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Roundtrip Raven
06-22-2017, 09:25
With the return of RSBTR's HyperD XL, it got me thinking about optimizing my fabric order. The advantage of this fabric is the width is continuous, instead of 3 panels sewn into one. I am 5'6" and currently sleep in an 11-foot Chameleon. My question is: How short can I make a hammock made out of HypderD XL AND still achieve a flat lay as an 11' x 58" hammock?

Mathematically to achieve the same amount of area in square inch,

[(11' * 12" * 58") ÷ 74" ] ÷ 12" = 8.621 feet. That sounds incredibly short. My best guess is 10 feet long. What say you gurus?

hutzelbein
06-22-2017, 11:10
If width would work with short hammocks, those "double" parachute hammocks would be supremely comfortable. Truth is, in order to use the width, you need length. Simply take a tea towel, gather it like you would with a hammock - once at the full length, once at the half length. The short tea towel hammock should look a lot more like a bathtub than the long tea towel hammock. This is down to the angles and relations of the lengths to each other. Simplified, you could look at each quarter of the gathered hammock as a set of right-angled triangles. With the same width, the longer the hammock, the closer hypotenuse is in length to the center leg and the flatter the curve the fabric makes.

Example:

With a 108" x 60" hammock, half the hammock length is 54" and half the width is 30". So the largest right-angled triangle that is created when you gather the hammock is 54" x 30" x 44.9"; the smallest "triangle" is just a 54" line (in the center of the hammock). So the fabric has to curve from 44.9" to 54".

With a 144" x 60" hammock, the largest triangle is 72" x 30" x 65.5" while the line in the center is 72". The fabric creates a much flatter curve to go from 65.5" to 72".

With a super long hammock there would be almost no curve. A 1000" x 60" hammock would have a ratio of 499" to 500"!

If 11' feels good, stick with the length. Yes it will weigh a bit more, but I think the added comfort is worth it :)

WhollyHamaca
07-23-2017, 15:34
Thank you, hutzelbein! That is a question I've pondered, too. After I drew the 4-triangles diagram as you described, I can appreciate the elegant geometric clarity of your explanation.

I have a related question that concerns the amount of sag needed for wider hammocks, maybe of particular interest to indoor hangers with Brazilian or very wide gathered-end hammocks. For example, given two 144" long gathered end hammocks, we can use your geometric model to explain why a 90" wide hammock can have high, tight clamshell or bathtub sides, while a 60" wide hammock with the same fixed ridgeline (or hooks in walls, etc) does not. The ratio between the long leg of the largest possible triangle and its hypotenuse clearly is much less for the wider hammock than for the narrower one (in this example that ratio is 0.78 vs. 0.91 if my math is correct), which helps to explain the deeper curvature across the wider hammock, but doesn't (I think) entirely explain its high, tight bathtub sides.

I have high regard for the Ultimate Hang calculator as a fine and useful tool for most camping-width hammocks, but in my limited experience it doesn't work as well for wide gathered-end or Brazilians. I know 45* is often cited by sellers as a rule of thumb for Brazilians or Mayans, but I wonder how we can describe geometrically the degree of sag needed to alleviate high, tight sides in relation to a particular hammock's length and width?