How To Make Perfect Catcuts On A Tarp

[Lost_Biker]

Just find yourself an outside wall of a house, or maybe a walmart. Should be plenty long enough.

Hmmm - I wonder what wally world would think I was doing?

Police: Sir? What do you think your doing?

Me: Sorry officer! Just measuring cat curves as an experiment. Be done in a few minutes!

Police: Cat curves?

Me: Yeah! Could you hold the end of this string for me? That's it - a little higher. No, a little lower now. That's it! Hold still right there!

[GrizzlyAdams]

After making a few tarps using this method, I find the depth of the curve to be important for making a taut pitch. For those starting a tarp for the first time, its quite intimidating working with catcuts and I admit it's not perfect, but it will get you in the ballpark.

So, I apologize for listing the title as "perfect curves". One thing that the pipe method does do is make the catcuts on both sides more consistent, although they're not true curves. My plastic pipe at 10' long can be bent to make curves with a depth of 4 or more feet - it's what I use to make the dory boat curve on my hammock socks. Me and math don't get along that well anymore, , hence the plastic water pipe to help me along!

Cutting out cardboard templates that have a true parabolic curve would be a better solution and be more accurate.

hey, no apologies needed. You'd got a good idea. It is "truly" a continuous curve, symmetric about a single global extrema, with shallow draft. It works. Once upon a time in another thread I climbed up on a soapbox and railed against any significant difference between a cat curve, a parabolic curve, or a bent pole curve at the depths and purposes we use for tarps and hammocks. Point was I didn't (and don't) think it makes any practical difference.

True confession, I've done some of these curves freehand, when I'm in a hurry. That shows just how important I really think the mathematical details matter. (but admittedly I free-handed only half the curve and doubled that over, to ensure symmetry).

[Lost_Biker]

Thanks Grizz! I really like the convenience of the 1/2" pvc. I just finished the other panel and everything came out the same on both panels - I put one panel on top of the other and the curves match.

When I get some supplies I ordered from Scott@diygearsupply, I'll finish and post pics.

[Whiskeyjack]

You never know Lost, you could make another convert.
Can't wait to see the final pics.

[sargevining]

I love the thread and plan on using this when I make my tarp but I gotta say there's a problem with the title, but its mostly me.

I look at the title in the New Posts List and wonder why anybody would want a perfect cactus on their tarp.

[Lost_Biker]

You never know Lost, you could make another convert.
Can't wait to see the final pics.

All I'm waiting for are some supplies to make the ridgeline and tie outs. I placed an order with Scott, but I guess he's up to his neck in alligators right now. The hemming on both sheets is done - took a total of 1 1/2 hours to do a 1/4" edge. While slick at the beginning, the syl fed great thru my Singer 201 after I cranked on the foot pressure a bit. Had no problems with the curves at all.

Pictures will be posted as soon as I get my package. I'm going to try something different for the ridge - not gonna say what yet - in case it doesn't work.

I did go against what I usually do first which is sew the ridge first, but after zipping thru most of the work so fast, I'll put the panels together last.

I love the thread and plan on using this when I make my tarp but I gotta say there's a problem with the title, but its mostly me.

I look at the title in the New Posts List and wonder why anybody would want a perfect cactus on their tarp.

You know you made me stop and go check the title to make sure it didn't say "cactus" don't you?

I have to say that if I had all the materials on hand, that I could finish the tarp from start to end in one day. The syl I got from Quest Outfitters is listed as seconds, but I can't find anything wrong with it - looks as good as 1st's.

Don't let sewing the curves scare you. I just folded the material 1/4" and sewed it down. It went really fast and smooth - I used the dining room table to sew it and the tables not that big. Just start on the end and keep folding.

I should say that I will not be using grossgrain on the edges.

[Lost_Biker]

OK! FINALLY finished!

I don't have a total weight yet as I was up till the wee hours sewing, er, injecting thread to finish it this A.M.

The cat curves came out perfect. I made the ridgeline differently - instead of a flat felled seam, I used 1" grosgrain folded over on the seam very much like the warbonnet method. Super strong and I can really tighten it without fear of pulling something apart. I also used the same 1" grosgrain for the pull outs instead of using heavy pack cloth.


I used 3/4" welded rings on the ends of the ridgeline. 1" triangles for the ends and 1/2" beastee dee rings for the 4 inner pull outs.

The ridge is 10' from ring to ring, but the door ends come out another 5.5" - the total length is 11' 11" end to end from the door ends. All edges are 1/4" seams made with my 1/4" multi-purpose foot from Sew Classic.

The total width is 10.8'. I chose grey as in the winter I wanted more light than a dark color could provide. It also brightens up the inside at night using a candle or head lamp.


I'm going to try to have the panel pulls done hopefully today or tonight and will post that tomorrow.

[Hiknhanger]

That looks really good, L B! I like that ridgeline setup with the grosgrain. I haven't seen one like that before. If I got brave enough and had the time to DIY a tarp, I'd do that for sure. Great job. Those cat cuts look great.

[Lost_Biker]

That looks really good, L B! I like that ridgeline setup with the grosgrain. I haven't seen one like that before. If I got brave enough and had the time to DIY a tarp, I'd do that for sure. Great job. Those cat cuts look great.

Thank you, Hikn!

Warbonnet uses a better method that is similar, but I just put it together with the size grosgrain I had on hand. It's absurdly strong and doesn't stretch - that I've seen yet. I'm going to let it hang in the strong wind (20mph gusts) we're having right now and see.

Using the grosgrain adds strength, but weighs more. Here's some better pics.

Weight came to 20.49oz with all lines and mini carabiners.

Also, I need to say that this is a "short" winter tarp. It's not the 132+ ridgeline that winter tarps usually have. I cut down the length and increased the width for my use only. So size your tarp correctly!

[Whiskeyjack]

Great looking tarp!
I like that ridgeline idea. Looks super strong.