Tie Out Strength Tested by Oware

[Ben Wortman]

I hope Dave doesn't mind me posting this here. He did a tie out test with silnylon. No reinforcements, just a rolled hem. Failed at 72lbs. It looks like it failed at the stitching of the hem.

At least for me, it seams that 55lbs is plenty strong for a tarp or mid. Especially when you figure you have the force of wind and storms divided by the number of tie outs.

I usually don't reinforce a tie out if it lays on a flat felled seam so the force is applied in line with the seam.

http://blog.owareusa.com/2015/02/27/tie-out-testing-silnylon-72-lbs-and-1mm-dacron-cord-knotted-strength-50lbs/

Thanks for posting the test Dave!

Ben

[Sam Farrington]

Can't imagine making a tie-out without a reinforcement patch. It is so easy with Sil Glue and following the article here on BPL.

Oops, remembered that Roger asked for pictures. Unfortunately, the reinforcement patches were bonded to the inside, and are not visible. Here's a photo anyway:

[Ryan Smith]

Hard to tell from the pic, but looks like the tie out sewing went beyond the hem and into the tarp. I wonder if there would be any difference if the sewing was confined to the hem.

Ryan

[Dave @ Oware]

http://blog.owareusa.com/2015/03/05/tie-out-testing-grommet-in-4-layers-silnylon-vs-unre-enforced-1-webbing/

[Jerry Adams]

Interesting. As expected. Thanks.

My corner tie-outs, which have the biggest load, go through a flat felled seam that ends on the edge. So I go through the several layers of fabric of the flat felled seam, plus the edge seam. Seems pretty strong.

[Jim H]

Maybe tangential, but in the pics of the un-reinforced tieout, the top of the Z-stitch is in the hem, but the bottom looks to be interior of them hem, on the main panel. Does the taller Z provide more strength than making a shorter Z which fits on the hem completely?

[Jerry Adams]

I just use a zigzag and try to get all the holes going through three layers of fabric of the hem. Not a bar tack where the holes are too close to each other. No hole should be within 1 mm of another hole.

[Dave @ Oware]

It is stronger to stitch above the hem.

Notice this one where the hem stitching failed on one side while the stitching that went beyond the hem held on the other side.

http://blog.owareusa.com/2015/03/05/grommet-in-webbing-vs-sewn-loop-for-tarp-tie-out/

[Mole J]

Hi David,

I saw your blog post (from the OP) yesterday. I wondered about the stitching.

Can you explain why it is stronger?

I'm interested in the strength of tie-outs stitched solely in the hem versus the type in your first test. I'm not disagreeing with the your statement that it is stronger, (how can I argue with your experience?) but it seems counter intuitive at first glance.

Have you done/could you do a comparison?

The grommet test isn't quite the same thing?

(Tie outs I have made into unreinforced hems have been done with 2 lines of close zigzags into just the rolled hem. They have proved adequate so far….)

[Dave @ Oware]

If all your stitching is within the hem, all the force of the pull is transferred to the single row of stitching of the hem.

zigzag stitches may be another thing to test tho. They may be better or worse?

[Mole J]

I see – makes sense. Thanks

[Dave @ Oware]

http://blog.owareusa.com

[Jerry Adams]

interesting "Z" holds better than bartack

what if you did a loose "bartack" or maybe call it a zigzag?

where all holes in the silnylon are at least 1 mm apart

[Dave @ Oware]

I no longer have a zig zag machine. If you have one, perhaps you could do a test?

[Jerry Adams]

me and my big mouth…

[J-L]

I use the "x-box" for tie-outs. Maybe a "Z" would be sufficient. They both seem to be stronger than bartacks

[Dave @ Oware]

Anything that spreads out the force on a larger area should increase strength up to a point. So a box x should do that. Other things like stiffeners or washers, double layer reinforcements etc. can do it also.

The stretch of the nylon helps a lot too. A non stretch fabric like cuben fiber or polyester might take other extra measures (gluing, reinforcement patches, wider webbing etc) to spread the force out.

Bartacks are useful when you are fastening very sturdy materials together and want to do so in a small neat space, say two pieces of heavy webbing. Directions the stitches run has bearing too. The box x excels in situations where forces run in 4 directions (picture a cargo net).

[Daryl and Daryl]

David,

"Bartacks are useful when you are fastening very sturdy materials together and want to do so in a small neat space, say two pieces of heavy webbing."

The link below supports this. Scroll down the link until you come to a discussion of webbing with bartacks vs X stitching.

here

[Jerry Adams]

Good link Daryl

They were mostly just testing rope/webbing. Didn't test webbing to fabric.

With webbing loop, all the load is concentrated on the end away from the loop so you want lots of stitches close together – several bar tacks on top of each other. Webbing is loose weave so you can have lots of needle holes close together – needle goes through without weakening the webbing.

Sewing two pieces of webbing together easier, because load is concentrated from both ends so all the stitches better share the load.

This is all more relevant to climbing taking falls than tents or packs.

[Daryl and Daryl]

"This is all more relevant to climbing taking falls than tents or packs."

I agree.

[Dave @ Oware]

Follow up note. Unlike has been posted on other blogs, I have always  reinforce tie out points on my shelters on anything bigger than the very smallest tarps (5×8′). Most often on those too, depending on the likely use of the tie point in question.

This test was just for information purposes. For very fragile fabrics, my tests show that a triple rolled hem along with a reinforcement patch also strengthens tie out points that lie on the hem.

[Daryl and Daryl]

Tough to calculate the forces that a tie out might need endure in real life.

A while back I caught my foot in a tent tie-out cord.  My graceful recovery from the snare trap ripped out the tie-out and the horse that it rode in on.

 

[Dave @ Oware]

“Tough to calculate the forces that a tie out might need endure in real life.”

Like three enthusiastic young campers trying out a truckers hitch on the ridge line tie outs.

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