This has to be in the forums, but I couldn't find it. What is the strongest way to create a cuben ridgeline for a tarp? Is it best to tape and sew or just tape?

I am thinking a combination of taped and sewn would be strongest. Do you sew a flat felled seam then place one sided tape on the outside?

I think spinnaker makers use tape to make a lap seam, then sew a row of stitches.

Where the stitches are there are two layer of Cuben and on both sides there is tape holding the two layers together

Also, spinnaker makers uses a triple step zig-zag correct? I don't know how much more strength that will add.

Use hysol and clamp the bond well. Not as convenient as tape but many DIY tests have shown that the bonded/taped seam is usually stronger than the fabric itself. Sewing just introduces stress points that weaken the material. Then seamgrip (ie weight) has to be added to waterproof and repair the weakening caused by needle holes.

You'll notice that MLD (and a few others) have stopped sewing their cuben ridgelines and they tend to know what they're doing. While sailmakers may still sew, they're dealing with much larger panels with higher shock stresses (the zig zag stitches help add some stretch) than a tarp or tent sees.

John, there are many threads about this in the MYOG forum. It might take some digging to find them, but they have a lot of good information.

In my opinion, bonding with a liquid adhesive (Loctite Hysol U09FL and U09LV, or one of several contact adhesives) gives the strongest seams in cuben. Sewing and taping are used by cottage manufacturers and some in the MYOG crowd because they are quicker and less laborious. Many tarps with sewn and/or taped seams perform beautifully, however, and prove to be durable.

Does anyone know how to bond cat curves and get them nice and smooth? I don't see how they can be weighted unless you put them in a kind of bow shaped mould. Then a strip of cubed is taped over the bonded seam for reenforcement. Again, the cat curve will not lie flat on a table, so how this is done so neatly fascinates me. I have heard that hysol cures very slowly, so the creases can be smoothed out by hand over the course of a day. Has anyone done a pure bonded cat curve like MLD?
Matt

If you used tape, you could just mark a line on each piece of fabric, put tape on one piece of fabric centered on the line, and then attach the other piece of fabric so the lines exactly match up.

They say that since Cuben doesn't stretch it has to be laid out perfectly, and this would make this possible. This may be more important than the small improvement in strength you get with Hysol over tape.

I haven't done this (yet?) so take it for what you wish : )

Thanks for all of the advice. I have a strong preference for taping rather than gluing due to mess and ease of installation. I also don't have the clamps. Based on the sewing needle comments, i'm thinking of a simple lap seam with two sided tape. Has anyone done this? Does it hold up?

John, I have done catenary ridgeline seams in cuben with Hysol. I have found two methods that seem to work. If you decide to try it, let me know and I can tell you about what worked for me.

Thanks Colin. i found this thread http://www.backpackinglight.com/cgi-bin/backpackinglight/forums/thread_display.html?forum_thread_id=39693&disable_pagination=1 that says a lap seam with two sided tape works and the seam can be reinforced with single sided tape. In addition, Lawson's walk through on taping a cat curve is excellent.

This looks hard to beat for simplicity.