Tarp Tie-Out Questions

[AG]

Oh and assuming you’re running your line from tree to tree under the tarp, you secure/tension tarp to ridge line with prusiks. Rule of thumb is the prusik cord diameter should be smaller than whatever it’s looped on to. Otherwise the frictioning doesn’t work as well.

[Hoosier T]

Haven’t used that line. But a trucker’s hitch will get you the best tension on a ridge line, because it’s basically a pulley. (And you get to tie my favorite knot, the alpine butterfly!) then I don’t see why you couldn’t secure the line with your blakes hitch or any similar guyline knot (or just a half hitch).

 

I actually just learned how to tie an Alpine Butterfly this week as I’m trying learn as many knots as I can before I use a tarp. However, forgive my ignorance, but how does the trucker’s hitch play into it? Does it get tied to the standing end of the line after I wrap the tree?

[Hoosier T]

Oh and assuming you’re running your line from tree to tree under the tarp, you secure/tension tarp to ridge line with prusiks. Rule of thumb is the prusik cord diameter should be smaller than whatever it’s looped on too. Otherwise the frictioning doesn’t work as well.

I was not planning on running the line tree to tree but rather using the tie outs on each end of the ridge-line. That not a good idea?

 

 

[Hoosier T]

I intended to use an overhand to create a loop on the tree end, then girth hitch the line to the tree, back around, through the tie out on the tarp, then a Blake’s hitch in between for tensioning. Is that logic flawed? I’m brand new to this so no feelings will be hurt in this exercise. :)

[AG]

Tie an alpine butterfly between tarp and tree. Run line around tree and then back through butterfly. Then haul backward toward tree to tension. Tie off loose end (to the section you just put through the butterfly).

[Hoosier T]

Ah, so the trucker gets used as the tie off after looping through the butterfly and tensioning. Nice…

[AG]

Yes there’s no single right way. :) as long as you can get the pitch you want. That’s the beauty of tarps.

Re tree-to-tree. Someone else correct me but i believe this is a nylon vs cuben question. Nylon tarps need tree-to-tree under support. But cuben is strong enough to just connect from tie out points. Although running a cord under is always gonna be stronger and put less tension on your fabric – cuben or otherwise.

[Hoosier T]

See, when I practiced the butterfly, I came around the tree, through the butterfly loop, then tied the standing end off using a blake’s hitch. This allowed me to adjust tension after the line was tied off and adjusting the hitch actually benefited from the mechanical advantage. it seemed to work really well.

[AG]

Yup that’s exactly what I do.

[IVO K]

Someone else correct me but i believe this is a nylon vs cuben question. Nylon tarps need tree-to-tree under support.

@ AG:

If by “nylon tarps” you mean those made out of silnylon or silnylon-poliester, then you are incorrect. They do not “require tree to tree under support” as you formulated it.

If you use “under support” with those, you risk their premature failure as the friction especially when windy would abrade them extensively. Besides, such “under support” may make tensioning the tarp’s ridgeline very difficult or impossible.

If you instead meant tarps made out of other plastic materials – then you might be correct, as I don’t have any experience with such exotic creatures.

[Hoosier T]

I guess this is where I come in. This will be a tarp made from RSBTR’s Membrane Silpoly and the reinforcements will be circles made with their HyperD 300. So…does that mean I should not run a full ridgeline? If not, will the tarp support being tied to two trees simply by way of the ridgeline tie-outs? If I have to use trekking poles I can but it would certainly be nice to be able to throw it up on trees when possible. I see this being done with other tarps, such as hammock tarps. So now I’m confused…

[Hoosier T]

So, after further searching, I have found that skipping the full length ridge line and just tying to each ridge line tie out seems to be acceptable and reliable with the exception being snowy conditions and in those scenarios you would run the full length ridge line ABOVE the tarp. Can anyone please confirm my findings before I wake up to a tarp on my face. :)

[James Marco]

Hoosier, I don’t think I would do that with poly, ie the ridge line above. Poly is simply not strong enough compared with Nylon.  (https://www.curbellplastics.com/Research-Solutions/Plastic-Properties) Roughly, it is about half as strong without coatings. With coatings, it might be about 2/3 the strength of nylon.

For nylon tarps, I use a simple doubled hem. Fold once, fold, again sew, then fold again and sew twice to flatten. For ridge lines, I usually use a doubled flat seam so there is 6 layers of fabric. So, placing some 3/4″ nylon webbing on a 10′ tarp means I can tie this off to a couple trees, even in a rather heavy wind (up to about 40mph.)

The heavy seaming means I have a place to anchor webbing loops. I do not worry much about the overall strength of the panel, it will generally be stronger than the seams due to the sewing. Even soaked it is about 20% stronger than poly, anyway.

The ridge with poly done the same way only have the same strength as ~half the layers of nylon on the seams (assuming an A-frame pitch.) I would do an extra roll on the center seam simply to add additional strength and the same for the hems. This should provide the extra cushion for a heavy gust and still maintain itself. Skip the center rope. It only provides an avenue for abrasion where the poly cloth is again weaker than nylon. Unless you plan on using a 3/8″ ridge line, of course, but that is way overkill. Otherwise it sort of acts like an edge for tearing…similar to tearing paper on a sharp edge.

Adding a center loop is only asking for trouble. This will add stiffness to the center (assuming you have a center rope, again.) Generally, you will find it hard to maintain even tension between three points (two points define a straight line.) So it will add stress on the middle, or, do nothing. (assuming 3mm, spectra lines.) In a gust it would help with deformation. But if the tarp was tensioned properly while you set it up, it will apply a disproportionate amount of stress on the tarp. Kind of like tying off a rope and pulling on the center.

 

 

[Hoosier T]

So for a “double flat seam”, are you just doing a flat felled seam then folding the finished seam over again and sewing once more?

[Hoosier T]

I’m not going to overthink this. using a traditional flat felled seam on the ridgeline means five layers. Then when I roll hem the perimeter including the rolled in reinforcement patches of 300 denier nylon, I will be left with 11 layers to attach my ridgeline tie outs, which includes three layers of the 300 d. I really can’t imaging having issues there. The perimeter tie outs will have three layers of poly and three layers of 300 d nylon to sew through so should there really be any concern here? I have seen threads where people have built 8 x 10 tarps with RSBTR’s Membrane Silpoly (.93 oz/ sq yd) and didn’t even use reinforcements and had no issues. My tarp will be considered way overbuilt by some people’s standards I think.

[Matthew / BPL]

Another option might be reinforcing the ridgeline with grosgrain like on a Warbonnet Superfly tarp.

FWIW, the hammock crowd does not usually run ridgelines underneath their tarps. Many do two separate lines and some do a continuous ridgelines, almost always over the tarp. My understanding is running the CRL over the tarp allows the natural curve of the ridgeline to come into tension, particularly with a cat-cut RL. I think it’s more typical to run a line under the tarp with a flat tarp in an A frame or modified shed pitch.

This thread may not be of interest here because of the reliance on hardware and zing-it but it’s a fantastic system that myself and many others have used for many, many nights.

[Hoosier T]

Yea mine will be a flat tarp and frequently pitched in an A frame. I likely will use Zing it for the ridgeline if tying off to trees. Otherwise, when using trekking poles, I will be using Lawson’s Glowire. That thread is helful but I feel I can forego all the hardware with the knowledge of knots I’m working to expand.

[Hoosier T]

So going back to an early post saying not to tie to trees WITHOUT a continuous ridgeline. I would like to get clarification here. Saying that would imply that tying to trees would impose greater force on the ridgeline tie outs as compared to using trekking poles. Scientifically, it would seem to me that the force required to get a ridgeline taught would NOT depend on the method used to secure each end. Would that not be true? If it is then it seems that I need to stop worrying about this and just tie that bad boy to a couple trees (NO CRL) and move on with my life.

[James Marco]

“So for a “double flat seam”, are you just doing a flat felled seam then folding the finished seam over again and sewing once more?”

There are a LOT of different ways to make flat seams. Think of them as two hands with the fingers clasped together, a total of four layers of fabric. Rolling once again gives 6 layers of fabric. Enough to rival 3mm line in tinsel strength, even wet. So, I don’t bother with a ridge line, under or over.

Yes, you would need 11 layers of poly cloth for the same strength.

Unfortunately, using dissimilar materials will likely not improve the strength much. The nylon has more stretch. So, all the large majority of the stress will be on the poly portion of the seam. You could end up splitting the polly, but still have the nylon intact in 60-70mph winds. But this is REALLY extreme. The same applies to poly webbing attached to poly cloth. I am sure the web will have more give, being a coarser weave. But this is not something to worry about. Normally the fabric would rip out along the seams (at it’s weakest point) first.

Really, strong loops are needed only to insure that they are not the weakest point on the tarp. When setting up, pull till the tarp is taught, not as tight as possible. Trees move. A typical 8″ tree will flex 1/4″ to 1/2″ at 4′ above the root. The stretch in the tarp is usually enough to compensate for this. I have a wood pile between a couple trees. After a spring wind storm with ~50-60mph gusts, I sometimes have to pick up a pile of firewood when it gets knocked down. The flexing causes all sorts of problems.  Ground stages will give a bit. So, it isn’t a problem when one end is on a treking pole/stake. And the guy line angle also allows some movement.

 

 

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