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  1. #11
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    Quote Originally Posted by GrizzlyAdams View Post
    Youngblood...each half foot is incremented 7 inches on each end maybe? In other words, for every 6" increase in span you make a mark 7" further down the suspension line?

    That I understand because it is just what I was saying earlier...and I think you mentioned it to me in a PM once...

    If you really and truly mean what you wrote as you wrote it, I don't get it.

    Grizz
    Grizz... you have two suspension lines so you increase it on both suspension lines. 7" on one plus 7" on the other equals 14" of total suspension line for every 12" increase in the span. There is a doubling effect in there with marking and centering, I have synchronized the length adjustments of the two suspension lines.
    Youngblood AT2000

  2. #12
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    Quote Originally Posted by TeeDee View Post
    Also, your rule of cos(31) ~ 6/7, is usable for a single sag angle. You than have only one thing that you can adjust to achieve your desired hammock height - how high you place the tie off points, i.e., the tree huggers. By limiting yourself this way means that where I go, you would have to pass by a LOT of otherwise suitable hang spots and spots that would be better than the ones you could use. I would guess that on the maintained trails in the US this is probably not a problem though.
    The sag angle can vary, the 31 degrees is a target used to set the geometry. You can leave the tie off height alone and adjust the suspension length to get the hammock body at an acceptable height above the terrain. If you do that and the sag angle is not within an acceptable range, then you can adjust the tie off height. Of course depending on your suspension system and how it is attached, adjusting the tie off height may be easier to adjust or the suspension length may be easier or they may be about the same.

    There are several levels to this issue. There is getting it in the ball park, so to speak, and there is getting it fine tuned, or just right. I'm under the impression that some folks routinely start off tying off the hammock on the low side and have a tough time getting things in the ball park. I suspect that a lot of those folks don't have a good understanding of the geometry, forces and stretch involved (because if they did they wouldn't do it that way), could care less about that, and may never understand that.
    Youngblood AT2000

  3. #13
    Senior Member headchange4u's Avatar
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    I had to read through TeeDee post a couple of times but I now see, with the help of Grizz's explanation, what he is doing and think it's going to be a great system to get a very consistent hang. I can't wait to get out and test the system. You really flatter me that I was part of the inspiration on putting this system together. I guess a blind squirrel will find a nut every once in a while.

    TeeDee,

    As far as measuring distance between trees, you may take a look at the laser measuring devices sold at home improvement stores like Home Depot or Lowes. I have one that pretty light. They are made for measuring rooms or other items around the home. You but the butt end of the device against one end of what you are measuring and the unit fires a laser at whatever you are measuring a distance away. Accurate to within a couple of inches per 50' I believe. I use the hiking pole/outstretched arms to measure the distance between trees all the time, and it works well for getting a general idea if my hammock setup will fit.
    “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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  4. #14
    GrizzlyAdams's Avatar
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    Quote Originally Posted by Youngblood View Post
    Grizz... you have two suspension lines so you increase it on both suspension lines. 7" on one plus 7" on the other equals 14" of total suspension line for every 12" increase in the span. There is a doubling effect in there with marking and centering, I have synchronized the length adjustments of the two suspension lines.
    Units always help. You're adding 7" per end per foot of _total_ additional span, whereas my units were 7" per end per foot of additional span _per end_.

    thanks

    Grizz

  5. #15
    Senior Member TiredFeet's Avatar
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    wrong conclusion

  6. #16
    Senior Member TeeDee's Avatar
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    Quote Originally Posted by Youngblood View Post
    The sag angle can vary, the 31 degrees is a target used to set the geometry. You can leave the tie off height alone and adjust the suspension length to get the hammock body at an acceptable height above the terrain. If you do that and the sag angle is not within an acceptable range, then you can adjust the tie off height. Of course depending on your suspension system and how it is attached, adjusting the tie off height may be easier to adjust or the suspension length may be easier or they may be about the same.

    There are several levels to this issue. There is getting it in the ball park, so to speak, and there is getting it fine tuned, or just right. I'm under the impression that some folks routinely start off tying off the hammock on the low side and have a tough time getting things in the ball park. I suspect that a lot of those folks don't have a good understanding of the geometry, forces and stretch involved (because if they did they wouldn't do it that way), could care less about that, and may never understand that.
    Okay - I see what you are doing. You want to get in the "ball park" as you say and then you adjust things from there. And yes that reduces the adjustments considerably. It is far better than just putting things on the trees and then guessing the adjustments to get near what you want which can take quite a while.

    Once you have the hang to the point that just small adjustments can be done, then it is a lot easier to see the adjustments to be made and to make them.

    What you are doing helps and helps a lot, but as you say it doesn't eliminate the adjustments.

    This is especially true since you have limited your "ball park" process to a single sag angle. Once there you then have to start adjusting both sag angle and tie off point height. That can still leave a lot of adjusting it would seem.

    What I wanted was a method to hang it - done.

    Accurately measuring span distance is essential to that.

    Also I wanted a method that would allow for longer spans than you seem to admit. 20' spans are not uncommon for me. At 17' to 20', the tie off point height can get too high if you limit yourself to 30 degree sag angle.

    I look at it that you have solved a particular case of the problem, the 30 degree sag angle. I needed the more general case of varying sag angle and tie off point height.

    I also wanted to eliminate the adjusting process. I have almost accomplished that in that the only adjusting I need with the hang rope measuring process is to sometimes move the tree huggers. Usually not.

    Measuring the span and then picking both sag angle and tie off point height insures that my hammock height is where I want it when finished.

    Also, as you pointed out, little to no stretch in the suspension is essential. Polyester webbing is then essential for a webbing system. The new high tech single or double braid ropes are ideal for this since the stretch is zero for all practical purposes. Especially if you use something like the Amsteel Blue or AS 78. The stretch is less than 1% for 30% of breaking strength (I think I remember that correctly). The dyneema I use is pretty good for that also, being slightly over 1% for 30% load.

    Quote Originally Posted by headchange4u View Post
    I had to read through TeeDee post a couple of times but I now see, with the help of Grizz's explanation, what he is doing and think it's going to be a great system to get a very consistent hang. I can't wait to get out and test the system. You really flatter me that I was part of the inspiration on putting this system together. I guess a blind squirrel will find a nut every once in a while.
    Don't underestimate what you did. A lot of times the simplest seeming idea makes a huge difference.

    Quote Originally Posted by headchange4u View Post
    TeeDee,

    As far as measuring distance between trees, you may take a look at the laser measuring devices sold at home improvement stores like Home Depot or Lowes. I have one that pretty light. They are made for measuring rooms or other items around the home. You but the butt end of the device against one end of what you are measuring and the unit fires a laser at whatever you are measuring a distance away. Accurate to within a couple of inches per 50' I believe. I use the hiking pole/outstretched arms to measure the distance between trees all the time, and it works well for getting a general idea if my hammock setup will fit.
    Thanks - I'll have to check them out. Didn't know anything about those.

  7. #17
    GrizzlyAdams's Avatar
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    low tech range finder

    so last time I was in Home Depot they had piles of low tech range finders, in bright pink, yellow, or green. "Twisted" or "Braided".

    Instructions said you needed only to put knots in, spaced every 6". Also said it was dual purpose, you could use it in masonry, pulled tight to set a straight line.

    I didn't understand that part.



    Grizz
    Last edited by GrizzlyAdams; 08-07-2008 at 08:32.

  8. #18
    GrizzlyAdams's Avatar
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    how low can you go???

    I toyed a bit with a one-line suspension last summer, and in the end abandoned it because (a) I found it more convenient to to have a ring separate the suspension lines from the ridgeline (so I could hang the hammock from it, and make the ridgeline easily adjustable), and (b) I was using cord for the ridgeline that was much stronger---hence much heavier---than needed for the forces that would be placed on it. At the time I was using Spyderline 3.8mm. Don't need that for a ridgeline.

    So this Marlin spike hitch business opens the way for easy ridgeline adjustment with a convenient hang point (I finally this morning read what TeeDee was saying about the lark's head on the toggle. Since I've not been using the Marlin spike hitch to hang the hammock itself I've been skipping over that bit. Now I just need a source for the high test toggles needed on the suspension rope.)

    The point remains though, that Amsteel blue or Vectran 12 or Spyderline is still way overkill strength-wise for what is needed on the ridgeline.

    Hence my modest proposal.

    Decide on some minimum length ridgeline. Using TeeDee's method you do that when choosing marks to calibrate for the Marlin spike hitches. Take a piece of strong-enough-for-ridgeline cord, e.g. LashIt (thx TiredFeet!) at that length. Attach suspension cord and tie to the ridgeline at both ends using double sheetbend. You'll still attach the Marlin spike hitches on the suspension cord, and only ridgeline-scale force will be on the lighter cord. Everything else in the system works as before, all your marks will be on the suspension line, not the ridgeline.

    Grizz

  9. #19
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    Quote Originally Posted by TeeDee View Post
    Also I wanted a method that would allow for longer spans than you seem to admit. 20' spans are not uncommon for me. At 17' to 20', the tie off point height can get too high if you limit yourself to 30 degree sag angle.

    I look at it that you have solved a particular case of the problem, the 30 degree sag angle. I needed the more general case of varying sag angle and tie off point height.
    You always have limits. Mine are 12 feet for minimum span because of the tarp and 18 feet for maximum span because, as you point out, that is the height limit that I can reach for the 30 degree sag without a structural ridgeline. I also have limits on tree diameter. To borrow a line from a Clint Eastwood movie, "A man has to know his limitations".

    What maximum span and tree diameter do you pack for? (You probably realize that what I am getting at is having suspension line, tree huggers, whatever, for unnecessarily long spans or for the largest diameter trees in the forest go against the pack light philosophy where you more carefully consider the tradeoffs and what your options are... not that there is anything wrong with doing otherwise.)
    Youngblood AT2000

  10. #20
    Senior Member TeeDee's Avatar
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    Quote Originally Posted by GrizzlyAdams View Post
    I toyed a bit with a one-line suspension last summer, and in the end abandoned it because (a) I found it more convenient to to have a ring separate the suspension lines from the ridgeline (so I could hang the hammock from it, and make the ridgeline easily adjustable), and (b) I was using cord for the ridgeline that was much stronger---hence much heavier---than needed for the forces that would be placed on it. At the time I was using Spyderline 3.8mm. Don't need that for a ridgeline.

    So this Marlin spike hitch business opens the way for easy ridgeline adjustment with a convenient hang point (I finally this morning read what TeeDee was saying about the lark's head on the toggle. Since I've not been using the Marlin spike hitch to hang the hammock itself I've been skipping over that bit. Now I just need a source for the high test toggles needed on the suspension rope.)

    The point remains though, that Amsteel blue or Vectran 12 or Spyderline is still way overkill strength-wise for what is needed on the ridgeline.

    Hence my modest proposal.

    Decide on some minimum length ridgeline. Using TeeDee's method you do that when choosing marks to calibrate for the Marlin spike hitches. Take a piece of strong-enough-for-ridgeline cord, e.g. LashIt (thx TiredFeet!) at that length. Attach suspension cord and tie to the ridgeline at both ends using double sheetbend. You'll still attach the Marlin spike hitches on the suspension cord, and only ridgeline-scale force will be on the lighter cord. Everything else in the system works as before, all your marks will be on the suspension line, not the ridgeline.

    Grizz

    I knew that others could improve on the system.

    Thanks.

    For the toggles another way to go can be found at Lowes or Home depot. I tried these before I found the stainless tubing. At Lowes they sell steel pins, I forget the exact name, but I call them clevis pins, I'm pretty sure they call them something else. They are a steel pin with a hole on one end with a split keychain ring through the hole. The ones I used are 1/4" OD and about 3.5" long. I cut into 2 1.5" lengths and drilled a hole in the end of one and used the hole they already had in the other. I polished them as I mentioned in the article. 2 pins (they sell them 2 in a plastic bag) yielded 4 toggles.

    They worked great, but I finally opted for the tubing since it is lighter - now I'm beginning to sound like a SUL person - nothing wrong with that I guess. I think the pn toggles cam out at 0.16 oz vs the tubing at 0.10 oz

    I'm swinging back and forth on the laser rangefinder and my optical rangefinder and neither.

    I LOVE gadgets, but would rather not use them if possible.

    The rangefinder (laser or optical) has a definite appeal - measuring span distance so that I then know tie off point height and necessary sag angle before I do any set-up.

    Have to balance that against the simplicity of using the hang rope to measure. An all-in-one solution. Nothing extra. Using the hang rope to measure is easy and really pretty quick and adequate accuracy has been designed into it's construction.

    I'm having gearhead withdrawl symptoms and I haven't really got the gear yet - well I'll have to ameliorate the symptoms somewhat and use the optical rangefinder at least to test.

    Yes using the Lash-It for the ridge line portion of the hang rope is definitely doable. I'd probably do it also except that the 3 mm dyneema my cousin picked up on ebay is so very light (He has informed me that it is Lash-It also, the 3 mm diameter version. )

    And yes hanging from the toggles is really easy and convenient. I'm just sorry it took me so long to drop the hang knots and just use them.

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