BlackCat Directions

[blackbishop351]

Since there's been some tarp talk around lately, I thought I'd go ahead and post my directions for making my BlackCat tarp. Here's the link:

http://teamgunnparker.com/blackcat_tarp/Black_Cat_Tarp.htm (http://www.jhatkhat.com/Khat/camping/bcdir/)

I held off posting these for a couple of reasons. First and foremost, I wanted to talk things over with Brian of OES (designer/maker of the MacCat) beforehand. He was great to talk to and VERY supportive of having these publicly available. He's also going to send me his comments on different sections at some point so I can add them - that way people can see how he does things differently in places and have more options.

I'm also not completely done editing these, but I think they're useable at this point. Note: There seems to be a problem with some images loading in IE6 (and maybe earlier versions). Maybe someone more experienced with HTML can help me work out that bug (hint hint Jeff or Troll :p )? IE7 and Firefox seem to work fine though.

If you use my directions and make a tarp, be sure to let me know how it went for you. I'd also love to have comments and suggestions on things you like or things I should think about changing - formatting, content, whatever.

Enjoy!

[headchange4u]

Site looks great BB. Excellent work. Every thing loaded fine for me (I use Firefox).

I REALLY like the section on setting the tarp up on the ground. That's cool.

[blackbishop351]

Site looks great BB. Excellent work. Every thing loaded fine for me (I use Firefox).

I REALLY like the section on setting the tarp up on the ground. That's cool.

Thanks, man. I added that ground pitch section in response to a lot of buzz I read on WB a while back, talking about Brian's tarps and how they were too limited to hammock use.

[lvleph]

Okay, now I am more convinced that one of these tarps are usable on the ground. However, I want a poncho tarp, so I am not sure if this is adaptable to that. What are your opinions on this?

[NCPatrick]

Under materials, you forgot to include large textbooks about Math or Physics, used to weigh down the sil material while you work on it.

I suppose any other kind of weights or books would work, but it does seem that the weighty subjects inside your textbooks work best.

[blackbishop351]

Okay, now I am more convinced that one of these tarps are usable on the ground. However, I want a poncho tarp, so I am not sure if this is adaptable to that. What are your opinions on this?

IMO, a cover small enough to use as a poncho wouldn't provide enough coverage for a hammock. Then again, I'm a weenie about getting my shelter wet.

I do understand your desire for multi-purpose kit items though. My solution is (or will be very soon) a Packa-like poncho made out of Tyvek. It's a bit heavier than the sil version, but also a lot more durable. It could be used as a ground sheet if necessary, for sleeping (let's hope not) or for keeping a pack off the ground. It could also be strung up as additional coverage in really bad weather. The one I'm getting can be found here if you're interested:

http://www.goodlingoutdoor.com/Poncho.html

[blackbishop351]

Under materials, you forgot to include large textbooks about Math or Physics, used to weigh down the sil material while you work on it.

I suppose any other kind of weights or books would work, but it does seem that the weighty subjects inside your textbooks work best.

Over the years I've realized I shouldn't automatically assume that everyone has a Giancoli lying around the house....although they should! :p

[lvleph]

Over the years I've realized I shouldn't automatically assume that everyone has a Giancoli lying around the house....although they should! :p

I actually do. But hey I have a degree in Mathematics and I like to mess around with Physics. In fact, I have Quantum Theory, Bohm sitting next to me along with Introduction to the Theory of Relativity, Bergmann.

[blackbishop351]

I actually do. But hey I have a degree in Mathematics and I like to mess around with Physics. In fact, I have Quantum Theory, Bohm sitting next to me along with Introduction to the Theory of Relativity, Bergmann.

Sweet! Do you have the Rudin trio as well? And we can't forget Woods' Advanced Calculus... :D

[Coffee]

I'll see your guys' Calculas book and rasie you a linear systems design and Random Processes (Random Matrix stuff).

[blackbishop351]

I'll see your guys' Calculas book and rasie you a linear systems design and Random Processes (Random Matrix stuff).

You should talk to my friend Jarrett on that one - he spent last summer doing a lot of random matrices stuff, along with singular value decompositions geared toward image analysis.

[Coffee]

You should talk to my friend Jarrett on that one - he spent last summer doing a lot of random matrices stuff, along with singular value decompositions geared toward image analysis.

And we used that to model our hammock setups and preduct their load rating and life span.;)

[blackbishop351]

And we used that to model our hammock setups and preduct their load rating and life span.;)

Well everybody wants gear pictures...have to make sure they're good quality! :D

[stoikurt]

And we used that to model our hammock setups and preduct their load rating and life span.;)

I was wondering how you were going to bring that back to hammocks!:D

[blackbishop351]

BlackBishop - can I get you to change the background. Using a dark background with a dark font makes it very hard to read the font. These old eyes just don't like squinting anymore. I tried turning the lights off and closing the drapes on the windows to get the screen "lighter", i.e., more contrast. No good. Half the words just kind of fade into the background.

If you look at the forum, it uses a light background and dark, black font. Really easy on the eyes.

Maybe it's just because I'm used to reading black font on white paper.

I find I'm running into this more and more on some web sites. I've gotten to the point that when I run across a web site that I cannot read easily, I just skip it. It's just not worth my time anymore to squint and squint and attempt to read something and get a headache doing so. I actually found one commercial web site where the designer used a pure black background and a dark green font. Never did understand how anyone was expected to purchase their products - couldn't find out what they were.

Is it the fashion now - kind of a rebellion against that old fashion type on paper and now that we have the computer, we can do all these fancy things??

Or is it a youth thing - like the phone rings I've read about - I haven't heard them myself :D, but I read where the young kids had found a phone ring for their cell phones that old ears couldn't hear. They could get calls in all kinds of places where their parents, or teachers didn't know they getting them?

Keep us old folks in the dark literally, if we cannot read it, we don't know what you're doing .. :D

Thanks for the suggestion - the background color in the text boxes shows up as a pretty light tan on my screen, but I've heard several people say it looks different on theirs. I'll try and lighten it up more and see if that helps!

[blackbishop351]

BlackBishop - does anybody still use Morse and Feshbach or Courant and Hilbert. I don't suppose Synge's 2 volumes on Relativity, Special and General, is still used any more. Moller was never really used much, but was excellent.

Too many decades back even if the subject matter is still relevant and the same. :D

It seems that Physics books change a lot more frequently than math texts - I'm not sure why. Griffiths' series (E&M, Quantum, and Particle) has been the primary source for my upper-level undergrad classes. We used Schroeder for Thermal. Jackson for graduate E&M is by the far the most popular, and Mertzbacher is up there for grad Quantum.

[FanaticFringer]

Yea the text is very dark and hard to read on mine as well. Is that my BlackCat you got in that picture?:cool:

[Just Jeff]

I'll see your geekspeak and raise you one "back on topic." :D

BB, I'll have a look at your code when I get back home...I'm on the road at the moment and limited to 30 min on the library computer!

[blackbishop351]

Yea the text is very dark and hard to read on mine as well. Is that my BlackCat you got in that picture?:cool:

I'll get on the background color for sure then. And yes, that's your Mark II in my yard :p

[blackbishop351]

I'll have a look at your code when I get back home...I'm on the road at the moment and limited to 30 min on the library computer!

Thanks, and no hurry!

[NCPatrick]

Here's the color for the tan background here: #EED8B0, as in
<body bgcolor="#EED8B0">

HTH.

[blackbishop351]

Hmm...that's the BG color for HERE...doesn't look right on my page. I'm trying to find something subdued, maybe with green in it, that'll be light enough to read easily.

[Bird Dog]

:D
I'll see your guys' Calculas book and rasie you a linear systems design and Random Processes (Random Matrix stuff).

I see your books and raise my maglight! :D (Thats an inside joke that those at the Hammock Campout would understand).

Anywhooo, good looking site Keith. If my sewing instructor would continue the lessons, I may try to make one, some day for my kid. BD

[slowhike]

i went over to BB's house last week end & i helped him w/ a work table & he helped me w/ a pattern for a cat cut tarp.
he started talkin all that math stuff to me & then he smiled & stopped... when he saw my eyes begin to glaze over:o
now i can figure out how to make a few things work, but i'm more likely to put two tarp parts together & see how they actually fit... instead of trying to figure it out mathematically:rolleyes:

[slowhike]

:D

I see your books and raise my maglight! :D (Thats an inside joke that those at the Hammock Campout would understand).

Anywhooo, good looking site Keith. If my sewing instructor would continue the lessons, I may try to make one, some day for my kid. BD

don't you mean... raise a taze ???:p

[Coffee]

i went over to BB's house last week end & i helped him w/ a work table & he helped me w/ a pattern for a cat cut tarp.
he started talkin all that math stuff to me & then he smiled & stopped... when he saw my eyes begin to glaze over:o
now i can figure out how to make a few things work, but i'm more likely to put two tarp parts together & see how they actually fit... instead of trying to figure it out mathematically:rolleyes:

After I made mine, I think their is some bit of error that you can account for. It is just a matter of a little extra cutting and eye balling. The engineer in me tries to get everything exact, then the DIY'er in me makes whatever comes out work.

[slowhike]

After I made mine, I think their is some bit of error that you can account for. It is just a matter of a little extra cutting and eye balling. The engineer in me tries to get everything exact, then the DIY'er in me makes whatever comes out work.

yeah, after i get all those little marks made (about a million:eek: ) i'll let my artistic eye take over (or is that autistic:confused: ) & make that graceful, sweeping, curve.

[Coffee]

I think on my next tarp I am going to use some super heavy supplex I have. That should lay flat and make sure both sides come out the same. I think that is the biggest part in getting a good looking tarp. But then again, I only made 1.

[slowhike]

BB helped me make a tarp pattern on some kinda thick, cotton, broad cloth from the $1.00 bin.
i would have liked to had something thicker, but that was the best i could find there.
ed speer showed me his patterns & they are on a heavy fabric that has a pattern on one side & another cloth backing on the other side. maybe it's something like you would use for big, heavy curtains or something.
he can fold them up & through them on a shelf, but when he unfolds them on the work table, they are labeled & have measurements & stuff that's helpful.
but the main thing is that the heavy fabric does little or no stretching so it gives a reliable pattern to trace.
and they are easy to handle & store.

[Just Jeff]

Great looking page, Keith. Very clear and laid out nicely. When I looked at Step 2 I had to scoll right/left to see the whole page...might be worth reformatting that so it displays like the other pages.

Hrm...I think it would also benefit from one more blurb under the menu links...


<a href="http://www.hammockforums.net/forum/showthread.php?t=654">Discuss this project</a> at HammockForums.net.

:D :D :D

[blackbishop351]

Great looking page, Keith. Very clear and laid out nicely. When I looked at Step 2 I had to scoll right/left to see the whole page...might be worth reformatting that so it displays like the other pages.

Hrm...I think it would also benefit from one more blurb under the menu links...



:D :D :D

Yeah it looks like I'm still having some formatting issues. I'm trying to find a good background color to fix the darkness problem people have been reporting. I'll see if I can figure out why that page loads differently, too.

Thanks for the compliment! Means a lot coming from a guy with a page like yours!

[nickelsanddimes]

Wow, thats nice. After reading your site I'm almost embarassed by how I made my cat tarp. Instead of taking the cuts off the edges I took one big cut off at the ridgeline and carefully matched up the two panels then just cut off the outer points( going to the ground )of the diamond.

[funbun]

Okay, I'm reading the directions and I'm confused.


Rotate the ruler, keeping the "zero end" at your chosen corner, so that it crosses the opposite edge NEAR length "a".

What? Got any pictures? What opposite edge? The edge parallel to the ridgeline or perpendicular? I'm just confused on the orientation.

[blackbishop351]

Okay, I'm reading the directions and I'm confused.



What? Got any pictures? What opposite edge? The edge parallel to the ridgeline or perpendicular? I'm just confused on the orientation.

Sorry about that....my mathematical brain sometimes lets me forget that most people aren't privy to the mathematically precise definitions of terms. Here, opposite means "not adjacent", i.e. the other long edge, parallel to the ridgeline.

[lvleph]

opposite edge-----O--------------
| / |
| / |
|/ |
0-end--------------------
There is an image in my Excel Calculator that will explain it pretty well.

BB shouldn't it say when it crosses length b? Since we would be measuring from the edge of the fabric.

[blackbishop351]

opposite edge--------------------
| |
| |
| |
0-end--------------------



There's your new trail name - Ascii! :p

[lvleph]

lol, but we are not on the trail.

[blackbishop351]

lol, but we are not on the trail.

I'll just have to remember the name until we can get some hiking in then :p

[funbun]

Patterns. Do you make your patter the same lendth and width as the tarp itself or do you just make it long enough to make the cat cuts?

In other words, 12 feet x 74 5/8 x 74 5/8x 74 5/8? Or is it simply one piece measured 78 5/8 inches x 5 inches?

[stoikurt]

Just make a pattern of the cat cut curves. That's really all you need.

[funbun]

Just make a pattern of the cat cut curves. That's really all you need.

Whew, good. That would make life easier :o

[blackbishop351]

Whew, good. That would make life easier :o

Yeah, definitely just make a pattern for the curves. If you were mass-producing tarps having a full pattern would be an advantage, but for just one or even a few, the curve pattern alone is plenty.

[Coffee]

I made one only of the cat curves. I think if I do it again I am going to make a full patern. To me that is easier to get 2 exactly matching pieces.

[lvleph]

I also only made one for the curves, out of newspaper.

[Redtail]

It would be cool if someone could make a pattern that could be printed out, them trimmed and taped together (just the curves). Please? I didn't have enough confidence in my curve cutting skills to to take the time to plot out all the calculated measurements only to have it turn out bad anyway. I ended up just hanging a string and tracing it on paper but it didn't turn out very well.

[Coffee]

It isn't that hard to measure out. Draw a straight line. Then lay a tape measure out the length of the straight line. Then measure in with a ruler every 1/8 of an inch and put a mark where the cat measurement was. Then draw a line connecting all of the dots.

I fudged the line a little to make a good curve. I think there is a little more fudge room in this than you think. Mine came out pretty good with a little bit of fudging on each step.

[NCPatrick]

Draw a straight line. Then lay a tape measure out the length of the straight line. Then measure in with a ruler every 1/8 of an inch and put a mark where the cat measurement was. Then draw a line connecting all of the dots.

Not quite following you there HE. What do you mean, "where the cat measurement was"? Can you describe the measuring process again?

[Coffee]

Sure. The cat measurements BB gave were labeled every 1/8 of an inch. So I measured out every 1/8 of an inch, than in to whatever the distance given for that cat measurement was. I drew a dot at that point. When I was done I had something resembling an arch with all of the dots. I connected the dots but in a way that gave an arc shape.

[NCPatrick]

Ok. I understand your explanation better now.

Thanks.

[lvleph]

The new macro that I made and that is up on BB's site now has the measurement every 1" with the cat rounded to an 1/8". This makes drawing the curve even easier. I was toying with the idea of having the ability for the macro to print out the pattern, but I couldn't figure out how I would do it. I am still thinking about it. It will take a bit of time, since I don't have windows to make the excel macro. I was also thinking about doing the same thing with a Java Script. This way one can run it from their browser.

[NCPatrick]

Would you mind making a macro that will go ahead and cut the sil while you're at it?

[lvleph]

Now wouldn't that be nice. I could but then it would be expensive. Wouldn't be worth it.

[lvleph]

Yes please - do it in Java, then us few that don't have to suffer with Windows :D can still use the generator. Also, you may want to allow the user to then specify the spacing.
I don't even have windows. lol

[blackbishop351]

Also, you may want to allow the user to then specify the spacing.

I understand wanting the generator to be customizable, but in that case why not just write your own code? I wrote my own to begin with, and I found that 1" horizontal increments made the layout much easier - finding even inches on a ruler is much easier than, say, eighths.

[lvleph]

I did write it to allow the user to use their own spacing, but it didn't end up on the site. You got that right BB?

[blackbishop351]

I did write it to allow the user to use their own spacing, but it didn't end up on the site. You got that right BB?

That must be the one I downloaded but haven't had a chance to look at and post yet :p I'll get to it - last final exam tomorrow.

[lvleph]

Ah, yeah work on those finals. I am going to start back in school in the fall and will have to deal with that stuff again. I guess 7 yrs of college is just not enough for me.

[funbun]

The new macro that I made and that is up on BB's site now has the measurement every 1" with the cat rounded to an 1/8". This makes drawing the curve even easier.

Cool, this does seems easier.

[Kiyu]

That must be the one I downloaded but haven't had a chance to look at and post yet :p I'll get to it - last final exam tomorrow.

End to end your BlackCat tarp is 12 ft. What is the spacing between the two tie outs?

Thanks
Kiyu

[blackbishop351]

End to end your BlackCat tarp is 12 ft. What is the spacing between the two tie outs?

Thanks
Kiyu

12' is between the tie-outs. Roughly, anyway - that's before sewing.

[Jazilla]

But after sewing and adding webbing might bring it back to 12 or maybe an inch or two more. The beauty about this design is it is very versatile. I made mine 144" by 120"because my material is only 60" wide.

[Suzyqhoo]

Hi!

Has everyone that has made their own tarp used the diluted silicone for sealing the main seam or have you found a commercial product that works just as well?

Thanks!

Suz

[slowhike]

Hi!

Has everyone that has made their own tarp used the diluted silicone for sealing the main seam or have you found a commercial product that works just as well?

Thanks!

Suz

as far as i know, the most popular method is the 100% silicon diluted w/ white gas or mineral spirits.
that solution blends the newly applied silicon w/ the silicon on the silnylon, & fills all the needle holes & seems.
i use a disposable foam paint brush to apply it, working it back & forth to force it into every seam & hole. works great.

[Suzyqhoo]

Thank you Slowhike! :)

This is exactly the information I was looking for!

My Mother (who has been sewing her entire life) & I got started on my tarp last night and I am beyond excited about it! I've been wanting to make one for months now!

Happy Hanging!

Suz :D

[stoikurt]

I made one and used the diluted silicon method with very good results. Use a cheap foam brush or one you don't mind throwing away when you are finished.

[Peter_pan]

Hi!

Has everyone that has made their own tarp used the diluted silicone for sealing the main seam or have you found a commercial product that works just as well?

Thanks!

Suz

Silnet work great.... get it at any gear outfitters....

Pan

[slowhike]

Silnet work great.... get it at any gear outfitters....

Pan

i had forgotten about the "sealnet". the "seamgrip" that's been around a lot longer & is used on non-silnylon type tents, tarps, etc, wont do the job on silnylon though.

just curious... i'm guessing the DIY silicon mix would be cheaper for those willing to go to a little extra trouble???

and i'm also guessing that the silnet comes thin enough to brush into the holes as it comes from the tube???

[Peter_pan]

i had forgotten about the "sealnet". the "seamgrip" that's been around a lot longer & is used on non-silnylon type tents, tarps, etc, wont do the job on silnylon though.

just curious... i'm guessing the DIY silicon mix would be cheaper for those willing to go to a little extra trouble???

and i'm also guessing that the silnet comes thin enough to brush into the holes as it comes from the tube???


Slowhike, et al,

McNett brand Seam Grip is great for regular nylon..... It will not work on silnyl.


McNett brand SILNET is the best commercial seam sealler for Silnyl IMHO....It generally runs between $6.50 and $7.99....It normally has a small brush with it.... Goes on easy.... you can also spread it with the finger and wipe off the finger with a paper towel.... Given the price of a tube of silicon and the price of a pint of mineral spirits (unless you already have this stuff in the garage, etc) it is way less costly and a whole lot less messy than the DIY approach.... Save the left over tube for another day... or ....pack the half tube in your field repair kit... All in all a great approach to silnyl seam sealing for tarps and small tents.....

DIY is probable less cost if you are talking of sealing a Wally World 10 x 18 three roomer or doing a group of tents at one time.

But since JRB carries it, http://216.83.168.206/index_files/SilNet.htm standard disclosure, "I may be biased".... but anyone can check the facts and decide for themselves.

Pan

[Suzyqhoo]

Thank you for all your replies!

We finished my tarp tonight! My mother is a whiz!

Now all that is left to do is seal it and find somewhere to go try it out! Wahoooo!

I am going to try to find some of the commercial sealer. I think I have some silicone in the garage, but I have no idea how old it is and know I do not have any mineral spirits.

Ok...must-sign-off...work-tomorrow!!!

Thanks again!

Suzy

[Suzyqhoo]

Thank you Blackbishop351 for posting the directions for making the Blackcat!!!

And to everyone here on Hammock Forums for all the hints and tips I have been reading since deciding to try hammocking (and making a tarp)!

Happy Hanging!

Suzy :D

[FanaticFringer]

Thank you Blackbishop351 for posting the directions for making the Blackcat!!!

And to everyone here on Hammock Forums for all the hints and tips I have been reading since deciding to try hammocking (and making a tarp)!

Happy Hanging!

Suzy :D

Good luck on your BlackCat. You will be hanging in bliss.

[Rapt]

Just decided to try out a Cat tarp based on the BlackCat design and instructions...

Then got thinking and figuring and such and ended up with a slightly different layout 144" ridgeline 54" half width with, a 90" parallel to ground length...(it doesn't fit the parameters of the spreadsheet calculator.) So then I had to calculate my own cat curves, (Excel is still easiest way to do this.) I based the curves I wanted on the apparent tension angles on the corners that I thought should keep the fabric taut without being limited to the approx 60 degree angle Blackbishop uses as a guideline.

As an aside: If you don't feel like doing the calculated curve method you can always hang a light chain or flexible heavy cord against your pattern material and simply mark the cat curve that way.

But before I committed a lot of time and material I wanted to be sure it'd still pitch reasonably tight etc. So I whipped up a 1/4 scale version from some scrap to see if it pitched tight. Seems pretty good. So I'm happy with the method I used to figure out the angles and curves. Will use it to tailor the tarp layout to my material exactly when I get a chance to measure the roll width. As it stands it'd work well with Tyvek material or narrower width cloth. Also saved myself a lot of work in cutting by folding the tarp material in half then in quarters. That way I make two cuts through multiple layers and all the cat curves are done in one pass. May not work so well on the full size but I'm going to entertain the possibility.

If I have success with the full size I may try another variation on dimensions so I can get an idea of how far we can push the long parallel to ground side... For those who want more coverage. With a few willing experimenters we might be able to generalize the cat calculator spreadsheet some more......

[lvleph]

Just decided to try out a Cat tarp based on the BlackCat design and instructions...

Then got thinking and figuring and such and ended up with a slightly different layout 144" ridgeline 54" half width with, a 90" parallel to ground length...(it doesn't fit the parameters of the spreadsheet calculator.) So then I had to calculate my own cat curves, (Excel is still easiest way to do this.) I based the curves I wanted on the apparent tension angles on the corners that I thought should keep the fabric taut without being limited to the approx 60 degree angle Blackbishop uses as a guideline.

As an aside: If you don't feel like doing the calculated curve method you can always hang a light chain or flexible heavy cord against your pattern material and simply mark the cat curve that way.

But before I committed a lot of time and material I wanted to be sure it'd still pitch reasonably tight etc. So I whipped up a 1/4 scale version from some scrap to see if it pitched tight. Seems pretty good. So I'm happy with the method I used to figure out the angles and curves. Will use it to tailor the tarp layout to my material exactly when I get a chance to measure the roll width. As it stands it'd work well with Tyvek material or narrower width cloth. Also saved myself a lot of work in cutting by folding the tarp material in half then in quarters. That way I make two cuts through multiple layers and all the cat curves are done in one pass. May not work so well on the full size but I'm going to entertain the possibility.

If I have success with the full size I may try another variation on dimensions so I can get an idea of how far we can push the long parallel to ground side... For those who want more coverage. With a few willing experimenters we might be able to generalize the cat calculator spreadsheet some more......

To get a true cat cut that chain/cord has to be very long. There is nothing in the excel sheet that I made that forces you to use the 60 degree thing. I added that, because it was for his directions. However, the measurements for a trapezoid of less than 60 degrees will still be there.

[Rapt]

Fair enough, I didn't "reverse engineer" the existing spreadsheet work so I wasn't sure, but without doing that the 60 degree limit was there. I just added my own worksheet to the spreadsheet, I find that's often as easy as trying to sort out what someone else did.

Besides as an engineer (there seems to be a lot of us technical types here) I like to work it out on my own...:D

Also maybe I don't fully understand the operation of the spreadsheet, but I couldn't get it to give me hex shapes (dimensions) like I wanted, even on the alternate dimensions page.

This is the basic dimensions I wanted to use, and putting in the parameters I can control on your input areas didn't give me the dimensions I wanted. http://i12.photobucket.com/albums/a230/rapt_up/Rapt_HEX.jpg (sorry its so faint) So I figured it was just as easy to calculate my own. :) What I did was figure out the angle I wanted at the tie out point, take the derivative of the curve (to get the slope or angle) and then adjust the parameter a to get approximately that angle. Then work out curve points corresponding to that value of a.

Or maybe I'm making this more complex than it needs to be.... LOL!

[stoikurt]

Yeah, probably more complicated than necessary for most of us. But if it's fun for you, go for it.

My first tarp was laid out like this. I only had 48" wide material so I sewed 2 pieces (48" X 11') together for an 11' ridgeline. I wanted 8' on the sides, so I just came in 18" from each corner and calculated or measured from the corner back up to ridge (simple right triangle). I decided (quite unscientifically) to use a 4.5" depth on the ends and a 6" depth on the sides and I used the Cat Curve generator to get all the measurements. It worked out pretty well, it's just not the tpe material and width that I really wanted.
http://www.hammockforums.net/gallery/showimage.php?i=280&catid=searchresults&searchid=1430
I've added some small tarp beaks to it since, but I really don't use this tarp since I made a BlackCat.
http://www.hammockforums.net/gallery/showimage.php?i=475&catid=searchresults&searchid=1430

[lvleph]

Fair enough, I didn't "reverse engineer" the existing spreadsheet work so I wasn't sure, but without doing that the 60 degree limit was there. I just added my own worksheet to the spreadsheet, I find that's often as easy as trying to sort out what someone else did.

Besides as an engineer (there seems to be a lot of us technical types here) I like to work it out on my own...:D

Also maybe I don't fully understand the operation of the spreadsheet, but I couldn't get it to give me hex shapes (dimensions) like I wanted, even on the alternate dimensions page.

This is the basic dimensions I wanted to use, and putting in the parameters I can control on your input areas didn't give me the dimensions I wanted. http://i12.photobucket.com/albums/a230/rapt_up/Rapt_HEX.jpg (sorry its so faint) So I figured it was just as easy to calculate my own. :) What I did was figure out the angle I wanted at the tie out point, take the derivative of the curve (to get the slope or angle) and then adjust the parameter a to get approximately that angle. Then work out curve points corresponding to that value of a.

Or maybe I'm making this more complex than it needs to be.... LOL!
The spreadsheet uses the assumption that the hexagon is regular, and so all of the sides are length a, while the ridgeline is length L. One inputs the ridgeline length and the width of one panel c, the spreadsheet then determines the length a that makes the regular hexagon. From there it uses that length a and a sag determined by the user, to figure out the catenary cut for each edge of the regular hexagon.

It wouldn't be too hard to adjust mine to work the way you want. All one would have to do is get rid of the a calculation all together. Have that as an input, then make an a2 parameter. Apply the newton's method function to the two edges. Then have it add a second graph and a second set of measurements.

However, it would be easier to just do one a at a time. Which, by the way, I have made a new catenary cut calculator. It can be found here (http://www.hammockforums.net/forum/attachment.php?attachmentid=443&d=1188932624). It just figures out the measurement based on a given length.

[wamyteipen]

Hey Lvleph, thanks for putting together these cat calc spreadsheets. I'm working on a cat tarp following BB's Blackcat insructions (thanks BB) but have made a few mods. Your spreadsheet is great for us non-math types.

[lvleph]

I taught lower level Math classes at a University, and so I know how some people feel about Math. I tried to make it as user friendly as I could.

[NCPatrick]

Hi lvleph, I'm with waymyteipen on this. Thanks for making it friendly for the non-math type people.

See this face? :eek: This was me in every math class, (except my face was usually red).

[hdbint]

Anyone else having a problem with the spreadsheet? When I hit "feed the cat" I get a VB Compile Error: "Sub or Function not defined". (It brings up the VB debugger....)

[Coffee]

You probibly have a different version of excel on your PC than what the program was written in.

PM me the dimensions you want with your email and I will send you the dimensions you need.

[hdbint]

Thanks for the offer HE.

Let me first ask this....The CAT cut is just an arc with the quadrant of the arc located at (1" x a) from the edge of side "a" correct? a=length of side a in decimal feet...hope that makes sense.

If this is true, I have AutoCAD and I can just draw it out. I plotted the CAT curve that shows up as the default in the spreadsheet and this is what it appears to be.

[Coffee]

I am going with sure.

My geometry is not as strong as it used to be. If you plotted it and it came up the same I would go with it. A lot of people are just bending a board and going with that. I think the important step is to get all the seams tight and straight.

[gunn parker]

A method I have used with success is to find the centre of your side, and then allowing 1 in for every foot of length; 1"x9'=9" measure in at the centre 9".
I then hang up my material on my fence so the material hangs down and is level at the top, I then attach a cord at both top corners of the material and let the cord sag in the middle down to that 9" centre mark.
I then get a marking pen and place marks along the material where the cord is and just follow the curve.

Works for me.
Gunn

[Nightwalker]

I'll see your guys' Calculas book and rasie you a linear systems design and Random Processes (Random Matrix stuff).

Scrooge it. My Machinery's Handbook gives every table and formula that I'll need. Plus, it makes a good door-stop/trip-over.

We should all have 5-pound plus texts. Makes people think we're intellurghent. :-)

[sir_n0thing]

Hey guys, pardon my n00bness, but I have a question I'm hoping someone can help me out with!
I'm brand new to the concept of camping in a hammock, and I'm looking to make myself a BlackCat tarp. I've gotten the PDF instructions and downloaded the Calculations.xls file. My problem is with the XLS file... In the PDF directions, it indicates a field to enter "c" value (width), and the directions refer to a diagram that should appear with dimensions. The XLS file I downloaded however ONLY has fields to enter length and a value to calculate the cat curve. It shows a graph of the curve on the right, but nowhere can I see a diagram or any other info regarding the general shape of the tarp! Is there another XLS file I missed, or has something changed, or...?
I love the look of Blackbishop's tarps, and would love to build one of my own for fun, but I am going to need all the dimensions.
Any help is most appreciated, and thanks for your tolerence of a new guy asking what might turn out to be silly questions! I'm really looking forward to trying out this whole hammock thing and possibly relegating my tent to the back of my gear closet!

Peace,

sir_n0thing

[Cannibal]

Somewhere, there is a thread where this was discussed. I was having problems viewing the current downloaded version too, but the solution was a setting. Can't remember for the life of me, maybe angrysparrow will shed some light on it.

[animalcontrol]

Somewhere, there is a thread where this was discussed. I was having problems viewing the current downloaded version too, but the solution was a setting. Can't remember for the life of me, maybe angrysparrow will shed some light on it.
maybe this thread (http://www.hammockforums.net/forum/showthread.php?t=3947&page=5) will help
different templates and calculators....

[sir_n0thing]

Wow, thanks for the response! No idea how in the heck I didn't spot that thread... but thank you again!