave the full story in considering modern ropes.

  2. #22
    Senior Member TiredFeet's Avatar
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    Quote Originally Posted by Schneiderlein View Post
    ...

    I plan on trying out a structural ridgeline to see if I like it. The graph tells me that the benefit of being able to attach at a lower point comes at the cost of a reduced safety margin. ...
    Actually the reduction in the safety margin is marginal with modern ropes. Modern ropes using modern fibers can comfortably hold more than you can subject them to hanging a hammock even with a structural ridge line.

    That is all I was trying to show. By solely emphasizing the forces involved and not discussing the role of modern ropes in handling the forces, I felt that Youngblood was maybe scaring people into thinking that the ridge line wasn't safe using modern ropes, where it actually is quite safe.

  3. #23
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    I'm sorry if I misinterpreted your post, TiredFeet.

    I think the reduction in safety margin can be quite substantial, if you can increase your force from 200lbf to 800lbf just by attaching lower. That reduces your safety factor from 6 to 1.5 if the weakest link in your suspension system is rated at 1,200lbf, as is the case with my straps. Even with high-tech straps and rope, I'd still be concerned about taking down a tree.

    I think what Youngblood posted actually applies to hanging your hammock whether you use a structural ridgeline or not. The forces increase dramatically as the angle between suspension line and tree becomes closer to 90 degrees. Withou a structural ridgeline, you wouldn't hang that way because it would be very uncomfortable. As I see it, the only potential problem with a structural ridgeline is that it does allow you to hang that way in comfort, but it doesn't mean you have to. So, they are not inherently unsafe, but you should use proper caution.

    As I said, I have never used one, so maybe Youngblood can clarify this?

  4. #24
    Senior Member NCPatrick's Avatar
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    Are we factoring in that trees also get wider at the bottom? I can't remember..


    "Civilization is the limitless multiplication of unnecessary necessities."
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  5. #25
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    Quote Originally Posted by NCPatrick View Post
    Are we factoring in that trees also get wider at the bottom? I can't remember..
    Not yet, but that's a great idea. I will update my finite element model, which also accounts for the moment on the tree roots being reduced the lower you hang...

  6. #26
    Senior Member NCPatrick's Avatar
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    Also need to account for the types of trees (acidity of the soil(?), tendency of certain trees to have shallow roots vs deep roots, whether it's windy out -- which way is the tree leaning, swaying factors, age of the trees, health of the trees, etc.).

    Just kidding Youngblood. I do see what you're saying.


    "Civilization is the limitless multiplication of unnecessary necessities."
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  7. #27
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    You are kidding now. But wait just a few minutes and someone will post that the moment actually remains the same as the force becomes more perpendicular to the tree.

    **** engineers (I'm one of them).

  8. #28
    Senior Member NCPatrick's Avatar
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    Well, it'll certainly enhance our collective knowledge!


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  9. #29
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    Quote Originally Posted by TiredFeet View Post
    Youngblood - I asked my girlfriend about your posts on the ridge line. Her reaction was that you are totally correct on the forces involved, but that she thought you also missing something.
    With a structural ridgeline, for any particular span you have a range of attachment heights where you can achieve the same hammock sag with the hammock the same distance above the ground. When you attach lower on the attachments you are using more force than you would if you attached higher. Beyond more force not being a good thing where reliability and possible damages to whatever it is attached to is concerned, there is another issue.

    When you tie lower, the hammock will also drop further when it is loaded versus when you tie higher because of the forces and geometry involved. This extra drop when the hammock is loaded does not make hanging a hammock easier, it does just the opposite and it can make hanging tarps close to the hammock more trying as well. I can create diagram(s) or you can try it yourself if you are interested, it is pretty easy to see when you know what to look for it. For those that want to analyse it, it is just a geometry problem that involves the cosine and tangent of small angles versus larger angles.

    My advise is to hang 'em high. This creates less stress on everything involved and you will have less drop when the hammock is weighted. And yes, when you do that you don't need a structural ridgeline as much to set the sag and you may discover that you don't need it at all.
    Youngblood AT2000

  10. #30
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    Quote Originally Posted by Schneiderlein View Post
    I think what Youngblood posted actually applies to hanging your hammock whether you use a structural ridgeline or not. The forces increase dramatically as the angle between suspension line and tree becomes closer to 90 degrees. Withou a structural ridgeline, you wouldn't hang that way because it would be very uncomfortable. As I see it, the only potential problem with a structural ridgeline is that it does allow you to hang that way in comfort, but it doesn't mean you have to. So, they are not inherently unsafe, but you should use proper caution.

    As I said, I have never used one, so maybe Youngblood can clarify this?
    You have it figured out but we have always used the horizon as the zero angle reference instead of the vertical axis.
    Youngblood AT2000

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