Discuss - Hammock Hanging Method Addendum

[warbonnetguy]

my old hh has a very thin nylon ridgeline, which of course stretches under tension rather than fixing the sag angle of the fabric like they always claimed it did. i don't know when they switched to a static line, but there was a thread awhile back about them breaking and it seemed quite a few had had it happen. it may be something that started happening when they switched away from the nylon ridgeline which may have been more recently, who knows, but IMO they shouldn't be breaking even during a tight hang. afterall, if you need to hang from a long span, you might actually need a fairly tight hang for height reasons.

it seems like there would always be less force on the ridgeline than on the suspension, so thinner line could be used, but it shouldn't be so thin that it breaks. i suppose i see what you mean about the ridgeline being a good place for a weak link, but i would rather have the entire suspension be strong enough to handle a tight hang with the max load inside, and not worry about my suspension lines breaking. actually, i really don't care where the weak link is, just so long as i'm not heavy enough to break it

going from the figures on the hitchcraft thread, a 250# person and a 15 deg sag angle would only result in 483# on the suspension. factor in some bouncing and maybe 500# or so. your tree straps and/or suspension line/webbing should be able to handle that much force pretty easily, so i bet the ridgelines that did snap, were at forces way below what the actual suspension could handle, suggesting that it was not just a weak link, but a severely weak link considering that both tech cord and poly webbing should be able to handle at least 1000# of force.

i've found out that some of the slipped knots i've been using are actually weakest link in my suspension. a couple of them that had never slipped before, did when i had 2 people in the hammock.

[Ramblinrev]

one of the reasons I switched to ring buckles was to make it easier for me to deal with a longer span. I have Safari which is a big one. There is a lot of fabric in that hammock that can hang pretty low. I was beginning to have problems hanging the huggers high enuf and still be able to lash the line. I will almost always introduce a bit of sag to the ridgeline and rarely tighen it up a tight as I can. This cuts down on stress on the ridgeline but also reduces the initial drop that occurs when I get in. On other forums particularly I have seen talk of people cranking those hammocks as tight as they can to eliminate the initial drop. Actually from what I have read here and from my own experience it seems to be the other way around.

[Youngblood]

Brandon,

I was under the impression the HH ridgeline was always a low stretch (polyester?) cord. I had some of the earliest ones, have seen some in the last couple of years, and I believe they were all low stretch cords. As you mentioned, light weight nylon cord won't set the sag angle as it will stretch too easily under tension. If you have nylon cord, I suspect there was a manufacturing snafu somewhere. Don't doubt what you say, but I don't think that is not the way they are suppose to be.

If you are curious about the forces on the suspension system, I have some files posted in the files section of the Yahoo hammockcamping group that have diagrams and spreadsheets for handling the forces on the suspension lines and a structural ridgeline. You can use the spreadsheet to plug in whatever numbers you like and the diagram is intended to show the physics of what is going on. The suspension lines always have more force on them than the structural ridgeline does.

[warbonnetguy]

yeah, i once took it out and tied it to a beam and it had ALOT of stretch in it. pretty sure i did the burn test on it too. i was fairly sure it was nylon (mainly b/c of the amount of stretch), but i can't say cause i tossed it. it was one of the first asym versions i believe.

i may check out those spreadsheets, but i was mainly interested in what the lowest sag angle one could achieve was and how much force that would put on the suspension as a percentage of actual bodyweight. i think i've got a handle on that thanks to the hitchcraft thread.

[Youngblood]

After I wrote that post I recalled that someone else once posted some information about their bugnet getting stretched out. When they posted that, the only way I could figure that happen was if their ridgeline also stretched. Maybe some got sent out with the wrong cord for the ridgeline.

[Schneiderlein]

Just before leaving for Germany, I read both articles by TeeDee, and in my half-sleep on the plane ride, I had an idea. Well, that's usually an easy way for me to get myself in trouble, so I thought I'd throw it out here since I unexpectedly got internet access.

I really like the idea of saving weight and doing away with much of the bulky webbing, but I have come to like the convenience of the cinch buckles. The thing that I find really appealing about TeeDee's solution is the simplicity of the knots. I am not a knot person, but I think I can learn a marlin spike hitch and a bowline knot and remember it without having to practice every day. Then, there is the inconvenience of the measurements and tables, so I thought maybe I can streamline that a bit. The basic premise here is that you always go for the same sag angle and put up your tarp before the hammock anyway, and that you are able to center the tarp fairly well between the trees. With the tarp already in place and centered, I think it would be fairly easy to figure out where to tie the bowline loops on the hammock suspension using the two-color scale suggested by Grizz.

Unfortunately, there is a bit of math involved here (which I have not really gone through in detail), but from quickly catching up on other posts, I got the impression that the mathletes are ready to come out of hiding again. So, here it goes. Knowing the difference between the length of the tarp ridgeline T and the rideline H of the hammock, I can mark a start point on the hammock suspension for a target sag angle. That would be S = (T-H)/(2 * cos(angle)). This length S will always be under the tarp no matter what the tree separation, as long as the hammock sag angle is constant and the tarp ridge line is horizontal (and neglecting other higher order effects such as stretch in the tarp). So, I would mark the hammock suspension cord at a distance S from the hammock body with an initial mark, and then have black marks at 3" intervals, and red marks at 3"/cos(angle) intervals. To set up, I would line up the first mark on the hammock suspension with the edge of the tarp, and measure the black ticks between the tarp edge and the tree. If not sure how well the tarp is centered, I could repeat this measurement at the other side of the tarp and take the average. Now, all I would have to do is find the same measurement on the red mark scale and tie the bowline loops, and I should get pretty close to the correct sag angle, and have the hammock perfectly centered between the trees. The only adjustment then would be the height at the tree.

This sounds almost as convenient as cinch buckles. I am wondering how consistent such a procedure would be in terms of the sag angle, or in other words, how much of a height adjustment might be necessary once the bowline loops are tied. I guess I'll have to do some math to figure it out, and analyze the variation in sag angle as a function of where the bowline is placed and how far apart the trees are.

I have a feeling that this might be practical and easy enough to where I would give up the convenience of the cinch buckles for the savings in weight and bulk. I have not read every post in detail, but it seems that the distance of the marlin spike hitch from the tree is pretty consistently between 5-6", and that could be incorporated into the first mark on the suspension, and the tarp sag angle could be accounted for in first order approximation by reducing the scale of the red marks by a small amount. What I am trying to say is that with some heuristics, it should be possible to get pretty close to the desired sag angle.

Forgive me if any of this might sound incoherent or not make any sense at all, I am a bit jet-lagged. I would appreciate any feedback on this, and maybe a hint on what works to permanently mark coated rope (I think the coating on my rope is called Samthane or something like that).

[TeeDee]

Unfortunately, there is a bit of math involved here (which I have not really gone through in detail), but from quickly catching up on other posts, I got the impression that the mathletes are ready to come out of hiding again. So, here it goes. Knowing the difference between the length of the tarp ridgeline T and the rideline H of the hammock, I can mark a start point on the hammock suspension for a target sag angle. That would be S = (T-H)/(2 * cos(angle)). This length S will always be under the tarp no matter what the tree separation, as long as the hammock sag angle is constant and the tarp ridge line is horizontal (and neglecting other higher order effects such as stretch in the tarp). So, I would mark the hammock suspension cord at a distance S from the hammock body with an initial mark, and then have black marks at 3" intervals, and red marks at 3"/cos(angle) intervals. To set up, I would line up the first mark on the hammock suspension with the edge of the tarp, and measure the black ticks between the tarp edge and the tree. If not sure how well the tarp is centered, I could repeat this measurement at the other side of the tarp and take the average. Now, all I would have to do is find the same measurement on the red mark scale and tie the bowline loops, and I should get pretty close to the correct sag angle, and have the hammock perfectly centered between the trees. The only adjustment then would be the height at the tree.

Beautiful - I knew that others could improve on the method.

I like what you have done very much. It makes the marking of the rope slightly harder ( or more depending on your math skills - but the math could be farmed out to those of us on the forums that really like it ), but simplifies the set-up by making the tables I use un-necessary.

I will probably incorporate your idea into my setup, but I will not be leaving the tables behind. The two color marks dictate a single sag angle. I find that when I get to long tree separations I like to use a smaller sag angle so that I don't have to climb the tree to hang. Thus, I can always fall back on the tables when necessary. But the two color marking is great for the great majority of hangs and simplifies things.

As far as noting the distance from tarp to tree on both ends of the tarp to essentially get the tree sep, I have modified my personal use of the procedure. I use a separate ridge line for the tarp. I run the tarp ridge line from tree to tree and then hang the tarp from the ridge line with Prusics. The Prusics always stay on the ridge line. I use guy line tree huggers for the tarp ridge line to contain any contamination from the tree away from the ridge line proper and hence the tarp. The guy line tree huggers weigh about 0.2 oz each, so easy to justify there.

So I got to thinking (dangerous) that I could use the tarp ridge line to measure the tree sep and then tie the bowlines on the hammock ridge suspension as I'm putting the tree huggers for the hammock up. That eliminates the back and forth step of the procedure. To accomplish this I marked my tarp ridge line guy line starting at 12' and marks every 3". I use a 30' length of guy line for my tarp ridge line and 12' lengths of guy line for tree huggers for my tarp. I have a bowline on one end of the tarp tree huggers and I pick up a stick from the ground for the Marlin Spike Hitch toggle. One end of my tarp ridge line has a bowline, slip that over the Marlin Spike hitch. Walk to the second tree playing out the guy line, set tree hugger, wrap tarp ridge line around Marlin Spike Hitch and pull taut and I can read the tree sep right from the tarp ridge line immediately (adjusting for distance from Marlin Spike HItches to trees again).

This sounds almost as convenient as cinch buckles. I am wondering how consistent such a procedure would be in terms of the sag angle, or in other words, how much of a height adjustment might be necessary once the bowline loops are tied. I guess I'll have to do some math to figure it out, and analyze the variation in sag angle as a function of where the bowline is placed and how far apart the trees are.

I find the method more convenient than any of the buckles. The buckles made adjusting easy, but didn't eliminate it. By using my tarp ridge line to do the measuring, I no longer have any adjusting to do at all. By knowing the tree sep before I even put a hammock tree hugger on a tree, I know exactly how high the tree huggers have to be and how long the hang rope has to be to get the sag I want.

Also, I have found the sag angle to very consistent within the small error expected from the accuracy with which the tree sep is measured.

[GrizzlyAdams]

Just before leaving for Germany, I read both articles by TeeDee, and in my half-sleep on the plane ride, I had an idea...

I read your post a couple of times. Something implied that isn't explicit but is a good idea is that the black marks (horizontal scale) are on the tarp lines...you're using these to measure the distance between the trees. Red marks are on the hammock suspension line.

Then, yes, what you describe is spot on
After you pitch your tarp and know what the distance between trees is, you can figure the height to put the webbing straps, to give you the hammock height you want. I'd gin up a table or something to put in the hammock bag. To measure the height put some knots at 3" separation on an 8' piece of mason line. (Assumes the ground is flat though!). Attach the webbing, measure out the right number of red marks on the suspension line, and tie your slippery bowline.

That said, I've had quite a lot of trouble with slippery knots being difficult to undo when I use single braid dyaneema. What I've moved towards, tentatively, is to have a fixed bowline at one end of the suspension cord. That gets looped on the toggle at the tree. If marked by the "red" marks then the counting is done the same way, but towards the hammock rather than towards the tree. That length will get you to where the suspension line goes under the tarp. The additional length needed to get you to the hammock is fixed after that, so add what is needed to get you to close to the hammock end. What you do after that is your business. If the hammock has a ring at the end you can tie a round turn with two half hitches. Or put in a Marlinspike hitch with a stout toggle on the suspension cord and attach to a loop that comes off the hammock end.

As for marking cord, I haven't marked my suspension cord. I don't think a marker would leave anything permanent there. Colored thread interleaved among the strands of the dyneema would do it, but that's a lot of work!

Grizz

[Ramblinrev]

Colored thread interleaved among the strands of the dyneema would do it, but that's a lot of work!

Grizz

If you did a whip length along the rope... say 1" or so long the thread should be tight enugh it would slide around and it is not as much work as interleaving threads in the rope itself. of that matter seal a wrapping of thread with the heat shrink tubing.

[GrizzlyAdams]

If you did a whip length along the rope... say 1" or so long the thread should be tight enugh it would slide around and it is not as much work as interleaving threads in the rope itself. of that matter seal a wrapping of thread with the heat shrink tubing.

That's a good idea. I was whipping the ends of that stuff after cutting it just the other day. So pop a bit of this every so often on the cord.

Could do this sitting and watching a movie at home some night...

Grizz