DIY Sil-Poly Hex Tarp with Two-Way Tie-Outs

[Uncaged]

This picture is very helpful. Thank you!


Ever consider skipping the grosgrain over the top and capturing a cord in the tube on top? You could splice a loop on each and skip the rings.

Would it still keep out the water without seam sealing?

[kitsapcowboy]

Would it still keep out the water without seam sealing?

Adding the grosgrain adds strength to the ridge line as well as waterproofing, so for myself I see these two primary advantages outweighing anything I'd get by skipping it in favor of the cord method you described. YMMV.

[P-Dub]

I remain somewhat confused by this. How does sewing grosgrain on top of the ridgeline seam keep it from leaking? Aren't you simply making another 2 rows of holes in the tarp by stitching the grosgrain on??

[kitsapcowboy]

I remain somewhat confused by this. How does sewing grosgrain on top of the ridgeline seam keep it from leaking? Aren't you simply making another 2 rows of holes in the tarp by stitching the grosgrain on??

Water is, of course, a liquid, which exhibits proterties of both cohesion and adhesion; it sticks to itself and to other materials as it follows the path of least resistance. As I have come to understand the principles behind the method and observed them in practice on several hammock tarps, by stitching folded grosgrain to the standing (vertical) French seam closely to its second capturing seam so that it is overlapped by the edge of the ribbon, that ribbon edge acts something like a course of roof shingles installed above another. A shingle roof is made up of many individual solid pieces and is full of seams, yet when properly constructed it is functionally watertight because it resists the collection and penetration of rainfall while promoting shedding in a particular direction. The folded grosgrain over the standing seam does all the same things, discouraging water from collecting on a seam that it would otherwise try to penetrate.

(You are not really making an extra row of holes in "the tarp" material per se, but rather in the vertical tab running along the ridge line, so water that would permeate the fabric through the holes made by attaching the ribbon to the ridge line still remains outside the tarp for practical purposes.)

[Winnie]

A close-up photo of the bottom edge of your ridgeline seam might help.

[jellyfish]

Water is, of course, a liquid, which exhibits proterties of both cohesion and adhesion; it sticks to itself and to other materials as it follows the path of least resistance. As I have come to understand the principles behind the method and observed them in practice on several hammock tarps, by stitching folded grosgrain to the standing (vertical) French seam closely to its second capturing seam so that it is overlapped by the edge of the ribbon, that ribbon edge acts something like a course of roof shingles installed above another. A shingle roof is made up of many individual solid pieces and is full of seams, yet when properly constructed it is functionally watertight because it resists the collection and penetration of rainfall while promoting shedding in a particular direction. The folded grosgrain over the standing seam does all the same things, discouraging water from collecting on a seam that it would otherwise try to penetrate.

(You are not really making an extra row of holes in "the tarp" material per se, but rather in the vertical tab running along the ridge line, so water that would permeate the fabric through the holes made by attaching the ribbon to the ridge line still remains outside the tarp for practical purposes.)

Essentially, is it a long dripline?

[kitsapcowboy]

Essentially, is it a long dripline?

To me it functions more like a fabric seam seal; it eliminates (or at least greatly reduces) the opportunity for rainwater to collect on the row of stitches at the bottom of the standing seam (creating hydrostatic pressure) and penetrate it.

[Uncaged]

It took me a while to understand this ridgeline method. However, after reading enough of Kitsapcowboy's posts and a few others including one from Kyle at RBTB, I finally understand what was being described.

Perhaps I can offer two images to help clarify. The first is from Kitsapcowboy's post DIY Xenon Wide Winter Tarp. It was the one that finally made the construction clear in my head.

The second is a sketch of my own. It is more of a schematic diagram than a scale model. (Apparently, I don't know how to make the image bigger inline, so click on it to see it enlarged. Sorry about that.)

Standing seam-Model 3.jpg

Anyway, the basic idea is that the grosgrain folds over the top as a cap. This blocks the water that may otherwise seep between the two halves of the tarp fabric (however unlikely that may be). By having the ribbon extend past the 2nd row of stitching on the French seam, it covers that thread and holes. That row has the potential of allowing water to seep right through to the inside of the tarp as it is the beginning of the angle of the tarp roof. And due to the tension on the tarp body, those holes may get a little larger. The grosgrain cap sheds water past both rows. The stitching that holds the ribbon is above the 2nd row and doesn't have the same tension that would elongate the holes. Water is less likely to get inside the tarp and seam that way. And although it is possible it could, the holes and stitching go straight through to the other side, rather than opening into the inside of the tarp.

Hopefully, this makes as much sense to you as it does in my head.

[jellyfish]

What size line can you use through those linelocks? Will zing-it work?

[kitsapcowboy]

What size line can you use through those linelocks? Will zing-it work?

Zing-It i(1.75mm) s a little small and kind of slippery; the LineLoc 3s seem to work best with various types of utility cord between 2mm and 3mm that have a more conventional woven sheath.