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  1. #31
    Senior Member TiredFeet's Avatar
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    Quote Originally Posted by Schneiderlein View Post

    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.
    Do you have any calculations on what angles would be needed to increase the force from 200 to 800??

    MY girlfriend was curious some time back on the angles after I had been reading some the posts here and so we went to a park with a DIY hammock (all our hammocks have ridge lines) and some spare line. Strung the spare line tight between trees and then the DIY hammock suspension on top of the spare line, i.e., the tree huggers on top of the spare line. I pulled the DIY suspension moderately tight as I usually do, got in the hammock and she proceeded to make measurements and informed me that the angle was about 25 degrees ( maybe 26) and could I make it less. We figured that the only way to make it less was to pull the suspension tighter. I'm not Arnold Schwarzenegger, but I'm not the 90 lb weakling either ( 165 lbs and I can do 200 marine style pushups and have done so on my morning exercise regimen) , but I pulled the suspension as tight as I could manage. Plucked the suspension and got a nice note from the Spyderline. Gingerly got in the hammock. That was okay. Bounced around a little getting more energetic as my confidence increased. No problems from the suspension. I settled down and she proceeded to make her measurements again. Guess what? The smallest angle I could get with as much pull on tightening the suspension as I could muster was about 20 degrees. Maybe a degree or 2 less. Minimum would be 18 degrees.

    From that I very, very seriously doubt that there many people around that could get anywhere near 90 degrees. I doubt that there are any that could get close to 90 degrees with a loaded hammock, say 180 to 200 lbs, to seriously affect the safety margin on modern ropes.

    Oh the trees were slightly under 16' apart. Cannot remember the exact figures from the experiment, but I do remember approximately. The wider the separation, the further from 90 degrees you will end up.

    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.
    Agreed.

    I had a few more thoughts on why we decided long ago to always use a ridge line besides having a preset sag:

    1. chair height. We both like our hammocks hung so that it is about hip high when nobody is in it. That way when we grab the edge and turn around to sit down, the hammock settles down to about chair high which makes it very comfortable to just sit down.

      That also, makes getting out of the hammock very easy. Just like standing up from a chair.

      If the hammock is too high, we have to climb down out of it which isn't too bad. What is worse is having the hammock so low that we have to climb up out of it. If the hammock ends up much below chair height getting out involves more gymnastics and if a lot below chair high, we end up literally crawling out onto the ground and then standing up. Not comfortable.

      So, with a ridge line, maybe we just naturally like to hang higher than other people. Without a ridge line, we would be hanging even higher on the trees and may not even be able to reach high enough to do so. We could hang lower and be uncomfortable, but then why do that if the ridge line allows us to hang where we are comfortable?
    2. tree separation - About the minimum we can hang our DIY hammocks is about 14' and that is a real squeeze. We try for about 16' to 18', but have had to settle for up to 20' to 22' and a couple of times even more. Unfortunately the trees were not very accommodating when they seeded and didn't do so a uniform 17' apart.

      With a 16' separation, I have measured that we wrap the tree huggers over 5', about 5' 4" to 5' 6", above the ground. By standing back and eyeballing the hammock and where the hammock angle would cross the tree without the ridge line, it would do so above my head. Very close to 7'. At 18', it would be higher than I can reach. If now we had to settle for that 20' separation, we would be physically incapable of hanging the hammocks. We could never wrap the tree huggers high enough to keep the hammock off the ground without a ridge line. Even with the ridge line, the hammocks end up closer to the ground than we like.

      I notice on Youngblood's diagram, he projects the 30 deg suspension angle out to 18' and it is already up to 6' 8". I can reach high enough for that, but my girlfriend would need a ladder. I would be willing to bet that a lot of people would besides her.

      The ridge line lets us use wider separation and thus gives us a lot broader site selection. By limiting us to separations of say 14' to 18' max, we would have to choose less than desirable sites at times. Not often, but then why limit ourselves artificially when the ridge line frees us from that?


    Anyway. I like ridge lines and wouldn't have a hammock without one.
    Fortunately modern technology is such that we can have them with no problem.

    I am more than willing to use modern technology if it makes my life easier and better. Having said that I still keep my cell phone turned off 98% of the time

  2. #32
    Senior Member TiredFeet's Avatar
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    Quote Originally Posted by Youngblood View Post
    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.
    When you say
    you will have less drop when the hammock is weighted
    don't you really mean that you will end up higher from the ground? I fail to see how hanging higher will make the drop less. If I hang say 5' from the ground and drop say 12" when I get in the hammock. Won't the hammock drop the same 12" if I hang 6' on the same trees? I will end up 1' higher from the 6' hang than from the 5' hang, but the 12" drop will be the same either way.

    There are other reasons besides sag that we decided on ridge lines. See my other post that I was writing as you posted.

    As to whether or not we need a ridge line - NO. We don't need a car either. We could use a bicycle. Now try and talk people out of using their cars and trading them in for bicycles. Heck even the Chinese are abandoning their bicycles for cars as fast as they can . You would be even friendlier to the environment if you could do that rather than talking people out of using ridge lines.

    As far as discussing strictly from the viewpoint of the forces involved, yes I have already said that you are right about the forces involved. Now expand your view to the aspect of modern ropes. Modern technology is such that we can handle the forces involved with a ridge line. You keep writing about only one side of the discussion. Why should I limit my options and not take advantage of modern ropes which can very adequately handle the forces involved??? Sure I have to inspect the ropes periodically to make sure that they are not degraded, but then I would have to do that even if I didn't have a ridge line. So discarding the ridge line has not gained me anything and cost me the options that I have with a ridge line. You are saying the same thing as I should simply trade-in my car for a bicycle because the bicycle is lighter and puts less stress on the roads. If the roads are engineered to handle the 18 wheelers that are not going to be traded-in, what have I gained?

  3. #33
    Senior Member hangnout's Avatar
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    don't you really mean that you will end up higher from the ground? I fail to see how hanging higher will make the drop less. If I hang say 5' from the ground and drop say 12" when I get in the hammock. Won't the hammock drop the same 12" if I hang 6' on the same trees? I will end up 1' higher from the 6' hang than from the 5' hang, but the 12" drop will be the same either way.
    The hammock should not continue to rise higher from the ground when you tie higher up the tree to reduce the stress. Think more rope used on each end and a steeper angle to the hammock. Many times you can end up the same height from the ground but with very different forces on the suspension. With less stress it is easier to control where your hammock ends up under the tarp also.

  4. #34
    Senior Member TiredFeet's Avatar
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    Quote Originally Posted by HANGnOUT View Post
    The hammock should not continue to rise higher from the ground when you tie higher up the tree to reduce the stress. Think more rope used on each end and a steeper angle to the hammock. Many times you can end up the same height from the ground but with very different forces on the suspension. With less stress it is easier to control where your hammock ends up under the tarp also.
    Thanks - that's makes it clear. So you are actually do more than just hanging higher.

  5. #35
    Quote Originally Posted by TiredFeet View Post
    I fail to see how hanging higher will make the drop less. ?
    by hanging higher, he means making the suspension angle greater, which requires hanging higher on the tree, or finding closer trees.

    it's true about less drop though, imagine a single rope, tied between 2 trees and you crank it tight with a trucker's hitch, now pull down in the center of the line, it will flex like a bow string, it has to do with the increase in force due to the angle, similar to how decreasing the sag angle puts more force on the support ropes, more force = more stretch you are also pulling more perpendicularly to the line, which plays a big part i think as well.

    now imagine the same line between the trees, tie it with sag hanging down to the ground, it will stretch and drop much less, if you tie both ends to a single point, say an overhanging branch, both lines are hanging straight down, this will have the least stretch and drop of all.

    as for how the forces increase based on the angle, the designer of the hitchcraft mini device and some of the engineer folks here came to an agreement for a formula to calculate the forces, turns out to be less than was previously thought (at least by me) supposedly for a 30 deg. sag angle, the force on each support is equal to your bodyweight, if you weigh 200#, there would be 200# of force on each line/treesrtap/tree.

    it is somewhere in this thread: http://www.hammockforums.net/forum/s...ft+for+hammock
    Last edited by warbonnetguy; 02-01-2008 at 22:45.

  6. #36
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    Quote Originally Posted by TiredFeet View Post
    Do you have any calculations on what angles would be needed to increase the force from 200 to 800??

    MY girlfriend was curious some time back on the angles after I had been reading some the posts here and so we went to a park with a DIY hammock (all our hammocks have ridge lines) and some spare line. Strung the spare line tight between trees and then the DIY hammock suspension on top of the spare line, i.e., the tree huggers on top of the spare line. I pulled the DIY suspension moderately tight as I usually do, got in the hammock and she proceeded to make measurements and informed me that the angle was about 25 degrees ( maybe 26) and could I make it less. We figured that the only way to make it less was to pull the suspension tighter. I'm not Arnold Schwarzenegger, but I'm not the 90 lb weakling either ( 165 lbs and I can do 200 marine style pushups and have done so on my morning exercise regimen) , but I pulled the suspension as tight as I could manage. Plucked the suspension and got a nice note from the Spyderline. Gingerly got in the hammock. That was okay. Bounced around a little getting more energetic as my confidence increased. No problems from the suspension. I settled down and she proceeded to make her measurements again. Guess what? The smallest angle I could get with as much pull on tightening the suspension as I could muster was about 20 degrees. Maybe a degree or 2 less. Minimum would be 18 degrees.
    That's very interesting. The 4x increase in force was based on an angle of 7 degrees compared to 30 degrees, but I think you're right that it is probably not possible to achieve a low angle like that. For a 15 degree angle, the force is increased 2x, and for 20 degrees it's only 1.5x. Quite reassuring.

  7. #37
    tired feet, i see it was a diy hammock, was the fully tightened ridgeline nylon or spectra, spectra with a truckers hitch might get it a little tighter. were the huggers hh nylon ones? those could have given enough to effect things too. in other words, do you think different components would have enabeled you to get it to hang with even less sag angle, or do you really think that is as tight as you can get a hammock by hand? good experiment!

    how did she measure the angle percisely? i haven't figured an easy way to do it yet.

  8. #38
    Senior Member TiredFeet's Avatar
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    Quote Originally Posted by warbonnetguy View Post
    tired feet, i see it was a diy hammock, was the fully tightened ridgeline nylon or spectra, spectra with a truckers hitch might get it a little tighter. were the huggers hh nylon ones? those could have given enough to effect things too. in other words, do you think different components would have enabeled you to get it to hang with even less sag angle, or do you really think that is as tight as you can get a hammock by hand? good experiment!
    Used 2.8 mm Spyderline suspension, the ridge line was cryslaline (sp?), the smallest diameter, the tree huggers are polyester straps. That gives the minimum stretch I have been able to find - well practically none. I have now switched the Spyderline for the 3 mm Lash-It and get the same result for a lot less money.

    Used the system described elsewhere: hang suspension and ridge line and then hang the hammock from that line using the rings and stake toggles. Quick and and easy way to hang for us.

    I don't think that I could have gotten less sag with any other system. I can pull the suspension and ridge line alone a lot tighter than I can with the hammock hanging off it. Also, I used the modified Trucker's hitch the same guy described with the carabiner - that system is really nifty for hanging the hammock. The modified truckers hitch gives an advantage in pulling the line so you can pull much tighter if you want to. I use it because the advantage makes it easy to hold the line while wrapping the carabiner.

    Edit Note - I don't use the system to pull the suspension and ridge line really, really tight. I use the system because it is the easiest system I have tried for hanging the hammocks. I do pull tight, but not as tight as I did in the experiment. Just moderately so as I did initially in the experiment. Her measurements showed that with the moderate pull I normally use, we are using the range of angles that Youngblood likes even with using a ridge line.

    Quote Originally Posted by warbonnetguy View Post
    how did she measure the angle percisely? i haven't figured an easy way to do it yet.
    Yeah, she thought about that for a while to get a usable setup.

    She came up with two methods (she's an engineer so she's good at this):

    1. laser level - she has one of those self-leveling laser levels that projects crossed beams. Set it up on a tripod. Hang the hammock and then position the crossed beams for a reference system to measure from. You can set the crossed beams anywhere that is convenient to measure from.
    2. reference line - ran a Spyderline line from tree to tree. That gave her a reference line. She then measured out from the tree and then down to the suspension line, both when the hammock was empty and after I got in and settled down.


    Once she had the measurements, she used her handy-dandy calculator to compute the angles from the triangles she measured.

    She used method 2 in the park - simpler than carrying the tripod and laser level. She thought method 1 would be more accurate, but that that level of accuracy wasn't really needed for what we wanted. The angles within 2 or 3 degrees was adequate to satisfy our curiosity about the safety margins of the ropes we use. She was happy and that made me happy. We don't even think about the forces anymore since she made her measurements. These modern ropes made from the modern fibers have made life a lot easier for us hanging the hammocks.
    Last edited by TiredFeet; 02-03-2008 at 11:17.

  9. #39
    Senior Member Just Jeff's Avatar
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    Youngblood - good info. I never thought about the decreased angle causing the hammock to sink lower to the ground. I'll still use ridgelines b/c I like the consistency and b/c I hang things from it, but I'll probably start hanging higher on the tree now so I get a more consistent tarp-hammock spacing.

    Thanks for the info.
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