Tell me about Asymetrical tarps

[Passinthru]

I see the advantages of a 'hex' shape, I get the 'diamond' in certain conditions, and of course the square or rectangle makes sense. But what is the reason for the 'asym' ? Also, the term 'asym' seems rather vague - seems it could be almost any shape.
The reason I ask is that I am looking for a smaller, dedicated hammock tarp and have seen a Hennesy on the 'For Sale' forum. But when looking at the Hennesy website they are calling it a 'parallelogram'. Is an 'asym' and a 'parallelogram' one and the same? I think I see the reason for the design if one stayed in one position all night but I flop from side to side and my diagonal lay changes accordingly.
Can anyone enlighten me on the actual shape and benefits of the 'asym' or 'parallelogram'?

[michigandave]

This link shows how the asym tarp is all layed out: http://diygearsupply.com/wp-content/...arp-lowres.jpg . My buddy just bought one from Jared at Simply Light Designs ( http://www.simplylightdesigns.com/ca...products_id/81 ) and I borrowed it over this past weekend to see how it would fit with various hammocks (10' SLD Streamliner and Eno Single) . Depending on how it's pitched, it should keep you dry in a storm. Heavy rain and blowing wind might be a different story.

I like the idea of a asym tarp, because it really gets your weather protection down to a minimum weight. On a trip with a slight or no chance of rain, it would be great. Asym tarps also have a left or right lay, depending on how you set up the hammock, so that's something that you have to be aware of during the setup.

Here's a few pics from the test. Pitched high and low with the Eno and it fit well. I tried my longer (10' ) one and it was a little tight for coverage on the ends.

[dakotaross]

Asym tarps are for lying in one direction. One side covers your head better, other side covers feet better. Technically still have coverage over all of you, just a little better in those areas to stay dry and yet have minimal tarp weight. If you switch around the direction of your lay, then don't bother with them. Today's materials kinda negate the weight benefit unless you're UL.

Parallelogram just means straight perpendicular sides - so the assymetrical term is a little bit of a misnomer. A square or rectangular tarp is also a parallelogram. An asym parallelogram tarp is one where the cut of the angles are not 90 degrees and the ridgeline is the long diagonal, with the other "corners" staked out to the sides. Whereas a symmetrical diamond tarp would have the sides staked in exactly the same location on opposite sides, the asym tarp corners are staked with one being closer to one end of the hammock and the other closer to the other end.

[nothermark]

One also needs to look at the asymmetrical tarp probably first came to notice with the Hennessy asymmetrical hammock. I suspect at least part of it is to put the stress on the cloth as a bias instead of linear to the weave.

[Passinthru]

This is all very helpful. It confirms what I thought I knew about geometry and tarp pitching. I can now rule out anything called 'asymmetrical' in my tarp search.

[PDA]

Asym type is easiest to make, and is the lightest to give "adequate" coverage. Made from one piece of 5' wide fabric - nocentral seam. Light weight essential for adventure racers,not important for campers. here's a page showing material use
http://diygearsupply.com/diy-guides/tarps/

There is a sticky above comparing different types