Welcome! Ultralight backpacking is my passion, and keeping up on new technologies, gear, and techniques relevant to UL backpacking is what floats my boat. I'm always looking for the lightest, most functional gear to improve a lightweight or ultralight backpacking kit, and report my impressions and field testing results here. For hikers wanting to keep up on the latest and greatest ultralight backpacking gear, this is a good place to hang out. Also, there is a lot of information here (and on our informational website Southwest Ultralight Backpacking) on useful techniques and backcountry etiquette -- food for thought for hikers wanting to lighten their load and their impacts.

My goal for Ultralight Insights is to understand, test, and report on new technologies and gear of interest to lightweight and ultralight backpackers. It's a passion after all, so we just plain enjoy talking about it. I hope readers will add their own wisdom and comments, respond to my questions, ask their own questions, and correct me if I get something wrong. Happy hiking! Will

Wednesday, March 21, 2012

Make a Lightweight, Durable, Inexpensive Groundsheet or Bivy

By Will Rietveld

What you use for a groundsheet under your shelter or under your sleeping bag depends on the ground surface.

If the ground is fairly smooth and you use a groundsheet mainly to keep your gear clean, the Gossamer Gear Polycryo Ground Cloth is ideal because it’s very tough and very lightweight. No need to look any further.

For a bomber groundsheet, many hikers use conventional Tyvek housewrap, and there are places on the Web where you can purchase it piecemeal. It’s very durable, and will soften with a few trips through the wash machine, but it’s a bit on the heavy side.

A better option is Type 1443R Tyvek, which is a lighter, softer version used in Tyvek clothing. It’s inexpensive, weighs about the same as silnylon, and its waterproof like other Tyvek. It costs about $3.50 a yard (60 inches wide) at stores that sell kite-making supplies, like Into The Wind. Since it’s breathable, some people argue that it’s not waterproof, but I have yet to have a problem with water passing through it, even when camping on wet ground.

 Soft Tyvek (Type 1443R) used as a groundsheet under a Gossamer Gear SpinnTwinn tarp.

The breathability of this Tyvek makes it usable beyond groundsheets. An inexpensive Tyvek bivy works wonderfully for sleeping on the ground under the stars or inside a floorless shelter, and it adds a few degrees of warmth to your sleeping system. It’s very simple to construct a simple bivy by folding a sheet over lengthwise, sewing one end and one side, then turning it inside out. This yields a bivy with a 60-inch girth, which is a bit on the slender side. For a roomier bivy, especially if you put your sleeping pad inside the bivy, you will need to add a strip of Tyvek to the open side.  Adding a 7 inch strip yields a 63-inch girth (the formula is to add 2 inches for each inch of girth you want to add, plus a 1 inch for seam allowances). Type 1443R Tyvek is very easy to sew, or you can tape it with filament or ripstop tape. If you want to seal the seams, use Roo Glue.

1 comment:

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