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.
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.
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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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.
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.
Last edited by GrizzlyAdams; 08-07-2008 at 09:32.
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.
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.)
I knew that others could improve on the system.
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.