endo's gear lab: bivy tarp
okay! i want to start writing up some posts about gear experiments, partially to help me think things through and document them, and also to share this process with others.
(and also it's an excuse to make cute doodles)
when i do fair-weather solo motorcycle touring, i often camp out with a bug bivy (basically just a bivy-sack shaped bug netting), sleeping pad, and sleeping bag; i bring the groundcloth from my two-person tent that i pitch over the bivy with paracord if i expect light rain, or want some more privacy. the groundcloth is okay as a tarp, but it's a tiny bit too small. commercially-available backpacking tarps tend to be more expensive than i can justify paying for what's basically a rectangle with grommets (they can easily run over $100USD).
make myself a bivy tarp from scratch! i bought myself 58"x4yd of 1.1oz silnylon, an extremely lightweight, water/windproof, strong material that is what a lot of light backpacking gear is made from anyway. total cost, including shipping, was under $25USD.
- reduce cost out of pocket (which excludes time/skill involved in production)
- minimize packaging material (i got fabric shipped to me cut and folded and tucked into a small envelope with no extraneous packaging, whereas commercially-produced gear tend to come with documentation, wrapping, other stuff, etc.)
- learn to work with a material that is new to me, and increase my fabric construction skills
- sewing machine use (it's of course possible to hand-stitch this, but i greatly appreciated being able to throw down several yards of straight hems by machine)
- measuring and cutting fabric (helps to have extremely sharp scissors)
- patience, for working with a difficult material
process so far:
- pitched my bivy, strung paracord along the spine of where i want the tarp to be, fit the tarp over the bivy.
- mark off length, leaving about a 6" overhang on either side
- i wanted the tarp to taper down towards the feet, so i made a diagonal mark from around the shoulders down to the feet, making the overall tarp shape trapezoidal when flat. this was all just eyeballing the shape/length, sometimes folding over the fabric to make the shape i wanted and then marking along the fold.
- cut along marks, leaving about 1.5" for hemming along each edge
- hem cut edges
- silnylon is very slippery! it is literally light nylon embedded with silicone, which means it sticks to nothing. this is great when you want water to bead right off. it's really frustrating when you're trying to lay it out on a table to mark off cuts.
- recommendation: work on the floor, or, put stacks of books or shoes or something on it to keep it from sliding around while you mark off your cts.
- can i say this again? silnylon is very slippery! i'm doing a rolled hem (fold over about 1/2", then fold over again, and stitch that to protect the cut edges), and i didn't want to use needles because i didn't want to introduce more holes, but the hems unroll themselves as soon as i break eye contact with them.
- recommendation: use a glue stick and press the edges together for about ten seconds; this holds the edges together at least until you can feed it through the machine.
- silnylon is also very stretchy!
- recommendation: grab the material on either side of the needle and pull it taught while the machine fed it through.
- attach adjustable cords to the corners for staking
- test-pitch in the yard, checking for sagging points
- consider adding points for guy-lines, maybe a peak reinforcement for an upright support at head or feet