[pct-l] Tarp camping: catenary vs rectangle

[Jim Marco]

Andrew,
	Tarps all provide a roof over your head.
	The catenary cut models simply pitch a bit tighter due to the curves. Tension at the guy-outs and ridge line pulls the fabric tighter. Note that this implies a single pitch, usually an A-frame, or "pup" tent pitch. They are not real effective with cuben, because cuben does not stretch much. Because of this you can get pretty severe wind hammer on the stakes, too. There is no gradual tightening at the stake, simply a fast jerk. I usually think of a "shaped" tarp when someone mentions a cat-cut tarp.
	Square cut tarps, by nature, are not catenary cut. They have a LARGE variety of pitching options. There is a good beginners resource at: http://www.equipped.org/tarp-shelters.htm Square or nearly square tarps work. Rectangles work as well, really. These are usually more flexible, as far as where you set them up and in what pitch. Either cuben or silnylon is used, sometimes other stuff, like plastic, tyvek, spinnaker, Mylar, etc. These are subject to bad wind hammer in some pitches.
	Wind hammer can be relieved by attaching elastic to the guy lines. I usually use heavy duty hair ties. Anything that will stretch a bit before allowing loads to reach the stake softens the hammer.
	I attach the guy lines directly to the tarp. Then simply stake them down. Within 8-12 inches, where doesn't really matter, but ideally you want them pointed at the opposite corner...45 degrees for a square tarp, somewhat variable for a rectangular one.
	Sorry about not mentioning manufacturers. I usually make tarps up. A center doubled, felled seam provides strength along any ridge line...make sure it is seam sealed. Then at least one more loop at the center of all the edges for smaller tarps, two for larger ones. Oware, Equinox, Z-Packs make good tarps. I like the lightest fabric I can get. Usually 1.1oz silnylon, but I have worked with cuben. Cuben is a pain to work with, since it requires glue tape, and, sewing. When all is said and dine it is about 1/2 the weight of silnylon, though. My total weight for a shelter is 14oz that has excellent weather resistance. I could save another 3-5oz on the material (I was including stakes and line) but do not care at this point. For the dollar difference(about 4x as much,) I ignore it. Home made costs about $60, for everything. Cuben would cost about 220 for everything and do no better job, just be lighter at around 8oz for the basic tarp, around 10oz packed, counting stakes and line. If you don't mind the extra dollars, Zpacks offers a fairly good selection here: http://www.zpacks.com/shelter/tarps.shtml  Highly recommended is the 8.5x11.
	My thoughts only . . .  
		jdm  
-----Original Message-----
From: pct-l-bounces at backcountry.net [mailto:pct-l-bounces at backcountry.net] On Behalf Of Andy Martin
Sent: Monday, November 11, 2013 4:22 PM
To: PCT-L
Subject: [pct-l] Tarp camping: catenary vs rectangle

After finishing the PCT this year, I believe that I will be happier carrying and camping with a tarp rather than my tent. Right now I am leaning towards the Mountain Laurel Design Grace Tarp Cuben Fiber Duo. my only reservation is the versatility of pitching a rectangle tarp vs a catenary tarp, though it seams like there would still be lots of options with a cat tarp. would anyone care to discuss the pros and cons of the 2 types, and who your favorite tarp builders are.

Thanks
P-Limp
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