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  1. #1
    GrizzlyAdams's Avatar
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    Hammock body guylines

    Quote Originally Posted by warbonnetguy View Post
    this is off topic, but i've never created a new thread before a couldn't figure out how to do it.

    anyways, i was wondering what hammocks besides a hh, have guylines on the sides that pull apart the hammock body/netting? guylines for the fly don't count...Brandon
    Created the thread so that any discussion on this can be properly found.

    I think an observation made in the now-dormant thread on patents has some bearing here.

    Quote Originally Posted by ac33 View Post
    this book is from 1904 ...
    Link to that posting to see a picture of a page from a book describing a "Hammock Sleeping Tent". The page includes the text
    The tent is suspended by the ridge from a heavy rope supported on trees or posts. It is kept taut on the side by tent ropes attached to stakes driven in the ground.
    There is no differential between hammock body and fly here. The guylines are pulling apart the sides of the body to keep it taut.

    These guylines are not placed asymmetrically however. A modern hammock sold with symmetrically placed guylines on its body ought to be outside the domain of a patent that specifically claims asymmetric placement as a protected invention. In an earlier posting I pointed the Hennessey patent on tie-outs

    Quote Originally Posted by GrizzlyAdams View Post
    ... I mention that the Hennessey patent claims appear to include the pull-out ties on the sides. Claim 1 of US Patent 6865757
    (see http://www.patentstorm.us/patents/6865757-claims.html )
    Read the claim and you see that it specifically covers tie-outs that create an asymmetric tension axis. Looks like the asymmetry of the warbonnet's tie-outs are key to its making room at the foot and head, and fit the description.

    hat-tip to ac33 for finding the 1904 book!

    See also the image of the S3 "with fly" attached

    http://www.backpacking.net/gear-reviews/sss/

    It has, on close inspection a line visible which I don't think is a
    fly's guyline. It's the dark one at about 7 o'clock from the tent body.
    The guyline for the fly corner closest to the observer is barely visible.
    Text describing the shelter describes the fly as having 6 guylines, so the
    one at 7 o'clock is something else. Text description on Weather Resistence says
    "The sides of the fly, as well as the hammock can be staked down to provide additional stability".


    Grizz
    Last edited by GrizzlyAdams; 06-11-2007 at 08:32. Reason: description of another shelter; then correct comment on warbonnet

  2. #2
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    Other than the Warbonnet ones, I have not came across any.

    I think we should be careful to keep this on topic and not turn it into another patient or hh complaining thread.
    Is that too much to ask? Girls with frikkin' lasers on their heads?
    The hanger formly known as "hammock engineer".

  3. #3
    GrizzlyAdams's Avatar
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    impact of guylines

    My experience with camping hammocks is limited entirely to the HH products. I've always staked out the body guylines. My impression is that they effectively work more to pull the upper portion of the body away and create more space above me, not so much create a tension axis on the diagonal.

    Am I just guying these out incorrectly and missing the point, or do they perceptively help in flattening the hammock floor along the diagonal? In backyard experiments where I don't guy them out, I can't say that I can tell the difference.

    Grizz
    Last edited by GrizzlyAdams; 06-09-2007 at 06:51.

  4. #4
    Senior Member headchange4u's Avatar
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    I agree with HE. I have never seen another hammock that uses any kind of line to pull the sides of the hammock out besides the Warbonnet hammocks and HH. The Claytor hammocks do have the ability to use a spreader bar that helps to open up the hammock.

    I don't think that being able to tie out a HH or a Warbonnet in any way effects how the hammocks lay. I think they are simply there to open the hammock up and give you more room inside. That's why I put them on my hammocks.
    “Light thinks it travels faster than anything but it is wrong. No matter how fast light travels, it finds the darkness has always got there first, and is waiting for it." -Terry Pratchett



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  5. #5
    GrizzlyAdams's Avatar
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    flatness of the lay

    Morning runs are fine times to think about hammock geometry.

    Forgive me for belaboring what is obvious to the old hands. I'm still playing catch-up.

    I imagine a hammock as pictured below.



    I'm the fat line off-center in the middle. I'm lying an a dashed diagonal line. The flatness of my lay depends on the vertical distance between my centerpoint c, and the highest point, which will be one of the endpoints. That distance depends on a number of things. First, on the length of the fabric along the dashed line. For a given degree of being off-center, that is fixed. Second, the depth to which c can go depends on the distance between a and e, and my weight. That's also fixed, if using a structural ridgeline, and I lay off the evening snacks. Third, the flatness depends on the vertical distance between the hammock endpoints and the endpoints of my line of tension, e.g., between a and b. That distance is affected by the distance between a and e also, by the length of fabric from b to d, and by my weight. Finally, the flatness is affected by the vertical distance between my tension endpoints (e.g., b and d) and the endpoints of my body.

    So it seems to me that if a body side guyline is going to affect my lay along this axis, it's only option is to pull the height of b and d down. Furthermore, it is not enough to just lower the height of b and d. By doing that you need also to lower the height of my feet and head.

    The shockcord used on my tieouts is pretty thin, and doesn't exert much force. For it to exert more downward force on points b and d to lower my head and feet than do the weight of these appendages----I'm not seeing it. Might work if I used real guyline cord, but I'm not sure that the guyline tab on the body is engineered for that kind of tug.

    I can see though that a flatter lay could be created as compared with this if more fabric is introduced along the tension axis, as might be done when the hammock is cut and wrapped.


    Grizz
    Last edited by GrizzlyAdams; 06-09-2007 at 09:55. Reason: every complete sentence needs a verb

  6. #6
    thanks guys, i just couldn't remember if some of those less popular brands did or not and i figured there might be a hammock out there that i had never heard of that did tension the body.

    as for affecting the lay, side tension pts can NOT give you a better/flatter lay than the naked hammock body would allow, however if the pts. are placed in the wrong spots, this "potential that the bed fabric naturally has because of it's dimensions", can be reduced. this is why a hh only allows you to lay on one diagonal, the tension points are in the wrong place if you lay the other way. if you simply pulled harder, nothing would happen until the hammock's edge finally tore. you can see this if you pull along the edges of an eno style hammock, the length of the hammocks edge is fixed, the slight pull of shock cord or your pinky finger would be enough to pull out all the slack and slightly load the edge. beyond this, the nylon would stretch a little and if pulled hard enough would fail, but the shape, and thus the lie, would remain constant throughout, to do anything you have to change the dimensions of the fabric...Brandon

  7. #7
    Senior Member TeeDee's Avatar
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    Quote Originally Posted by GrizzlyAdams View Post
    Morning runs are fine times to think about hammock geometry.

    Forgive me for belaboring what is obvious to the old hands. I'm still playing catch-up.

    I imagine a hammock as pictured below.



    I'm the fat line off-center in the middle. I'm lying an a dashed diagonal line. The flatness of my lay depends on the vertical distance between my centerpoint c, and the highest point, which will be one of the endpoints. That distance depends on a number of things. First, on the length of the fabric along the dashed line. For a given degree of being off-center, that is fixed. Second, the depth to which c can go depends on the distance between a and e, and my weight. That's also fixed, if using a structural ridgeline, and I lay off the evening snacks. Third, the flatness depends on the vertical distance between the hammock endpoints and the endpoints of my line of tension, e.g., between a and b. That distance is affected by the distance between a and e also, by the length of fabric from b to d, and by my weight. Finally, the flatness is affected by the vertical distance between my tension endpoints (e.g., b and d) and the endpoints of my body.

    So it seems to me that if a body side guyline is going to affect my lay along this axis, it's only option is to pull the height of b and d down. Furthermore, it is not enough to just lower the height of b and d. By doing that you need also to lower the height of my feet and head.

    The shockcord used on my tieouts is pretty thin, and doesn't exert much force. For it to exert more downward force on points b and d to lower my head and feet than do the weight of these appendages----I'm not seeing it. Might work if I used real guyline cord, but I'm not sure that the guyline tab on the body is engineered for that kind of tug.

    I can see though that a flatter lay could be created as compared with this if more fabric is introduced along the tension axis, as might be done when the hammock is cut and wrapped.


    Grizz
    My limited experience leads me to believe that the biggest contributor to the ability to lay comfortably on the diagonal is sag - the more sag the more diagonal you can get comfortably. As a corollary to that, the longer the hammock, the more sag you can comfortably induce. You can hang a very short hammock with a lot of sag, but you are going to be very cramped.

    Now the above is strictly for hammocks that gather the hammock ends and tie them off, i.e., hammocks in which the length of the hammock is greater than the width. Most, if not all commercial and DIY hammock are in this category.

    Going to the opposite extreme where the width of the hammock is far greater than the length we have:

    the case of the 1904 book and this hammock and the JRB hammock (all three are essentially the same and intentionally or unintentionally the JRB hammock is patterned after the second hammock to which a link is provided), the ends are not gathered. Rather in all of those cases the ends are spread out and the hammock supported along the entire spread out end. The length of the hammock is then shortened to just a little more than the width of the body. Also, in those hammocks the less sag the better - less shoulder squeeze.

    In all of the three hammocks above, you are laying totally on the diagonal, i.e., at 90 deg to the hammock axis.
    Last edited by TeeDee; 06-09-2007 at 14:38.

  8. #8
    Senior Member TeeDee's Avatar
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    Quote Originally Posted by GrizzlyAdams View Post
    My experience with camping hammocks is limited entirely to the HH products. I've always staked out the body guylines. My impression is that they effectively work more to pull the upper portion of the body away and create more space above me, not so much create a tension axis on the diagonal.

    Am I just guying these out incorrectly and missing the point, or do they perceptively help in flattening the hammock floor along the diagonal? In backyard experiments where I don't guy them out, I can't say that I can tell the difference.

    Grizz
    In my experience with HH, the side tie outs when tied out or left untied have no effect on how I lay in the hammock. When tied out, they open the hammock out so that the side edges are held further away from me. Conversely, if I take the side tie outs and tie them to the ridgeline, they do affect the how I can lay in the hammock (much less diagonal) and tend to fold the sides edges close and over me.

  9. #9
    GrizzlyAdams's Avatar
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    Quote Originally Posted by TeeDee View Post
    Going to the opposite extreme where the width of the hammock is far greater than the length we have:

    the case of the 1904 book and this hammock and the JRB hammock (all three are essentially the same and intentionally or unintentionally the JRB hammock is patterned after the second hammock to which a link is provided), the ends are not gathered. Rather in all of those cases the ends are spread out and the hammock supported along the entire spread out end. The length of the hammock is then shortened to just a little more than the width of the body. Also, in those hammocks the less sag the better - less shoulder squeeze.

    In all of the three hammocks above, you are laying totally on the diagonal, i.e., at 90 deg to the hammock axis.
    that's an interesting way to look at it.

    I'm oddly reminded of the joke about responding to a wrong number :
    You've reached an imaginary number. Please rotate your telephone 90 degrees, and try again.

    Grizz

  10. #10
    Senior Member blackbishop351's Avatar
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    Like others have mentioned, I've seen no difference in my HH with or without the side elastics tied. NO difference. In fact, I removed them from my ULB altogether when I was still using it, just because they were a nuisance and IMO completely useless.
    "Physics is the only true science. All else is stamp collecting." - J. J. Thompson

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