OR - DIY Cuben Fiber Tarp - joe schaffer

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DIY Cuben Fiber Tarp


Owner Review by Joe Schaffer
June 8, 2016


REVIEWER INFORMATION: 
NAME: Joe Schaffer
EMAIL: never2muchstuff(at)yahoo(dot)com
AGE: 68
GENDER: Male
HEIGHT: 5 ft 9 in (1.75 m)
WEIGHT: 175 lb (79.4 kg)
HOME:  Bay Area, California USA

     I started at 11 as a deprived minimalist base camper, growing comfort pounds until the weight became unbearable. Now I lug comfort in a more prudent application of lighter stuff, striking camp daily for 5 mi / 8 k gambits over as much XC granite as I can route. Leave weight is 40 lb (18 kg) for 3-10 days. I snow base camp 2-3 times a year a mile (1.5 km) or so from the car with 50 lb (23 kg) for 2-3 nights. I’m out every month; 85 nights a year; 1/3 solo; mostly CA Sierras 7,000-9,000 ft (2,100-2,700 m).

Gear: Homemade tarp

Specs:   
   Primary Material: 0.51 oz sq yd (17.4 g sq m) cuben fiber 
   Secondary Materials: nylon taffeta, double-sided tape, thread, grommets
   Cut length: 10 ft (3.05 m) 
   Cut width: 9 ft (2.74 m)
   Finished weight: 7.6 oz (215 g)
   Shown folded to: 9 x 4 1/2 x 2 in (23 x 11 x 5 cm) 

Tools:
    Sewing machine
    Grommet kit 
    Scissors    

Cost: about $250 US

Description: 
   This multi-purpose tarp was made to match the pole tips of the pictured tent, but is otherwise a standard tarp that can be strung length-wise or width-wise. It has 8 grommets; two of which clothesline the tarp; 4 peg the corners; and 2 peg the center as necessary. Twelve clam-biting taped-on loops using cuben fiber material 3/8 x 4 in (10 x 100 mm) provide additional stabilization points as may be needed for wind. Cuben is sold by (the vendor I got it from) the the roll yard (0.91 m) 54 in (137 cm) wide, so the tarp has a 3/8 in (10 mm) seam running its length; sewn on the first fold of the French seam and double-side-taped on the second fold for additional strength and waterproofing the stitch holes. A sewn 3/8 in (10 mm) hem finishes the perimeter edge. Grommet points are reinforced in a triangular clam bite of nylon taffeta folded in and sewn with the hem. This model of cuben fiber is waterproof, not breathable. It field-folds easily to about the size of a 1-liter (1 qt) flask. It could probably squeeze into a 22 oz (.65 L) mug, but I wouldn't want to roll it that tightly on ground with pointy objects. The size dimensions equal the raw cut size, which seems consistent with the way polyethlene tarps are marketed.
        
DIY Impressions:
    Cuben is very easy to work with, especially compared to materials like sil-nylon and uncoated nylon. It has no loose threads and seams press flat and stay in place, though I did use cello tape holders sparingly. (Eventually I figured out that doubling one end back on the cello tape before sticking it on made the tape much easier to get off.) I used poly-cotton thread as recommended by the fabric vendor, and a #9 needle that was a size or so smaller than recommended but worked well. I practiced on stuff sacks to get the tension correct and thereafter had no problems. I can figure out how to turn on the sewing machine, and that pretty well reaches the limit of my expertise. I'm satisfied with the result, so I would think anyone could do this. Cuben comes with a margin of clear film and I couldn't find a sharp enough pair of scissors to trim it off cleanly, quickly or easily. As advised by the vendor, the tape used is unforgiving to say the least, yielding only great confidence that it will not soon forego its duty. 

    I wanted to see if I could make this simple project as a test whether to venture toward more difficult ones. Otherwise, given the necessity of buying more tape than necessary and requiring a grommet kit and scraps of nylon, it would make more sense to buy it already made. 

    The weight shown does not include the clothesline or pegs, both of which I would be carrying anyway. It also does not include stretch cord loops to affix the tarp at the four pole tip points, and they add 0.4 oz (11 g).

    Waterproof cuben comes in 3 weights. Though I haven't the other two for direct comparison, I think medium best for a tarp. The lighter choice would save about 1.7 oz (48 g) on this size tarp, but I gravitated toward stronger and more durable. The heavy grade seemed overkill for this application. The vendor I bought from offers green and blue. I like blue sky and green stuff under it.

Field Conditions:
    May 15: Tahoe National Forest, CA. 6,800 ft (2,070 m) Chilly, showers, drizzle, hail, sleet, gusty.

Field Impressions:
    I like tarps. For many years I used a cheap tarp over a cheap tent and was happy enough until I had to get lighter at about the same time I started camping in granite where suitable anchors do not always grow near a flat spot. It hadn't previously occurred to me to modify the tarp to fit the pole tips. This tarp is light, stows small and requires only two critical (clothesline) anchors. I found that in a pinch it would even be possible to get by without those, so my full-fly days are pretty much over. The tarp is less convenient, but provides almost as much weather protection as a full fly at about a third of the weight and bulk. I strung up the tarp first and then erected the tent under it, which worked even better in the rain for a dry pitch than a loose fly.

     Cuben likes to stay folded, and is so light it isn't easy to shake out in the wind and rain. It doesn't saturate, and stays taut when wet with no shrinking as it dries. I loop the clothesline through the grommets to put most pressure on the line and just enough on the tarp to keep it taut. This takes patience as nylon line stretches. It would be easier to tie off at each side in separate pieces of line, but that puts a lot of pre-stress on the fabric (and seam) and leaves less margin for withstanding wind gusts. The translucent material lets through a lot of light, which I find preferable on dark and stormy occasions. 

    I'm reluctant (to the point of refusing) to test the puncture resistance of the material, but my feeling is that it probably has less than coated nylon and more than polyethlene. Unlike poly, it doesn't seem to "weaken" on crush lines. I'm thinking it needs to be treated as carefully as sil-nylon to avoid scuffing. I won't know unless it happens whether mold can develop between the layers. I haven't noticed any odor of mildew or chemicals. I am careful to make sure the tarp is upwind from fire and out of cinder range.

    I cannot overlook that this DIY tarp shelters no better and costs 30 times polyethlene off the shelf. I rationalize it for the benefit of saving weight directly, and indirectly in contributing to being able to take a smaller volume (lighter) pack. In fact, I regard it as a small price to pay for helping me continue an activity that the aging body might like to see more in pictures. I'm pleased to the point of already noodling my next cuben project, a poncho to double as a tarp over a solo tent.

Quick shots:
    a) light
    b) small
    c) $$$$