Unnecessarily Complicated Hammock 3.0

[SteelToe]

Here's the 'plan' I'll be following for this first attempt; everything I see says about 3" deviation at the ends & 5" on the sides is the max worth looking at, and the sides require the most adjustment of any part of the hammock. I won't do the side cuts at first, since I want them to follow the true as-used tension lines while I'm inside it, but I expect them to be assymetrical catenary/hyperbola shapes like I've drawn.

One last question; in looking over whipping vs. channels, has anyone tried pleating the fabric before sewing into channels? Seems like a way to get some of the results from whipping (such as "W" style whipping that spreads the calf ridge into two parallel ridges) but in a much more controlled, easy to see/measure manner. Once gathered, I can't see how pleating stitches only 6" or so from the end would be significantly stressed by a person lying in the thing.

Oh, the 59" width will increase to whatever the wide Dutch Hexon stuff comes in at. From what my way-too-thorough research has shown, width is the biggest factor for a comfy, flat diagonal lay. Length is what helps even out lines of high stress like the calf ridge. That fancy Ninox thing has a notably wide floorplan, and I can't help but wonder if that's the real 'X factor' more so than the end channels. With so much width, I expect there to be a ton of unstressed floppy fabric in places, which I'd be able to hack away to open things up & reduce bulk.

[hutzelbein]

Hennessy hammock bodies are not rectangular, but are actually parallelogram shaped before being gathered.

I don't know how off square they are for sure, but they're not just rectangles

I'm interested: where did you get that information? I don't want to undo my HH just to find out, but I can see or feel nothing that suggests that the hammock body is not rectangular. Did you see the (very old) thread on how to make a Hennessy clone? wilsonbmw undid his HH and took pictures. Or did HH change its construction?

[leiavoia]

From what my way-too-thorough research has shown, width is the biggest factor for a comfy, flat diagonal lay.

My personal experiments have all shown otherwise. Even with monsterous sizes, it’s still an orange slice shape. It doesn’t get flatter by making it wider. Quite the opposite.

I would recommend getting a section of fabric and whipping a few iterations of what you are imagining. Whipping let’s you rapid prototype designs.

[hutzelbein]

Actually, several factors influence how flat you can lie. Width only helps if there is sufficient length. With a short but wide hammock, the sides come up like a bathtub. But they come down, the longer the hammock becomes. Obviously, width beyond your body size doesn't increase flatness.

Provided the hammock is long and wide enough, the factors that have contributed towards a flat lay most were lack of fabric stretch and lack of sag. It's possible to shape the ends, but you are very limited with regards to depth of the curves if you don't want to use a sleeping pad for stabilizing purposes (like 90° hammocks need). Anything deeper than 1" (on each end - so 2" in total) resulted in an uncomfortable lay. I built about 20 prototypes, but found the traditional rectangular shape worked better.

[leiavoia]

Actually, several factors influence how flat you can lie. Width only helps if there is sufficient length. With a short but wide hammock, the sides come up like a bathtub. But they come down, the longer the hammock becomes. Obviously, width beyond your body size doesn't increase flatness.

Provided the hammock is long and wide enough, the factors that have contributed towards a flat lay most were lack of fabric stretch and lack of sag. It's possible to shape the ends, but you are very limited with regards to depth of the curves if you don't want to use a sleeping pad for stabilizing purposes (like 90° hammocks need). Anything deeper than 1" (on each end - so 2" in total) resulted in an uncomfortable lay. I built about 20 prototypes, but found the traditional rectangular shape worked better.

Agree with all of that.

I've been working with krinkle taffeta tableclothfactory sheets lately. They are very stretchy and get a very bad sidewall if i don't add a dramatic convex whipping on the end.

With stiffer fabrics like off-the-shelf ripstop, a straight-across gather works best.

[SteelToe]

Because a hammock becomes increasingly --spherical, I guess would be the word?-- as it gets wider, my thought is that the end-channel/whipping shaping effects would become more impactful. The width is simply to give me room for a more diagonal lay, the end-shaping would flatten the floor profile out when weighted, and the side-cuts would simply remove unneeded material. That fancy Ninox thing appears to be pretty darn wide (84" IIRC) and incorporates what they claim is a substantial end-channel curvature, to obtain "the flattest lay evar" or some such.

[leiavoia]

Because a hammock becomes increasingly --spherical, I guess would be the word?-- as it gets wider, my thought is that the end-channel/whipping shaping effects would become more impactful. The width is simply to give me room for a more diagonal lay, the end-shaping would flatten the floor profile out when weighted, and the side-cuts would simply remove unneeded material. That fancy Ninox thing appears to be pretty darn wide (84" IIRC) and incorporates what they claim is a substantial end-channel curvature, to obtain "the flattest lay evar" or some such.

That’s correct... if you are a solid steel pipe. The problem is that you are a soft squishy human. If you let the sidewalls out by curving the ends, what actually happens is that it all collapses and you slump unto an awkward upside down arch-backed mass.

You can avoid that by staking the sides out really well, but then your hammock body is completely dependent on guylines.

[SteelToe]

Actually, several factors influence how flat you can lie. Width only helps if there is sufficient length. With a short but wide hammock, the sides come up like a bathtub. But they come down, the longer the hammock becomes. Obviously, width beyond your body size doesn't increase flatness.

Provided the hammock is long and wide enough, the factors that have contributed towards a flat lay most were lack of fabric stretch and lack of sag. It's possible to shape the ends, but you are very limited with regards to depth of the curves if you don't want to use a sleeping pad for stabilizing purposes (like 90° hammocks need). Anything deeper than 1" (on each end - so 2" in total) resulted in an uncomfortable lay. I built about 20 prototypes, but found the traditional rectangular shape worked better.

Totally agree on the multiple intertwined factors; I did my previous experiments with a bridge architecture to try & simplify that aspect of things as much as possible, and it's still very complicated how everything interacts. Kind of like accurately modelling a bicycle's stability mechanics, a hammock is a deceptively complicated engineering problem.

This fabric is 1.6 Hexon, so it should be fairly rigid at the end of the day (I think) so fabric stretch is hopefully eliminated from the list of variables. Also, it may not be apparent in my 'sketch' but the end-channel shaping is predominantly at the outer edges; the middle third or so of the fabric will be a simple rectangular profile, but the side walls will be slackened where they start to slope upward on your sides, then reversed right before the edges (outside your body's footprint) to pull things taut enough the fabric doesn't ball up into a rope beneath you, and finally reversed yet again at the very edge so it doesn't carry a concentrated load.

One idea I had was to whip the hammock ends while a weight was placed in the fabric; basically, a 'dummy' (laundry bag) would be laid along the desired diagonal, and the end of the fabric lifted up, gathered, and whipped so as to keep as constant a tension across the width as possible, then repeating the same on the opposite direction. In theory I would think that arrangement would tend to remain flat as the two whipped ends where raised, assuming they were gathered/whipped under tension similar to lifting the object. In practice my greater weight & uneven shape/weight distribution would surely mess with things, but it seems plausible as a starting point. I'll probably mark the fabric once I find a gather profile that feels decent, whatever it is, and lay things back out to see whether it's a wave, double-u, catenary arc, or simple straight line.

One last question I had; I have read that whipped-ends can be effected by the size & number of accordion folds needed to gather them. If this is the case, what advantage does the end-channel type construction have over whipping, since it would seem to lack that degree of freedom? (I'm aware this is probably a can o' worms type question here) Both channels & whipping appear to do the same thing, structurally (big wad of fabric for a loop of rope to wrap around)

[leiavoia]

One idea I had was to whip the hammock ends while a weight was placed in the fabric.

I do this with pillows. Hang hammock on one end. Softly tie the whipping, lift other end up off the ground and gently pull out the lines you want.

One last question I had; I have read that whipped-ends can be effected by the size & number of accordion folds needed to gather them.

False. It all gathers to the same end. Try it if you don’t believe.

If this is the case, what advantage does the end-channel type construction have over whipping, since it would seem to lack that degree of freedom? (I'm aware this is probably a can o' worms type question here) Both channels & whipping appear to do the same thing, structurally (big wad of fabric for a loop of rope to wrap around)

End channels are easier to make. Whipping is for people that want to customize or don’t have a sewing machine.

[SteelToe]

You mean you aren't light as a feather, and stiff as a board, lol?

Guylines aren't the worst thing in the world --my tarp still needs them, after all-- plus it might make going back to a mattress an easier transition. Like I said, that appears to be the approach the Ninox is taking (a whopping 4 tie outs). I really wish that product had more reviews (and less marketing), since it does look like they have tried a legitimately methodical/engineered approach...but so have others here, to very mixed results. The ones that are out there appear to be positive, though.

As far as the floor bunching up beneath the user along the center line leaving them Pringle-shaped; if the fabric out past the shoulder and knee, where it starts to slope up the sides rapidly, is cut so it becomes gradually more tensioned, I think that would pull the floor back out from the center, along a mostly horizontal vector because of the steep curvature (so your knee/shoulder would be pulled more inward than upward). There would be squeeze as a result, but across your whole body, not just the shoulder blades. I honestly don't know if that'd be better or worse, until I try it.

Just as an attempt to nail down the starting point for a variable; what is a good 'typical' structural ridgeline length for an 11 to 11.5 foot hammock? My hammock stand is unfortunately rather flexible (think sling-shot) so in the past I tied a ridgeline between the ends to pre-tension it for hammock testing.