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  1. #31
    GrizzlyAdams's Avatar
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    Quote Originally Posted by bmike View Post
    been thinking on this.

    i think for better results i'm going to run the tarp line through my ring buckles (without threading) then along the suspension line to the prussik hook (stock HH). pull everything tight as usual, and when I get in, the sag in the hammock will pull the tarp tighter, as the hammock drops, the length of the tarp line needs to get longer... pulling it tight. might work slick with a tensioner on there too.

    this doesn't do much for keeping the tarp tight to the hammock... so for coverage you'll want a larger tarp - but this should tighten things up as you sag. tensioners on the land lines will help too.

    but, this is all moot if one ties to the trees first, gets a nice tight tarp with some tensioners for rain / dew...
    Sitting in a hotel room hundreds of miles from home it is a bit frustrating not to be able to pop out into the yard and try this stuff out.

    If I understand the scheme above, the arrangement is illustrated by the attachment, yellow lines being the tarp lines.

    If that's true, then the only difference between this and tieing the tarp to the prussik lines is that the tarp is positioned lower---it is equivalent to tieing off the tarp lines to the rings. The tension on the tarp line will decrease when you get in, just as it does if you use the prussiks w/o rings.

    Now pre-tensioning can help as BillyBob pointed out after reading the instruction manual, and having the tarp lower may be a good thing. But I don't think this will work in the same way as the original idea, which will I'm pretty sure tighten the tarp line.

    time for my complimentary bowl of cheerios...

    Grizz
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    Last edited by GrizzlyAdams; 11-02-2007 at 08:53. Reason: BillyBob remote editing...these aren't haggis inspired cheerios

  2. #32
    BillyBob58's Avatar
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    Quote Originally Posted by GrizzlyAdams View Post
    Sitting in a hotel room hundreds of miles from home it is a bit frustrating not to be able to pop out into the yard and try this stuff out.

    If I understand the scheme above, the arrangement is illustrated by the attachment, yellow lines being the tarp lines.

    If that's true, then the only difference between this and tieing the tarp to the prussik lines is that the tarp is positioned lower---it is equivalent to tieing off the tarp lines to the rings. The tension on the tarp line will decrease when you get in, just as it does if you use the prussiks w/o rings.

    Now pre-tensioning can help as BillyBob pointed out after reading the instruction manual, and having the tarp lower may be a good thing. But I don't think this will work in the same way as the original idea, which will I'm pretty sure tighten the tarp line.

    time for my complimentary bowel of cheerios...

    Grizz
    Griz, we are all hoping you meant "bowl" of Cheerios!


    I've been having trouble understanding how this will not have more or less the same effect as tieing to the HH prussick sliders as in the original design. In both cases, it seems, as the hammock heads south, the tarp goes with it. With the advantage that the hammock stays close to the tarp ridge for more rain protection. With the disadvantage ( in both cases?) that the tarp gets closer to the ground stakes and thus loosens up.

    But I am probably missing something, and I just need to get out there and try it out. Anybody tried it yet?

  3. #33
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    The original suggestion is quite different than the one dGrizzz is talking about above.

    In the original suggestion as the hammock lowers it pulls line from the tarp tieout. So as it lowers the tarp it also tightens the tension along the tarp ridgeline as the triangles that are created require more line length than the straight line they were in when tied.

    I'll try to get to it tonight and take some pics...
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  4. #34
    Bug-Bait's Avatar
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    Don't know whether this has already been discussed and/or whether it should be a separate thread...but, does anyone attach a length of thin bungee type cord to their tarp tie downs? If pulled tight to the stakes, it might help take up any slack that occurs when the hammock pulls the tarp down. Just a thought.

  5. #35
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    Called tensioners, and they're made a few different ways. you can check here for one way... with links to a second...

    Or if you dig about you'll find still others on the forums.
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  6. #36
    Member bmike's Avatar
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    Quote Originally Posted by Rapt View Post
    The original suggestion is quite different than the one dGrizzz is talking about above.

    In the original suggestion as the hammock lowers it pulls line from the tarp tieout. So as it lowers the tarp it also tightens the tension along the tarp ridgeline as the triangles that are created require more line length than the straight line they were in when tied.

    I'll try to get to it tonight and take some pics...
    exactly, in theory.
    i even threw it into an FEA program last night - the additional cords that tie the tarp to the hammock susp. line do go into tension as the triangle opens ip - so they should pull the tarp a bit tighter.

    ...but... if this were a truss, the tarp theoretically becomes a compression member (a small one, in this case with fixed points holding things up). this is what happens in the normal setup - but without tensioners there is no way to tighten the tarp. (if the tarp were rigid enough it would keep the hammock from sagging when you got in)

    theoretically with the proposed setup the tension added to the tarp line might overcome the 'compression' along the tarp ridgeline when you get in the hammock to overcome the sag. angle of attachment and length of cord probably play into how successful this could be.

    i don't have values programmed for spectra or lines, or silnyl, so i modeled it using steel pipe and applied a large load to get the deflection moving in the right direction.

    can you tell i was yak shaving last night and didn't want to work?

  7. #37
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    Quote Originally Posted by bmike View Post
    exactly, in theory.
    i even threw it into an FEA program last night - the additional cords that tie the tarp to the hammock susp. line do go into tension as the triangle opens ip - so they should pull the tarp a bit tighter.

    theoretically with the proposed setup the tension added to the tarp line might overcome the 'compression' along the tarp ridgeline when you get in the hammock to overcome the sag. angle of attachment and length of cord probably play into how successful this could be.
    Definitely plays into it, especially if you think of it all starting at full tension/zero sag... Consider the following situations.. 1)Tarp line goes from tree to tarp then back towards the tree a short distance before attaching to the hammock suspension line... 2) Tarp line goes from tree to tarp then dies to hammock suspension line at the nearest adjacent point... 3)Tarp line runs from tree to tarp then continues a short distance away from the tree before attaching to the hammock suspension line.

    In case 1)The short line back introduces some extra slack that actually LOOSENS the tarp in the initial phases of sag, until the vertical sag distance at that point exceeds the length of the short line.

    In case 2) Any sag of the hammock immediately tensions the tarp line as the sum of the two sides of the triangle is longer than the original length. And can put considerable tension on the tarp.

    In case 3) The line tensions the tarp more gradually as the portion from the tarp to the suspension gets drawn down closer and closer to perpendicular to the suspension line. Once that point is reached it becomes maximal for increase in tension with increasing sag.

    See attached pdf for illustration of before and after.
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    Last edited by Rapt; 11-02-2007 at 10:46.
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  8. #38
    Senior Member Just Jeff's Avatar
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    If the tarp is connected to the hammock supports, it does not tension when occupied. It does the opposite - the points where the tarp are connected get closer together in the horizontal plane, creating sag in the tarp.

    Another thing I've done is run the hammock support through the MacCat D-rings, like you're proposing. Then I ran a tensioner from those D-rings to a higher point on the hammock support to keep the tarp tensioned all the time. It worked ok. I found it was more complication than it was worth and I lost the ability to change the tarp's height or position with the weather...and more importantly, I could no longer set up the tarp first in rainy weather, then unpack under a dry tarp to set up the hammock. Or to set up the hammock with no tarp at all. That's the main reason I gave up the system.

    In the end, I decided to follow the KISS principle - store the tarp on the outside of my pack for quick access in bad weather and to let it dry, then set it up separately and only when needed. But that's just what works for me based on my style - I certainly think the experiments were worth the time and effort, though.

    Be sure to post pics of what you come up with.
    “Republics are created by the virtue, public spirit, and intelligence of the citizens. They fall when the wise are banished from the public councils because they dare to be honest, and the profligate are rewarded because they flatter the people, in order to betray them.” ~Judge Joseph Story

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  9. #39
    GrizzlyAdams's Avatar
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    tarp line geometry

    Quote Originally Posted by Just Jeff View Post
    If the tarp is connected to the hammock supports, it does not tension when occupied. It does the opposite - the points where the tarp are connected get closer together in the horizontal plane, creating sag in the tarp.
    I would amend the above to say
    If the tarp is connected only to the hammock supports, it does not tension when occupied.
    If the tarp ends are attached to the tree, and a connection is made between the tarp line and the suspension, the effect when the hammock is occupied is the same as if you grabbed the tarp line at two points and pulled it down. The distance a given length of tarp line now travels between its two tree connection points gets longer, so the tarp tightens up. The same is true if the tarp line goes from the tarp, to the tree, back to the tarp, and then down to the suspension line (the original proposal). Connecting to the tree gives the tarp line the outside frame of reference needed to avoid the sag.

    Indeed I'm more concerned about pulling the tarp too tightly this way than I am that it sags.

    Be sure to post pics of what you come up with.
    Just part of drill around here sir A picture is worth a thousand words. Some of give you the thousand words too, for free!

    Grizz

  10. #40
    Senior Member Just Jeff's Avatar
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    True statements, Grizz - I agree.
    “Republics are created by the virtue, public spirit, and intelligence of the citizens. They fall when the wise are banished from the public councils because they dare to be honest, and the profligate are rewarded because they flatter the people, in order to betray them.” ~Judge Joseph Story

    - My site: http://www.tothewoods.net/
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    IMPOSSIBLE JUST TAKES LONGER

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