Sil poly DIY tarp, cat cut required?

[jetblackstar]

Hi Guys,

I'm hovering over the buy button on Ripstop By the Roll for some of their Sil Poly (probably the Membrane silpoly that is stupidly light)

Originally I was intending a 11' cat cut hex tarp. But that was when I was intending Sil Nylon as the material.
As I understand it sil poly doesn't have the same stretch problem as Sil Nylon and that's what the cat cuts were for.

Is it still wise to put in the cat cuts?
While this is intended for hammock camping I do occasionally bivi camp or have other uses for tarps and I'm wondering if the cat cuts give me less options for configurations.
I know I can still A frame it with walking sticks, but there are some awsome tent like pitches I've just tried with a sqaure tarp that I dont think I could do.

Or given how light the Membrane version is just stuff both the cat cuts and the hex and stick with a rectangular tarp?

Any advice would be appreciated.
I'm in the UK and its expensive to ship and pay import duty so this is a special post christmas treat, and I dont want to cut off bits I needed lol.

[Monkeyboy42]

I built my silpoly tarp without cat cuts, and I don't miss them. Many others seem to have had similar experiences. Mine pitches pretty darn tight. That said I haven't had it exposed in a wind storm to really judge...

You can always build without the cat cuts, and then if you feel you need them you can add them after the fact. Which ever way you go I've found silpoly superior to silnylon for tarps. Minimal stretch, just as waterproof, and not as slippery to work with. In fact it's significantly easier to work with.

[jetblackstar]

That's a good point about being able to retrofit the cast cuts.
Not adding them does make the design really simple.

Sounds great material for me, its my first diy tarp. Thought I've made a few things with the sewing machine so far.
Just need to settle on the best camouflaged colour, dark olive is winning ATM lol

[FJRpilot]

SilPoly is great stuff! I, like Monkeyboy42, omitted the cat cuts on my 11 footer and I'm very happy with how it pitches. I do use an internal pole mode because it's my winter tarp w/doors and I like having lots of room. The interior poles help increase the tension and I think it helps the tarp overall in both the wind and snow. I would not hesitate to leave them off the next one I make and as MB also mentioned, you can always add them later if you want.

[jetblackstar]

Thanks FJR I'm started to get exited about this tarp
As so glad I noticed silpoly just before I bought silnylon

[xxl_hanger]

I add them at once. It is simple math why they are helpful. I will have also a moderate cat cut on the first line. Why? Because your tarp ridgeline is never straight or only almost straight if u use a very high tension.

With cat cuts it is much easier to pitch your tarp tight. There is nothing wrong if you use them with a silpoly tarp too. Sewing is only a bit more work and without cat cuts the work is much easier.

[Caminante]

I did a silpoly tarp with catcuts except for the ridgeline, and I wouldn't do them again if I made another one. It was my first major sewing project and while putting in cat cuts wasn't a huge deal by using a template, I don't think it added anything functional given the low stretch of silpoly. The ridgeline, as you can see, is plenty taut without a cat cut and naturally assumes that shape, anyway.

IMG_20150809_092422-01.jpg

[Snowball]

IMO you don't need cat cuts in SilPoly.

[xxl_hanger]

You guys should messure the tension on any square inch of your tarp. I guess with cat cuts the tension is much more homogeneously distributed.

[jetblackstar]

Thanks guys. I'll start without the cat cuts. I can add them later if it doesn't pitch tight enough.

Xxl_hanger, I'm sure your right that it will be tighter with the cat cuts. Sounds like without the stretch of sil-nylon itisnt quite so important. But since sewing the cat cuts back in isn't an option I'll try without and I can change my mind.

I'll be sure to report back here regardless.

I presume from all the hex tarp responses my question of leaving it a square tarp was a silly one

Thanks everybody.