Asymmetric Nova Harmony Hammock

[JackM]

Where to begin? While reading a thread here, which I have now lost track of, I encountered a discussion of Tom Hennessy's original patent application in which he stated in effect that the flatness of the lie could be improved with an asymmetric cut of the end of the fabric. That started my engineering brain to work. My first effort was a simple "proof of concept" using cheap ripstop nylon, and what turned out to be a flawed approximation of the curve. This first attempt proved the concept, but I found the lie to be a bit beyond flat. Here is a drawing of the first version:



It took a couple of iterations, but I ultimately came up with a calculation of the curve that provides a perfectly flat (theoretically) lie. This does not allow for stretch in nylon fabrics, more on this later. In the meantime, I read about jellyfish's NOVA Harmony Hammock and decided to incorporate her proportions into the next iteration. The following illustrates the derivation for the calculation of the end cut curve:



I developed a spreadsheet for calculating the curve which is available here: https://docs.google.com/spreadsheets...gid=1208042099

And here is a drawing of the Asymmetric NOVA Harmony Hammock that resulted:



The resulting hammock is pictured here, modeled by my friend Kiwale, a graduate student from Tanzania (East Africa):



There are more pictures in my Album of the same name, and I will be discussing some of those in future posts.

[Cabmanhang]

That looks like a very well thought out and designed hammock. Would love to see more pics of it in action and hear more about the comfort. Let us know how it goes.

[JackM]

FULL DISCLOSURE

The material for the hammock is Hexon 1.6, 4 yds. of Forest Green for the main body (Note that the design calls for 145", when I measured the fabric I received from Dutch that was exactly what I had. Thanks Dutch for the lagniappe.), and 2 yds. of Burnt Orange for the end caps and and 2" continuous bias tape for the side trim. I needed almost one square yard for continuous bias tape, and if I had made the end caps single layer the remainder of one yard would have been enough. Since I made the end caps double layer I needed a little more than a linear yard, hence two yds. I have one square yard left over, plus a scrap, for a stuff sack, etc.
The lie is very flat and very comfortable across the diagonal, but getting in can be a little tricky. The first time I lay in it I backed up to what I thought was the middle, sat down and leaned over on the diagonal, and promptly fell on my head on the opposite side. I have since learned to sit down a little shy of center and initially lie down approximately on center. Then it is quite easy to adjust position until lying on the diagonal, and quite stable as well.
In addition to the tie out per Jellyfish's dimensions, which consists of a Beastie on the outside and a "convenience" D ring on the inside, I also added D rings, inside and outside, 10" either side of the main tie out, similar to Dutch's Chameleon. In fact, in the pictures I am using the Chameleon harness on these D rings.
I have Knotty Mods on both sides buried in the bias tape. The fixed end is buried and the adjustable end comes out through a seam in the bias tape. The total length is 27". Unfortunately, I had them installed before I remembered Knotty's instruction to position them around the "foot box", NOT in the middle, but so far it doesn't seem to matter much. Maybe I will do it right next time?
The end caps are double layer, to Jellyfish's dimensions, but with 1/16" shock cord fixed across between sides to insure that the end cap is held tightly against the future bug net, similar to the Chameleon.
Dutch's 115" double pull separating zippers are installed both sides. They end 6" back under the end caps.

Coming next: Folding the ends and attaching the end lashing.

[JackM]

Folding and Lashing

The basic method for folding is taken from the following video: https://www.youtube.com/watch?v=ceuXNuQqcYw

I found that these light,slippery fabrics are very difficult to manage with my old, uncoordinated hands when making multiple folds and trying to keep them lined up. After some thought I came up with the following:



I bought a steel flat bar 1 1/4" X 1/4" X 36" from Home Depot and cut it in to six 6" pieces. As an aside, these also make convenient weights for holding fabric in place on the cutting board. For this purpose I used three of these bars for folding fabric. In the picture the short side of the fabric has already been folded starting at the gather point and working outward. It is being held in place by the bar on the right. On the left I am folding the other side, also to the gather point which is in the middle. I place one bar on the fabric with a little sticking out, then fold the fabric over that bar and place the third bar on top and fold the fabric back over again. Then I carefully slide the bottom bar out letting the top bar fall down on to the accumulating folds, and repeat. With a little practice I could fold the material very neatly into 1 1/2" folds (1 1/4" for the width of the bar and 1/4" for its thickness. From there the only difference from the video is that I made a round hole and used an 8" loop of Amsteel in lieu of flat ribbon.




I couldn't decide whether to make the end socks green or orange so I made one of each.

The ridge line is 1.75 mm LashIt in an adjustable woopie sling configuration:

[jellyfish]

Wow! So much geometry!!! I love it. Beautiful hammock.

[JackM]

That looks like a very well thought out and designed hammock. Would love to see more pics of it in action and hear more about the comfort. Let us know how it goes.

Thanks Cabman, if it ever stops raining here again I will get some more shots, and do some more testing.

[JackM]

Wow! So much geometry!!! I love it. Beautiful hammock.

Thanks Jellyfish! I have been awaiting your return with baited breath. I guess you never thought it would get done since it has been almost four weeks since I first contacted you about my ideas. Since I am a complete newb at both sewing and hammocks it has taken a while. I wish I had done a few things differently (like the knotty mods), but it has been a fulfilling experience overall, and I can't wait for the next adventure. As I mentioned before, I have plans for a purple and gold Geaux Tigers (LSU) hammock for my granddaughter, an alumni. That is on hold since I tried to order the fabric from RBTR and found it "out of stock". The configuration of that one will also depend on further testing of the Asymmetric. I am sure a conventional gathered end would be less work!

Thank you so much for your earlier encouragement.

[JackM]

Update time - and probably last post

First, from the drawing to the picture of the finished product, you may have noticed that the angle of the asymmetric lie had reversed. This is because I got confused when doing the folding an inadvertently flipped the hammock over. I didn't realize the error until I hung it. Too late to change now.

It has rained so much the last couple of months that my yard is a swamp, and I have been forced to move to a stand on the carport. For the stand see this thread: https://www.hammockforums.net/forum/...od-style-stand

For comparison purposes here is a picture of the Chameleon without tie outs:


You will note that the edges of the hammock are on top, actually all the fabric is at the same level except for where it comes out of the gather. If you sit on it in this configuration the weight is evenly distributed across the entire hammock. Now have a look at the asymmetric in the same configuration:


Note that the edges are on the bottom, and in fact, only the center line of the hammock is on top. If you sit on it in this configuration all the stress is on a very narrow strip down the middle. NOT GOOD! It hasn't failed after several sits, but not good anyway. The next picture is of the hammock unloaded, but tied out in a manner similar to what Dutch recommends for the Chameleon, not straight out but more toward the ends. This hammock really needs to be tied out firmly.


Note that the lie is very flat, and, in fact, very comfortable. The next picture is with the lie weighted with a 4X6 slightly less than 6' in length, I don't have a model readily available.


So far as I can determine the weight is very evenly distributed across the lie. The final picture is the one I really like. It is not so much attributable to the asymmetric cut as to the fold pattern. Note the even way in which the fan folds play out across the length from the gathered end to the weight.


In this picture the Knotty mods take the slack out of the edges without interfering with movement.

Summary conclusions: The asymmetric cut hammock is very comfortable when lying on the designated diagonal and for sleeping, but only on the proper diagonal. On the other diagonal the sway back is pronounced and the shoulder roll unacceptable. The main problem I see is when using the hammock as a chair. When sitting short of center the weight is concentrated on a small area of fabric and there is a noticeable tendency to slide forward toward the edge. Sitting on the center line is very comfortable, but all the stress is concentrated on the center line. Sit beyond the center line at your own risk , you will very likely slide down the back side and land on your head.

As I have said, my next hammock project is a purple and gold "LSU Tigers" hammock for my grand daughter. I was hoping to make it a double layer of 1.0 HyperD, but RBTR is still out of 1.0 in those colors so I just ordered 1.6 HyperD for a single layer. I very much like jellyfish's design of the NOVA Harmony hammock and will go with that basic design, but will probably stick with the fan folded, heat fused ends.

[pdxhanger]

I tried to make an asymmetric GE hammock similar to yours for the longest time. I had 4 goals:

1. "Calf ridge" under my knees instead of my calves.
2. Feet & legs lower than my torso
3. No uncomfortable pressure on my heels
4. Hammock length of 10 feet or less

I eventually gave up and started working on a bridge hammock. In retrospect, putting a ridge where I wanted it instead of just trying to get rid of it is probably a fool's errand in a GE hammock, because the ridge will never go straight under the legs regardless. I also tried to achieve my objective by only modifying one end, because modifying both ends just seemed too complicated.

Anyway, I'm wondering about your design. Do you have any "calf ridge" (or ridge in any other spot)? Are your legs above, below, or flat with your torso?

I've been looking at the Simply Light Streamliner and seeing that he is curving his ends, but in the other direction (middle longer than sides). Derek at the Ultimate Hang says that this effectively eliminates the calf ridge, making a 10 foot hammock feel like an 11 foot. I'm thinking about trying a GE similarly curved at the ends, but with the foot side longer than the other side so that my legs are a little lower than my torso. When I looked at yours, though, I started to wonder, because the way you are curving (middle shorter) was what I was trying to do, and it still makes intuitive sense for a flatter lay (lie?)

[Brad32825]

Great looking hammock!