Gear Mod: Ground Sheet for Chair Zero
The Helinox Chair Zero is a really nice ultralight camp chair. At around 18oz, it’s light enough to take on many backcountry adventures and well worth the weight penalty for many. However, the small feet will sink into soft ground and you can really forget about using it sand.
To address this, Helinox does sell a few options, including rubber ball feet and a fabric ground sheet. However, both of these options are heavy and that’s a bit contrary to the design goal of this chair.
So in this mod, I’ll be attempting to create a ground sheet out of light weight Tyvek. The goal is to keep it below an ounce!
For this project, you will need a bit of Tyvek material and sewing supplies. You can get Tyvek from a variety of sources, including your local building supply store. The challenge is finding smaller sheets or plain white sheets if that matters (the stuff from your local Home Depot or Lowe’s is going to have the Dupont logo all over it). You will need a piece about 24″ x 20″. I don’t have an exact template to offer at this time, so consider the instructions below a rough guide.
For the shape, I decided to use some catenary curves to both reduce the amount of material, but also to improve the performance under tension. A catenary curve is simply the shape that is made when you hang a chain from two points. So to create the necessary curves I started with a piece of cardboard, laying out the distances between the outer edges of the feet. I then tacked this up and borrowed one of my wife’s necklaces, draping it over the tacks, like this:
Then, I created a series of “dots” along the curve with a marker and finally connected the dots and cut out my template. I then placed the template on the Tyvek and began sketching out my rough shape.
It took a bit of experimenting to get the shape around the feet right. The idea was to leave enough extra material that I could fold it over and stitch to the sheet to create “pockets” for the feet to slip into. I eventually settled on something about like this:
After cutting out the final shape, I simply folded the ends over and ran a stitch along the edge, tacking the start and end for reinforcement. I made a couple, one with hemmed seams and one without. Adding a hem on these curves is a bit tricky. I wanted to try one with to see if helped at all with durability. I’ll update as I get time testing each.
That’s it. This is a pretty easy project that can be completed in about 30 minutes. And the final weight? 6 grams. Less than 1/4 of an ounce.
Only time will tell if this will be durable to hold up to extended use. Or even temporary use. I have tried it in soft, wet, yard and so far so good. I’ll take it out on a few trips, including to the beach, to see how it holds up to actual use and will update here when I have more data.
If it does not hold up, at only 6 grams, I think I have room to add some sort of reinforcement.