This is the discussion thread for the Hammock Hanging Method - Addendum.
This is the discussion thread for the Hammock Hanging Method - Addendum.
“I think that when the lies are all told and forgot the truth will be there yet. It dont move about from place to place and it dont change from time to time. You cant corrupt it any more than you can salt salt.” - Cormac McCarthy
I'm sorta busy right now, but I will check back in daily.
If anybody has ideas for improving the hang rope method of hanging a hammock, they will be very welcome. There are ALWAYS improvements that can be made.
Any changes will also be seriously considered.
Also, if anybody doesn't have access to AWK, I will run the programs with your parameters (ridge line length and max tree separation) and post the results to this thread. You can PM the ridge line length and max tree separation to me or post to this thread if you want.
There's a lot of detail in this post, but I think I know now what it is about.
My executive summary :
Of course the post is all about details in doing these things, but that's the thrust I think.Use your cord to measure the distance between trees. From this, the known length of ridgeline and marks on the cord, figure out how to center the hammock and how long the end-to-end suspension ought to be to give you a 30 degree angle on the suspension line. Use Marlin spike hitches on the single line, at the right places, to hang your hammock ends.
Making this useful for those who may not use a single line, or be able to precisely measure the distance between tree, I'll rephrase what I find to be key points.
First, estimate the distance between trees. You can step this off, you can stand between them with your hiking poles outstretched (about 12' tip-to-tip for me). You need to know how long your ridgeline is (or the distance between hammock ends), and subtract that off from the distance between trees. Divide that by two to get the distance from hammock end to tree, same at both ends. Call that distance D.
Now the length of suspension cord from hammock end to tree needs to be longer than D in order for the hammock to get the right hang (e.g., the suspension cord is at a 30 degree angle with respect to the ground). The precise length is D/cos(30 degrees). 1/cos(30 degrees) is very close to 7/6, a point made several times in HF by youngblood. Numerically D/cos(30 degrees) is approximately 15% larger than D. So if you can estimate a tip, you can estimate what D/cos(30 degrees) is. I'll offer an even simpler means of figuring out how long the suspension cord to tree should be using the marks on the cord .... make the marks 15% farther apart than they should be. So where there was before 12 inches to represent a foot, now use 14 inches (this is TeeDee's 2" per foot rule restated). To find the right length on the cord for a distance to tree of D, just measure D on the cord now in the exagerated scale. (aside...if you use marks on the cord also to measure the distance between trees, it would be best to have one color of marks for normal scale, and a different set of marks at a different color for the exagerated scale).
Finally, tie a slipped bowline loop at the right distance along the cord (what all my blather above is about), and hang it on the Marlin hitch toggle at the tree.
So if I have anything to add to improve the complete line suspension system, it is to eliminate the tables and the worst of the math by marking the line with two different scales.
The most useful thing for me out of the post was the idea of using a slipped bowline to attach the cord to tree. I'll be playing with that to see how I like it.
Last edited by GrizzlyAdams; 08-06-2008 at 16:50.
I never thought I would see grizz simplify a math thing to the point where I can understand it. Thanks tremendously. I got so bogged down in the original article, excellent tho it was, that I gave up in despair. Your recap is most helpful.
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Grizz - thanks for the summary. I tend to get wrapped up in the details and forget that others don't have my experience with what I am writing so that it isn't clear in their minds what I am describing.
Yes, you are right. I am using the cord to measure the distance between trees and then using that and the marks to set the sag. And you can estimate/measure the distance by any means. I have always found that I am way off by pacing and trying to guessimate it visually is worse for me.
I haven't tried the outstretched arms with poles - will have to try it.
My calculations are rounded off and add error and to add more error with my pacing or visual guesstimates just makes the procedure unworkable for me - far too much error. That's where I was before HC4U's idea of marking the rope. Marking the rope got my errors down to the point that I could reliably set the sag from tree separation. It would be great if laser range finders were cheap enough and light enough to use and carry.
I just remembered, I do have a Leica optical rangefinder - I'll have to try that. It's accurate from 1 meter to 20 meters and up to 7 meters the scale is almost as accurate as the markings on my hang rope. Just weighed it - 2.7 oz in its leather case. It would make a workable method. That would give me the distance right at the start, even before putting on the tree huggers. Knowing the distance fairly accurately right at the start makes things even easier.
front view of rangefinder
side view of rangefinder
I could mark a hang rope in metric and do the tables in metric ..... I going to have to try this - I think it will work.
I like the suggestion for putting the scale directly on the rope and using the 2 colors.
I would have one problem with it though - the scale as you suggest is based on a 30 degree sag angle. A lot of the time that is fine, but for large separations, 30 degrees can quickly get my butt on the ground or so high in the trees that I need a ladder - maybe lineman's spurs
I don't know - I've never done the AT or the PCT or any "maintained" trails, but the areas I do go are usually old growth and large separations are the norm. 16' may be considered "close" and findable a lot of the time, but 18' to 20' usually.
Where 30 degree sag works all the time, then a second color scale would be better. Great idea/modification.
I have been experimenting with marking webbing and rope suspension systems to aid in hanging hammocks. Like Grizz mentioned, I use a 31 degree sag angle because the cosine 31 is a convenient ratio of 6/7. I start the marks at a 12 foot span. From that 12 foot reference each foot is incremented 7 inches on each end, so that works out pretty well. What I mark is the span distance because I really don't care about the actual length of the suspension, I just want to know where to tie it off and the distance I do know is the span.
I am of the opinion that if there is one key parameter to get right in hanging a hammock, it is the height to tie off the hammock for the span you are using. If you get that right and are using a low stretch suspension system, about all you have left to worry about is centering the hammock between the span. Get that wrong and everything is more difficult. So my priority list is:
1- Span distance.
2- Tie off height.
3- Height hammock is above ground.
4- Centering hammock.
With a marked suspension system, centering of the hammock is hard to mess up. For a tie off height for most hammocks, I suggest shoulder height for a 12 foot span, head high for a 15 foot span, and as high as I can reach for an 18 foot span. (The tie off height is different for some of the larger Hennessy Hammocks. They should be tied higher by a half foot or more.)
I observe the height the hammock is above the ground and use that as the fine and final adjustment to make up for the inaccuracy I sometimes get in determining the span (by pacing or using my outstretched hiking poles. It just happens that I actually 'calibrated' my outstretched hiking poles the other day and found they are more like 13 feet instead of the 'old 12 foot rule' for me.) My fine adjustment is usually adding or subtracting some suspension but occasionally may be the tie off height, it just depends on how things look and feel.
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.
Using the 7" marking means that you have other means of measuring span distance accurately. How do you accomplish that?
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.
I would change your above ordering slightly and swap items 2 and 3. Hammock height is what I want and tie off height follows from hammock height and span distance. With a ridge line, computing the tie off height from hammock height and span distance is a simple trig problem. Without a ridge line, you have a much more flexible problem and have to fall back on the "art" of where to place the tie off on the trees as you do with your "rules of thumb" below.
Of course, if you know what the distance between your hammock whipping is when hung, then you know the "virtual" ridge line length and can use that as Grizz mentioned. You then have the problem of accurately measuring span distance. The hang rope with built-in ridge line solves that problem as does my Leica optical rangefinder.
I really think that I would change your list even more in that items 3 and 4 are not items that are unknown, but are my final goals in hanging the hammock. I have the following list in my head when hanging the hammock:
- accurate span distance measurement
- sag angle and,
- tie off point height
I can measure 1, and then mentally adjust 2 and 3 to get my desired/known hammock height. Centering the hammock then follows from sag angle and knowing the measured amount of slack to allow and using the marks on the suspension to accomplish that.
That's the reason I might be carrying that Leica optical rangefinder in the future and will certainly be doing testing with it in the days to follow.
Knowing the span distance accurately immediately with the rangefinder without even having to put the tree huggers on the trees, means that I immediately know several things:
- if a 30 degree sag angle will be workable
- what sag angle I can use
- how high to place the tie off, i.e., how high to place the tree huggers
All of that falls out immediately from the span distance since I already know how high my hammock will be and the fact that I want it to be centered.
Also, you may not "care" about the suspension length, but what you are doing assumes that, at least theoretically, you know what it is. Otherwise your procedure for the 7" markings makes no sense to me. It is based on suspension length.
Here is the geometry I am basing this on. A structural ridgeline can alter this, or not, depending on what the sag of the structural ridgeline is. Hopefully the 7" of suspension per 6" of span is evident from the diagram. It all works out, but as TeeDee pointed out, the accuracy of determining the span is the rub. I'm not sure too many people will want to use something to precisely measure the span, I think most people will have to work around that inaccuracy.
And the virtual ridgeline trick, I have used my version of that for years. I make all my backpacking hammocks such that the attachment points for the hammock bugnet will be at a 9 foot horizontal distance when the hammock sag is 31 degrees. I mentally subtract that from the span and multiply the results by 0.6 to estimate the amount of suspension needed on each side from that point. I use various points from my finger tips to elbows, armpit, nose, etc to estimate those lengths. It gives me a ball bark hang which I make fine adjustments to. I know 0.6 isn't the exact number but my measurements aren't precise enough to warrant worrying with multiplying a two digit number.
Last edited by Youngblood; 08-06-2008 at 22:18. Reason: wrote "horizontal difference"... should have been "horizontal distance"