Make Your Own Gear: 5 Yards to SUL, Part 3 - Tarp
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Jay Ham
(jham) - F - M

Locale: Southwest
Re: When can we expect part 4 - making the backpack? on 01/07/2007 18:17:08 MST Print View

Not exactly sure. The editorial staff has it, so it won't be long now.

Jay
MYOG

Pat Rabun
(prabun) - MLife

Locale: Southwest
Re: Re: Re: Make Your Own Gear: 5 Yards to SUL, Part 3 - Tarp on 01/13/2007 17:41:57 MST Print View

Jay,
Nice work! I really want to make the tarp (have the fabric in hand) but I don`t have a tarp with a catenary curve to trace. Anyone have one they could trace on some paper to the correct size and mail to me? I`ll gladly pay for shipping/handling/labor, etc. Thanks
Pat

Drew Davis
(drewnc2005) - F

Locale: Hillsborough, NC
Nylon or polyester grosgrain? on 01/28/2007 16:23:31 MST Print View

Jay,

Is that polyester or nylon grosgrain? Is one better than the other?

Drew

Frank Ramos
(frprovis) - F
Re: Nylon or polyester grosgrain? on 01/28/2007 19:25:12 MST Print View

Polypropylene grograin or webbing is normally better then nylon because it absorbs less water, hence dries faster, hence reduces the chance of mildew. For the same reason, guy lines should be polyester. The only reason I can think of using nylon grosgrain or webbing is because you plan to abuse the pullouts, such as by pounding stakes into the ground with a rock while the stakes are inserted in the pullouts--there is a good chance the rock will hit the pullout fabric and cut it and nylon is much more durable than polypropylene. But this is a bone-headed move to begin with, since there is also the possibility of slipping and cutting the silnylon.

To give some idea of the importance of fast-drying pull-out loops, this is the only part of one of my old Outdoor Research bivy sacks that ever mildewed. The Goretex top and coated nylon bottom dried fairly quickly, but the pullouts seemed to take forever to dry. On cloudy days, I just gave up waiting and the result was mildew.

As for the all this hoopla about catenary curves, I hope everyone is aware that all nylons stretch, especially when wet (such as from condensation or rain) and thus a catenary curve is of limited importance with tarps. Far more important, in my experience, is strong reinforcing at the pull-outs, so you can really tighten things up, especially on the ridgeline. In my opinion, merely stitching a reinforcement patch is insufficient. Far better is to glue a reinforcement patch to the tarp using Silnet seam-sealer. Not only does the glue itself reinforce the tarp, but the glue evenly distributes the forces across the entire area covered by the reinforcement patch, whereas stitching distributes the forces to only the line of stitching. I once ripped out the ridge-seam pullout of an Integral Designs SilShelter while trying to tauten things up.

In any case, mathematical catenary curves are misleading. What you are really trying to do is compensate for fabric stretch, which is different with the grain, against the grain, and diagonal to the grain. This has nothing to do with mathematical catenary formulas, however it turns out that the mathematical catenary formula gives a decent enough approximation in practice. Technically, the correct approach is to pull on the tarp fabric at the points where you would be putting the pullouts and then see how the fabric stretches and wrinkles, and then cut out some of the wrinkled area. Because of the margin for error associated with cutting fabric, especially by hand, any smooth curve is going to work--catenary, parabolic, whatever--as long as you don't cut too much off.

Daniel Benthal
(DBthal)

Locale: Mid-Coast Maine
Things Learned on 01/28/2007 19:48:17 MST Print View

I sewed my first tarp two weeks ago using information from Jay Ham's article and other postings on BPL. Here's some things I learned.

I agree it is best to "glue" reinforcement patches of silnylon at the pull outs. I found it best to use masking tape to outline the patch on the body of the tarp, put on a THIN coat of silicone, and then scrape off as much as possible before applying the reinforcement patch. Cover with wax paper and put a book on top while it dries. I did sew around the edge of the patch once dry.

My 1# learning was how to keep the silnylon moving evenly past the feed dogs to keep an even stitch. I learned that tissue paper (like in a gift box) cut in strips as backing allowed the feed dogs to feed the fabric evenly. I purchased a pack of tissue paper from Walmart for 99 cents. I cut 2" wide strips of the tissue paper and placed it between the feed dogs and the silnylon. This worked GREAT. It is easy to tear off the tissue paper along the perforations caused by the stitch.

Finally, I agree with Jay's experience that it is not necessary to pin or otherwise secure seams in place before sewing. Simply mark the seam edge on the fabric with a Sharpie, and then fold it in place by hand. If you sew about 6" lengths at a time it is easier to sew a hand folded seam then to "pin" it.

There were a few rookie mistakes in my tarp, but overall it came out great and is customized to my design.

Dan

Edited by DBthal on 01/28/2007 20:05:39 MST.

Sam Haraldson
(sharalds) - MLife

Locale: Gallatin Range
Make Your Own Gear: 5 Yards to SUL, Part 3 - Tarp on 03/22/2007 16:33:43 MDT Print View

Okay, everything has been going along fine thus far. I've cut the pieces, sewed the ridgeline and am ready to attach the beaks.

I opted to make the ridgeline of my version longer than the pattern called for. In doing so it made the angle of the beak pieces are different than the original pattern. I'm worried that if I sew the beaks on now there will be slack fabric in them when the tarp is pulled taut.

Tarp Question Diagram

In the diagram I drew above, if I was to flip Part A over and then slide it under Part B do the red and green lines need to match up? The pieces I have currently do not line up in that fashion which is what leads me to believe there would be tautness issues.

Comments please as I'm not spatially thoughtful enough to imagine this in my head and I had trouble getting my CAD program to extrude these shapes.

Edited by sharalds on 03/22/2007 16:36:07 MDT.

Sam Haraldson
(sharalds) - MLife

Locale: Gallatin Range
Make Your Own Gear: 5 Yards to SUL, Part 3 - Tarp on 03/24/2007 11:19:14 MDT Print View

*bump*

Daniel Benthal
(DBthal)

Locale: Mid-Coast Maine
Beak on 03/24/2007 12:15:39 MDT Print View

Sam,

Try using clothes pins to "attach" the beak to the tarp body and see how it looks. Hold the tarp up as if pitched.

Worth a try.

Sam Haraldson
(sharalds) - MLife

Locale: Gallatin Range
Make Your Own Gear: 5 Yards to SUL, Part 3 - Tarp on 03/24/2007 12:34:22 MDT Print View

Worth a try maybe. We're talking about Spinn fabric here and I don't want to put any holes in it. I'll see if I can find some clothes pins maybe as I know that duct tape won't stick to it. I appreciate your suggestion.

Benjamin Smith
(bugbomb) - F - M

Locale: South Texas
Re: Make Your Own Gear: 5 Yards to SUL, Part 3 - Tarp on 03/24/2007 15:40:49 MDT Print View

Sam,

I can't tell for sure from looking at your pictures, but I think you're going to want the other edge of the beak attached to the tarp. I made a similar tarp, though with a less dramatic ridgeline extension. On mine, it was plain that the longer edge (i.e., not at right angles to the ridgeline) of the beak needed to be on the bottom, facing the ground. But if you're not sure I'd either pin/secure it like suggested before OR mock it up with butcher paper or cardboard, even if in smaller scale. I've done that with other projects, and it always pays off.

Pictures are mandatory when you're finished!

Sam Haraldson
(sharalds) - MLife

Locale: Gallatin Range
Make Your Own Gear: 5 Yards to SUL, Part 3 - Tarp on 03/25/2007 12:05:08 MDT Print View

Ben,


the photo I used was taken by Jay Hamm and is from the original article. I'm familiar with how the two pieces sew together, what I'm unsure of is whether or not I've cut the angle of the long side properly. Thanks though.

- sam_h

Sam Haraldson
(sharalds) - MLife

Locale: Gallatin Range
Make Your Own Gear: 5 Yards to SUL, Part 3 - Tarp on 05/30/2007 22:29:25 MDT Print View

After a good long while of putting this project on hold my tarp is very near completion after a four hour sewing session this evening. I just need to attach 9 of the 10 tie-outs and it'll be good to go. I should be able to put those on tomorrow afternoon and maybe even get it outside for some testing and photos. Oh joy!

Jay Ham
(jham) - F - M

Locale: Southwest
Re: Make Your Own Gear: 5 Yards to SUL, Part 3 - Tarp on 05/31/2007 22:39:11 MDT Print View

Great Sam! I can't wait to hear how it turns out. Pictures!

Jay
MYOG

Sam Haraldson
(sharalds) - MLife

Locale: Gallatin Range
Make Your Own Gear: 5 Yards to SUL, Part 3 - Tarp on 06/01/2007 11:58:02 MDT Print View

Absolutely, Jay. I finished it at around 11pm last night and - get this - I was so excited I took it down to my local park (in the rain nonetheless) and set it up for the first time.

I'm very happy with my handi-work. Everything pitches tight, it looks nice and provides ample room. I made a couple design changes to mine for comfort. The ridgeline on mine ended up at around 86".

I am a bit let-down by something I simply couldn't envision however. I questioned about it in this thread but wasn't able to come up with an answer however. I won't try and describe the situation until I have a photo to go along with it.

Overall I'm quite pleased with the final product (once I tweak the aforementioend situation) and am excited to pitch up really taut to see if it's durable. I will probably also add tie-outs to the middle of the side-panels to keep them from pushing inward during heavy wind or light snow.

Sam Haraldson
(sharalds) - MLife

Locale: Gallatin Range
Make Your Own Gear: 5 Yards to SUL, Part 3 - Tarp on 06/02/2007 18:47:18 MDT Print View













Edited by sharalds on 06/02/2007 18:52:23 MDT.

Sam Haraldson
(sharalds) - MLife

Locale: Gallatin Range
Make Your Own Gear: 5 Yards to SUL, Part 3 - Tarp on 06/02/2007 18:56:13 MDT Print View

Okay, there's the pictures. Now I need some honest opinions.

1.) Will putting the trekking pole up inside the beak cause too much wear on the spinnaker fabric? The poles are Black Diamond Alpine CFs with a soft rubbery top to the pole. Should I consider draping the stuff sack over the top of the pole or anything like that?

2.) What are folks opinions on my bar-tacks for the side tie-outs? The stitch pattern isn't very tight (compared to say Mountain Laurel Designs which uses a pretty tight bartack).

3.) Note the rear beak isn't even tied out in my photos. The angle I came up with for the rear beak only pulls out from the tarps dripline an inch or two so I don't even know if pulling it taut is worth the weight of a guyline back there. What are your thoughts?

Oliver Budack
(Snuffy) - MLife
seam/ stitching on 06/02/2007 20:41:28 MDT Print View

The seam of your webbing/guylines doesnt look that strong.
especially here:http://i149.photobucket.com/albums/s65/stevenqsteve/Spinnaker%20Tarp/spinn_sidetie.jpg

I would sew it twice or even more often. Try to fix start and ending(very low feed motion)
When the seam start to open, due to what reason ever, the rest follow very quickly with your seam.


Oliver

Edited by Snuffy on 06/02/2007 20:46:03 MDT.

Sam Haraldson
(sharalds) - MLife

Locale: Gallatin Range
Make Your Own Gear: 5 Yards to SUL, Part 3 - Tarp on 06/02/2007 20:50:54 MDT Print View

Oliver, thank you for your thoughts. Do you think that putting that many more holes in the fabric will adversely affect the strength, thereby negating the benefits?

Sam Haraldson
(sharalds) - MLife

Locale: Gallatin Range
Advice/Opinions Needed for Newly-sewn Spinn Tarp on 06/05/2007 11:56:11 MDT Print View

Hey folks,

I'm looking for advice and opinions on durability issues related to my tie-out stitches as well as the positioning of the trekking pole against the spinn fabric inside the beak as seen in the photos above.

Thanks,
sam_h

Thierry Bismuth
(thierrybismuth) - M
Gutterman Thread on 09/07/2007 01:45:22 MDT Print View

Jay.
What kind of Gutterman Thread (references) is used for the tarp.
Regards.
Thierry