Hammock with curved ends?

[hutzelbein]

I have experimented with different curves on the ends. Curves change the lay, but I don't think they do much to fight the calf ridge, other than changing your direction.

The calf ridge is created by the weight of your torso. Due to its weight, it's pushed deeper into the fabric. Your legs are lighter, that's why the fabric is not stretched as much. The only way to prevent the effect completely is to use a fabric that doesn't give much under your torso. Polyester has very little stretch; my 1.4oz PolyD and 1.6oz ripstop polyester hammocks did not have noticeable calf ridges. But they also don't feel as nice to me as nylon. With the 1.6oz ripstop polyester I felt like lying on a concrete floor.

In my opinion the best way to deal with a calf ridge is to move into a position in which it doesn't bother you. You can achieve this by either going more perpendicular or inline. If you go more perpendicular, the ridge is under your upper legs, which are heavier and less sensitive to the pressure. If you go more inline, your legs touch are greater area of the ridge and the pressure is distributed better. Of course there are other tricks as well, like pulling the fabric tighter or using a pillow.

Curved ends on the hammock like this ) ( will relax the sides somewhat and enable you to lie more perpendicular - so you might solve the calf ridge problem this way.

One piece of advice, though: don't make the curves deeper than ~0.6", otherwise you'll create a new ridge, running along the center of the hammock. Not very comfortable.

[HarryRSole]

I recommend that you NOT do that. A straight-across end gather already does an excellent job of keep occupants inside.

If you tighten the edges, it creates a skinny band of high pressure when you sit on it to get in. This can make the fabric tear. That's bad. See requisite Shug video: https://youtu.be/xrfBrIEH2-U?t=301

Thanks, I did look at the method used on Just Jeff's camping page and I completely agree with you. I too had a bit of sadness when ole green bean broke.

[WillUpnDown]

This is a really interesting problem. hutzelbein sums up the basic problem weight distribution and shape of the human body and pressure points (the calves problem). Then there is the fabric tension problem. Too much on one point and fabric is more likely to fail at that point. This discussion started with the idea of a curved spreader.
I'm working on a parallelogram idea. [The basic camping hammock trick is a 'flat enough' diagonal lay. The natural flat lay is of course perpendicular to the axis. If you can rotate this even a little bit that brings the 'flat-enough' diagonal off this perpendicular: the parallelogram does this. But it probably won't solve the calf problem.
Shug's tragedy (rip) was caused by too flat a stretch. The edge is where it happened. (This is a standard physics problem. With a 30 degree hang, the tension force on each sling is equal to the force of the hanging mass. Basically if you weigh 70 kg, then there's 70 kg on each sling (140 total). If you could tighten your suspension to get a near zero degree hang--straight across, than the force of any hanging mass would approach infinity.) Consider if Shug's suicide-straight hang was desirable? We'd just reinforce the sides with Dyneema cord until it worked.
The natural goal of this curved spreader idea would be to make a hammock that conforms comfortably to the body, but still lightweight and easy to make. I can see the day when we're sewing wonky meandering seams at the ends of our hammocks, then inserting short carbon-fiber spreaders, threading through a couple of nettles lines (my last name btw, so take any advocacy of nettles from Nettles with skepticism).
(Could a curved seam and a straight short spreader accomplish the same thing as a curved end?)
In the end an ideal camping hammock will probably have either a left or right lay, and be made from patterns that do what hutzelbein is talking about. There'll be a few ripped hammocks along the way, and if we have to add dyneema to the edge seams than okay. Let's get started reinventing the hammock.

[OlTrailDog]

90 degree hammock = calf ridge problems solved. Flat lay and side sleeping an added bonus.

[WillUpnDown]

To experiment with parallelogram form. I'm making a pair of simple 'clamp' spreaders.
Each spreader will be about 15 inches long with 12 1" marks in the middle. Then the uncut fabric will be marked for the 'hang' to be tested.
My angle gives me an end 78" long. Divided into 12 parts I get about 6.5" between marks.
This means I have to gather about 6.5" of fabric for each 1" space on the spreader. I'll then clamp the spreaders together with 1/4-20 bolts. A couple of lines will attach to suspension.

Where this may be interesting here is the bolts can be loosened up and parts of the 'gather' can be moved farther in or out of the spreader-clamp to change the tension on parts of the hang.
A drawing is attached. Note: I don't know how closely to a gathered or whipped end this can match or if it can test the curved gather that's being discussed here. These spreaders are not intended to be a part of a finished hammock; they're just for testing. Also, no idea what it'll do to the rip-stop. (I might add some neoprene strips for padding.)
Hanmock Lab Spreader.pdf

[Blargendarg]

Apologies for the resurrection, just looking to find discussion from the past on this subject. I've spent an extensive amount of time on this concept and have found this far that it's the only way to get a truly flat *and* level lay w a gathered end hammock, that the curves that succeed are dramatic, asymmetrical and difficult to find due to the variety of factors ie unequal weight distribution, joint placement, shoulder width, intersection of what I call "support vectors" with the body depending upon lay angle. I think it can work, and provide a supremely comfortable experience, but it's definitely not one size fits all and I have quite a bit more testing to do to get to a formula I would call in any way reliable. Just looking for other discussion on this, mostly to check my work. I don't think I'm wrong, but I have not yet seen anything like this in any of the hammocks I've been in, and it seems ridiculous to me that someone wouldn't have previously tried to fine tune the level of support across the hammock, given that taken broadly, weight distribution in the human body is very similar from individual to individual.

[G-Rat]

I've had similar thoughts that curved/shaped/asymmetric hammocks 'should' work, but came to the conclusion that there are so many variables that generalizations are of limited use. Variable stretchiness of different fabrics is yet another complication. I will say that I like my SLD Streamliner, but I only if I use a pillow under one leg to avoid hyper-extending the knee.

[hutzelbein]

I have built 23 shaped hammocks and have not managed to come up with a successful design. In order to achieve a truly flat lay, you need to push the fabric apart for example with an air pad. This is basically what the Amok Draumr or the Hammock Bliss Sky Bed do. Those designs have their place - but I greatly prefer breathable underquilts over sweaty pads.

[Blargendarg]

Thank you both for your responses and for listing those designs... I admittedly have been sheltered when it comes to other designs and only have tried or read about a small handful. It's true that there *might* be too much variation between individuals for a general design to be widely successful, and even now I'm looking at it from the perspective of creating a few different models once I can hone in on one that works well for me and the few interested friends and fam, but I'm not giving up yet.

I am VERY good at ripping out seams now, and have a few dozen variations under my belt, though they hardly count as that many completed designs.

I've found that it's not hard to get a dead flat and level lay using a shaped end that works at least for the small height and weight range I have easily available for testing. The issue has been that comfort 'varies independently' - my first flat and level hammock was nearly a torture device - and I've found that allowing higher % of body weight to be carried (and also transitions in amount of support) in certain places works much better than others, esp hips and shoulders.

At first I thought that it needed to be a very shallow contour to work and indeed variations of as little as a quarter inch can make big differences, but when weight is carried in the right areas it allows for a much more dramatic contour. As you might expect, with a design like this, there is a dramatic difference between being in the sweet spot and being just a little bit out of it. So making the sweet spot larger has to be a priority too - nobody wants to have to take a class to figure out how to lay in their hammock.

I also have a couple of design ideas that allow for adjustability to the individual, which eliminates the generalizations, though I haven't gotten around to prototyping them yet. I had thought to use them as a kind of Brannock device that could be used to turn out something tailor made... might be ok as a solution but as for now the construction is complex and not totally settled so who knows. It'd be a lot to go through when most folks are ok with 'pretty flat'. This has all been driven in some respects by my brother's quest. He was in an accident when he was younger and while he fully recovered, as a result he has more particular requirements to sleep through the night in a hammock. I'd like to give him that if I can. And I guess I wouldn't mind it either.

Thanks again. I'll take a look into those designs

[hutzelbein]

Some of my shaped hammocks were more comfortable than others, but I found that using a hammock fabric with the right amount of stretch, and getting the length, width and especially the sag right were a lot more successful. In my experience, people who are unhappy with the gathered end design often simply have not paid enough attention to the other factors. It's like coming to the conclusion that backpacks suck because the only backpack you ever tried didn't fit you very well.