tie-out ripped

[Jerry Adams]

I have a MYOG mid with RSBTR silnylon (0.93 oz/yd2).

Wind was 30 MPH according to my Brunton ADC Wind

Corner tie-out ripped off:

The flat felled seam ripped across it.

The panel on one side was on the grain, so there were three layers of fabric on the flat felled seam – I folded the fabric over twice to make the flat felled seeam.  The fabric on the other side was on the bias, so it stretched where the fabric on the grain stretched until it ripped, so I think the on the bias fabric contributed less.  There were three layers of it also.

Looking at other corners, I can see the majority of tension is along the flat felled seam on the ridge, and little tension on the edges or across the fabric.

When I fix it I’ll put more layers of fabric going up the flat felled seam.  Maybe I’ll use gros grain – that seems not to stretch very much and must be strong enough.

I don’t think making a circular reinforcement  across the body of the fabric will do much, as is typically done to reinforce tie-outs.

 

[Sam Farrington]

Jerry,
RBTR does not have a .93oz silnylon on its site, so you may be referring to silpoly. Seem to recall that you made a half-mid from silpoly with an unfinished weight of .93 oz/yd2..
Their .93 oz silpoly is called “membrane,” along with a number of other products.  If it is the older membrane with a heavier PU (polyurethane) coating on one side,  please note that the material deteriorated some months after purchase, with almost no tear strength at all. (Ultra-Strong Charmin?)
If it is the current .93 oz membrane silpoly, you may recall from a thread by Stephen Seeber that the material had a very low water resistance of around 400mm HH after simulated aging with several machine washings in cold water. Folks can argue, but 400mm HH is more in the class of fabrics treated with durable water repellent (DWR) and is breathable, and not waterproof by any standard.  However, the same listed “membrane” fabric purchased earlier by another BPL member was tested by Stephen, and the result was in the waterproof range.  It is all on Stephen’s BPL gear forum thread. So it appears to be a matter of quality control. Your posts about your half-mid go back a while, so I’m assuming you got the better stuff.

Nevertheless, a less than one oz/yd2 material, if polyester and not nylon, is not going to be very strong. If I could have gotten the material with a better HH, as some did earlier, the fabric area near the end of the seams would have been reinforced with patches of the same material, quarter circle shaped on each side of the seam, and projecting at least 6 inches on the body of the fabric.  These work great with PU coatings because bonds can be achieved that do not peel over time due to constant stretching of the tent, especially in foul weather.  But sil coatings, on nylon or polyester, do not bond as well.  An MYOG prototype canopy made with silnylon and GE sil glue per an old BPL article showed wrinkling and separation of the reinforcement patches at every corner after being pitched in the workshop for a few months.

The best approach to sil bonds I’ve found came from Roger Caffin with Permatex windshield sealant applied thinly and clamped for at least 3 days. The fabric samples were not quite as good as PU bonds on nylon; but were very difficult to peel apart. So am hoping they won’t deteriorate, wrinkle and become useless.

Once the patches are laminated on, they are sewn into the lap felled seams and should add a lot of strength, even with a light woven polyester “membrane” material that has no ripstop or grid woven in during manufacture.

I’m still experimenting with ways to find or create a super light woven tent material that will resist tears and punctures, and be reliably waterproof. The non-woven materials, like DCF, have almost no elasticity (stretch), so weather resistance and durability are questionable. It is a work in progress.

[Jerry Adams]

yeah, 0.93 membrane silpoly is what I meant to say, good deducing on your part.  And it must be the older version.  Half pyramid with a vestibule.

I’ve had it in the rain a fair amount and it seems waterproof

I’ve been reading about the weakness of silpoly, and my experience seems consistent

I sewed a patch of fabric back on that corner, and reinforced it with a strip on the ridge.  Examining the mid as pitched, it seems like most of the tension is up the ridge so adding a strip along the ridge should make a difference.

Now, I need another trip to test it : )

[Stumphges]

Jerry, could you confirm that it has a PU coating on the inner side of the fabric?

[Monte Masterson]

So Jerry are you saying that you don’t have bonded reinforcements for the tieouts? And a non ripstop 15d silpoly membrane? I’d say the results you’ve found should be expected in moderate to strong winds. The Dutchware Xenon Sil 1.1 (which actually weighs 1.24 oz) is a 20D ripstop silpoly and has a very high HH. Pretty strong stuff. I’ve found the 7D silnylon wrinkles like a wet noodle when it gets damp, at least without some kind of frame.

[Jerry Adams]

I do not have bonded tie-outs in my 0.93 silpoly

That fabric is very light and not very strong.  I am testing to see what is too weak and fails and then what increased reinforcement is required to not fail.  I philosophically oppose reinforcements that aren’t actually needed.

I have 5 corners in my half mid.  The reinforcement is just the flat felled seam that goes up the ridge.  The other 4 corners survived, only 1 corner failed, so I am close to sufficient reinforcement.  I need more than just the flat felled seam though, I need another strip that goes from the tie-out up the ridge.

Another failure I had was a tie-out on the side.  I don’t tension those hardly at all, they’re just to keep the side from flapping.  I sewed the gros-grain tie-out to the fabric with no reinforcement, just one layer of fabric.  Duhhh… it failed.  So I applied reinforcement patches but I didn’t bond them.  That seems to be sufficient.  A better way would be to just have a 1/2 inch hem on all edges.  The seam would transfer the load of one layer of fabric to two.  Then, sew the tie-out through the two layers of fabric.  I did that on some of my hems and it seems to work.

I’m trying to work in a pun about how it seems that my seams failed or something…

[Daryl and Daryl]

Jerry,

“I’m trying to work in a pun”

Sew now you are a poet?

Seams quite a jump from resident engineer.

Hope I haven’t ruined this thread by responding.

If you want me to stop responding it would be best to knot reinforce me.  It would only encourage me to continyou.

I’ve got to get a life.  This is a waist of time.

Didn’t mean to needle you.

 

 

[Jerry Adams]

ha, ha, ha,…  good ones.  I don’t have to make any more puns now, thanks.

I’d appreciate some poetry about this too : )

[Roger Caffin]

The way some of that hem ripped off reminds me of perforated toilet paper.
I find it very helpful to have strong ‘vertical’ seams and to connect the tie-outs to those, possibly with a few inches of light gros-grain tape sewn in as well. That way the load is distributed over the length.

Cheers

[Jerry Adams]

Yeah, exactly, it’s like the needle holes of a horizontal seam act as perforations.  The fabric rips along that line

And, vertical seams provide more strength.  I thought just a flat felled seam would be sufficient, but that ripped, so now I’ve added a strip of gros grain.  That should also make the ridge stiffer so it flaps around less in the wind.

[Dave @ Oware]

Circular reinforcement patch, triple roll hem, double stick fabric tape on hem and corner seam for a few inches.

[Roger Caffin]

Chuckle: there speaks (Dave) a man who has to provide a warranty on his goods!
Always good to heed such experienced advice.

Cheers

[Sam Farrington]

To answer some questions and issues raised:

There is the Gear Aid adhesive patch for silcoated fabric, 3″ by 5″, available from Amazon and others. It is not a tape, though. Do not know of an available sil adhesive tape that could work well to reinforce an entire seam of sil-coated fabric.. The sil transfer tape does not seem to be available in MYOG quantities in the USA, after many tries, and even an order confirmation, which was then withdrawn. That’s why my sil reinforcements will use Roger’s approach with the Permatex noted above.  Would welcome info about a sil tape that strongly adheres.

Stephen Seeber was kind enough to test the The Dutchware 20D ripstop silpoly for me in July, and it did not do nearly as well as the RBTR, which maintained almost 1500mm HH after simulated aging. Note that Big Agness routinely sells shelters with 1200mm HH new! Also the HH spec from Dutchware was much higher than tested. I have encountered such variations with Dutchware before.  Note these are ripstop 20D fabrics, usually marketed as 1.1 oz (unfinished), not the lighter unreinforced 15D material from RBTR Jerry is using.

RBTR markets its basic silpoly as coated with a “blend” of Silicone and PU on both sides. I understand it is primarily silicone, and thus marketed as “silpoly”, and must be sealed with sil-based sealant, but don’t know how the sil and PU are blended, and don’t expect to find out. That is one for any chemists on BPL.

Agree that more than the seam should be reinforced with patches that are larger, but of equally light material at stress points. This spreads the tension over a larger area. To do otherwise invites rips IMO. Circular and triangular patches used this way seem fairly common in the industry. However bonding is desirable, because it prevents the patch from peeling around the edges and thus maintains dispersion of tension, as is it purpose. It also works against rips around needle hole perforations.

Just adding reinforcements limited to the seam may not be worth the weight that it adds to the tent. Note that Jerry has had some rips along the edges of reinforced seams. The tension needs to be spread further around the base of the seam where the tension is greatest. Hence the circular patches. A thin patch, extending around the base or peak of the seam may be lighter than just reinforcing the seam. If the seam is highly reinforced, that may also create wrinkles on the surrounding fabric that is very light and not reinforced.

I’m big on using fabric over fixtures & tapes to save weight; a common example being pole sleeves instead of pole clips. Clips are handier though. A current thread talks about a ‘Crossbow’ tent that uses ‘trusses.’ a combination of sleeves and clips. They say this makes it easier to pitch in high winds.  Not sure I buy that, having read Roger’s posts about how all his poles go into the sleeves on the ground, and the tent is then erected in one motion.

Many have probably heard all this before. But it is always ‘Groundhog Day’ on BPL, and that is probably inevitable.  Apologies if boring.  Daryl, that is BORing, not BOORing.

[Roger Caffin]

don’t know how the sil and PU are blended, and don’t expect that to be disclosed.
Industrial chemists are sometimes accused of practicing ‘bucket chemistry’.
So I suggest a stainless steel bucket and a SS paint stirrer. Mix well.

As for reinforcing attachments, see the following for how I do it for some attachments..

These are the flaps at ground level which hold the ends of the poles. Note the blank square area at the bottom, and the cartridge is silicone adhesive and a roller. The X-Pac fabric is used to support the eyelets: silnylon is far too light for that.

The square area is coated, then put in place on the underside of the groundsheet, and the adhesive is rolled flat. I was trying to get rid of all the air bubbles, but was only partly successful. I sewed around the edge of each patch to avoid having them slowly delaminate. This is a view of the inside of the bucket groundsheet.

It is your choice whether to sew while the silicone is wet, or whether to wait till it is dry so the needle does not get very sticky. Note that you can pin the patch in place while the adhesive is wet so you can sew it exactly right. Then take the pins out and rely on the silicone sealing up the pin holes (this works very well). I have never had any sign of failure on any of these tabs, although I should add they are not under the tension experienced by a guy rope in a storm.

This photo shows how these ground flaps are used. The small eyelet holds bungee cord which provides tension along the pole sleeve, while the large eyelet takes the pole foot, currently sitting on a little finger.

Cheers

 

 

[Jerry Adams]

of course I am over analyzing this : )

the silicone caulk or tape would prevent the perforation tearing if it was between the row of stitches and the load

the circular patch may be overkill, but it doesn’t weigh a significant amount or take that much extra work.  makes sense for a commercial product, some customers will be less careful or use in very windy conditions

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