Cuben Tarp Questions

[Chris M]

I am about ready to pull the trigger on a cuben flat tarp using the .75oz cuben.

I have a few design thoughts I am working out though.

I am currently planning an 8.5'x8.5' tarp. This would mean I cut two panel pieces that are about 8'8"x 4'4 1/2". I just measured my cuben and the "usable" width is about 54.5". That is the width of the fabric with actual strength, not just the excess film on the sides.

So I am currently looking to use 52.5" of the 54.5" available to me. One thought I had was that I could actually use some of the excess film as the part I roll under for my side hems though. Is this how people normally use this fabric, or is every cutting off the excess width completely? It would be completely hidden inside of the rolled hem of course, but I wasn't sure if people have previously had bad experiences with this?

Another question is how people are preferring to do their tieouts. I was thinking that with the last 2" I have left over in my width, I could create 1" wide cuben bonded tieouts instead of using thinner webbing or grosgrain. I kind of like this idea simply because it is leaving less of the fabric wasted. And with how expensive it is, I don't want to waste anything.If it turns out bonded tieouts aren't a great idea, I could just make the tarp bigger, but adding 4" to the size seems excessive.

I'm excited to hear back from others and get started on this project. Should make for an amazing tarp.

[Colin Krusor]

"One thought I had was that I could actually use some of the excess film as the part I roll under for my side hems though."

You say "excess film". I assume you mean the 2" of excess useable material (laminate including both the film and the reinforcement). I hem my cuben shelters by folding over about 1/2" of material at the edge. What other options were you considering for the hem? Folding over a separate 1" wide piece along the edge?

If you had technical questions about the design or fabrication I could try to answer them, but your questions are about use of the material. That's your decision. If you have enough extra cuben for corner reinforcements and tie-outs, it seems simpler to me to use full-width (54.5") panels. With 0.75 oz/yd cuben, the four inches of extra width will add a total of 0.236 ounces (6.7 grams) to the weight of the tarp.

I would highly recommend reinforcement patches at the corners and anywhere there will be tie-outs attached. I have always preferred to make the tie-outs out of elaborately-reinforced strips of cuben, but others have success with sewn-on grosgrain.

Will you be sewing, taping, or gluing this tarp?

Posting simple diagrams of your design ideas will help people to give relevant feedback.

[Chris M]

Thanks for the response. I have been sick this week, and I have noticed that I don't make as much sense as I would like.

The excess I am talking about is the sides without any reinforcement, just film. I would roll this .5" and then again .5" to create the rolled hem on the sides. The first .5" would be film without reinforcement, and the second .5" would have reinforcement. This would hide the non-reinforced film between usable fabric. I was curious if others had done this

For construction, I plan to sew the side hems and will be glueing the remainder. I plan to use bonded reinforcement patches for the tieouts by cutting out 6" diameter circles. Using quarters on the corners, halves on the sides and the whole circle (possibly a smaller circle) for mid panel tieouts. I have read your past posts on bonding long seams and plan to follow the same steps you have since your results seem so good.

What kind of bonded tieouts are you generally using?

[Steve B]

If you haven't already, check out my tarp design/method at http://www.backpackinglight.com/cgi-bin/backpackinglight/forums/thread_display.html?forum_thread_id=75909

I would cut the film only portion off completely. Only roll reinforced material. I would fold over 1/4", apply 1/2" tape from the crease inwards, fold over along the crease, then fold again. This would form a 1/4" wide rolled hem, IMO stronger than a 1/2" wide hem (even though you use the same amount of material).

I highly recommend the method I went into in the above thread. In order for the tiout to rip out, either multiple strips of fabric have to break or the adhesive has to pull from multiple strips of fabric.

Steve

[Colin Krusor]

Yes, Stephen's method seems like a good one. It seems well thought-out and it is one of the most creative tie-out designs I've seen on a MYOG cuben tarp.

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