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  1. #1
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    Bridge Hammock Design Questions

    After looking at every manufacturer on the spreadsheet list here and looking at every hammock each of them makes, I've realized that the only way I'm going to get EXACTLY what I want is to make it myself.

    Good thing I'm a skilled seamstress and designer, now all I have to do is learn to call my sewing machines 'thread injectors' ---took me a while to figure that one out...

    Now comes a couple of questions about the design of a bridge hammock.

    All the DIY hammocks I've seen have the extender bars/spreaders way above the hammock 'shelf'. Why - what advantages are there to having them way above?

    I looked at the Blue Ridge hammock (Lawson) and the spreader bars are at the same level as the hammock shelf. It seems to give the flattest lay of them all.

    Does it make it too tippy? And would side tieouts not compensate for that?
    It would certainly put the bars lower so that there wasn't a problem with them clashing with the tarp which seems to be a common problem.

    The BR also has multiple lines rather than just one at each corner. What does this do for the hammock lie and why are all the DIY's I see not doing that?

    While I never expect to be an UL'r, I want to keep my weight down, after all I have to carry it! OTOH, I want the most comfortable sleep I can get and am willing to do what it takes to get there!

    Discuss design concepts with me!!

    Oh, and I went back 40 pages in the DIY section looking for answers!

  2. #2
    jbrianb's Avatar
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    There are others with more bridge knowledge than I have, so this is a simplified answer: Bridge hammocks work like, well, suspension bridges. The hammock hangs from suspension straps on the side of the hammock which connect to spreader bars on the ends. This gives you a "ditch" to lie in that you won't roll out of and the hammock won't flip. Spreader bars level with your hammock take away that trough and make the hammock a lot more tippy. Side tie outs wouldn't solve this problem and would, I'd expect, simply pull the sides down making it harder to find a good spot to lie in the center without rolling out of the thing.

    For comfort and for heavy use, I think you'd want the bars-above-the-hammock design that Warbonnet and JacksRBetter and others use.

    I welcome corrections from GrizzlyAdams and others who are much more knowledgable about bridge hammocks.
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  3. #3
    BrianWillan's Avatar
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    Quote Originally Posted by The Old Boot View Post

    Discuss design concepts with me!!

    Oh, and I went back 40 pages in the DIY section looking for answers!
    The Old Boot

    If you look in the DIY section there are a series of stickies that show up at the top of the listings. Four of them are by GrizzlyAdams on the construction of his GrizzBridge Hammock. I suggestion you watch his videos as he goes into great detail on how that bridge hammock is constructed.

    Also if you look up threads by TeeDee he has one on bridge design principles from 2009, if I recall correctly.

    I have recently made 2 bridge hammocks based on the videos from Grizzly Adams. So if you have specific questions, ask away. I don't profess to be an expert on the subject, however I will help out any way I can.

    Cheers

    Brian
    Good judgment comes from experience, and often experience comes from bad judgment. - Unknown

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  4. #4
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    Quote Originally Posted by BrianWillan View Post
    The Old Boot

    If you look in the DIY section there are a series of stickies that show up at the top of the listings. Four of them are by GrizzlyAdams on the construction of his GrizzBridge Hammock. I suggestion you watch his videos as he goes into great detail on how that bridge hammock is constructed.

    Also if you look up threads by TeeDee he has one on bridge design principles from 2009, if I recall correctly.

    I have recently made 2 bridge hammocks based on the videos from Grizzly Adams. So if you have specific questions, ask away. I don't profess to be an expert on the subject, however I will help out any way I can.

    Cheers

    Brian
    Oh, I've already watched all of Grizz's video's and I owe him a big thank you cause he's saved me countless hours of design time and shown me a few shortcuts that I would have thought of in hindsight.

    Haven't found TeeDee's threads yet, will go find them now!

    My absolute favourite question is 'WHY', not how, not when but Why...

    Comes from having an engineer for a father I guess.

    Why is it done this way and why can't it be done that way?

  5. #5
    Member JDShearer's Avatar
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    http://www.hammockforums.net/forum/s...ead.php?t=8537
    That's the most in-depth discussion I've seen. Great info there. Good luck!

  6. #6
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    Quote Originally Posted by JDShearer View Post
    http://www.hammockforums.net/forum/s...ead.php?t=8537
    That's the most in-depth discussion I've seen. Great info there. Good luck!
    Thanks for the link - I've got it bookmarked for repeated reading so I can make little diagrams of axis's, perpendiculars and weight stresses.

    But ya know, I still don't know why y'all are putting the spreader bars so far above the hammock! And I don't think it's to do with me being blonde!

  7. #7
    Senior Member mattyg's Avatar
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    Have you ever seen a suspension bridge the tops of the towers are the spreader bars. If you put them at the bottom it doesnt suspend and puts alot of force on the poles the lawson hammock is more like a pawleys island spreader bar hammock for your back yard than like the bridge hammocks you see here.

  8. #8
    krugd's Avatar
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    Quote Originally Posted by The Old Boot View Post
    Now comes a couple of questions about the design of a bridge hammock.

    All the DIY hammocks I've seen have the extender bars/spreaders way above the hammock 'shelf'. Why - what advantages are there to having them way above?

    I looked at the Blue Ridge hammock (Lawson) and the spreader bars are at the same level as the hammock shelf. It seems to give the flattest lay of them all.

    Does it make it too tippy? And would side tieouts not compensate for that?
    It would certainly put the bars lower so that there wasn't a problem with them clashing with the tarp which seems to be a common problem.

    The BR also has multiple lines rather than just one at each corner. What does this do for the hammock lie and why are all the DIY's I see not doing that?

    While I never expect to be an UL'r, I want to keep my weight down, after all I have to carry it! OTOH, I want the most comfortable sleep I can get and am willing to do what it takes to get there!

    Discuss design concepts with me!!

    Oh, and I went back 40 pages in the DIY section looking for answers!
    I think this was pretty much answered above, but yes the hammock would become quite tippy with the suspension bars lowered to the height of the hammock "shelf". I don't think that such a hammock could be called a 'bridge' as the design of a bridge hammock requires supports (the spreader bars) that hold a parabolic (or catenary) suspension cable (the webbing or rope in the edge) that supports the hammock shelf. Because of the parabolic cut in the edge of the hammock the bed of the hammock remains relatively flat - as in a suspension bridge. With your design you would seem to lose the ability to have the flat lie that the bridge is know for.
    --Don---

    May your trails be crooked, winding, lonesome, dangerous, leading to the most amazing view. May your mountains rise into and above the clouds. - Ed Abbey

  9. #9
    WV's Avatar
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    BER has put some thought into bridge hammock design as well. Here are links to four of his threads over a period of 16 months. He tried some commercial hammocks and built four of his own in that time.

    Examination of the Eureka Chrysalis

    The Cloud

    The Cirrus

    DIY #4 Bridge

  10. #10
    stevebo's Avatar
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    With the spreader bars, the width of the bar makes a huge difference in stability. A wider spreader bar will give you a flatter, wider lay in the hammock-with less shoulder squeeze (because its spread out more )--------but the wider the spreader bar, the more unstable the hammock will be. With my grizz bridge , I experimented with several lengths of spreader bars until I found a compromise between stability and a flatter, wider lay. Like everything else on the forum, you will have to play around with it , tweek it until its where you want it to be!
    “The two most common elements in the universe are hydrogen and stupidity.”
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