MYOG Pyramid

1 – Catenary curve will make the tent pitch more taut. It'll flap leass in the wind. Not that difficult if you use that spread sheet. Report back the calculations for lengths and I'll double check them.

2 – Fold netting over 1/4 inch twice and sew it to silnylon. To join pieces make a flat felled seam.

3 – You try making a prototype to try out size. You could make it out of plastic, or you could just use some twine – run it from peak to 4 corners – get inside and try it out to see if it seems big enough. The taller the tent is the more susceptible to wind. Most people have tents that are 40 inches tall and do fine, so 60 inches may be fine, even for 4 people. What is the maximum length of one trekking pole? How flimsy would it get if you connected two together?

Thanks for the info! This is very valuable.

I assumed strapping two trekking poles would be strong enough, since that is what MLD and Oware say you can with their pyramids. That is a great idea on using twine to figure out the correct size. I'm just a little paranoid about touching the sides of the shelter with all of the condensation with previous experiences. I hate soaking my down bag.

There's been at least one thread recently about connecting two trekking poles

My first project was a MYOG 10×10 pyramid. It did not use cat curves on mine, and would recommend just using straight sides to simplify it. I think that I made it a little over 6' tall since I am 6'3". Even at that height, 4 guys with gear would be tight. I have tried to join 2 Leki ultralight trekking poles to support it. It worked OK, but there was alot of deflection. Mostly because these are 130cm poles and they are not quite as stiff as normal poles. I think that if you have normal 140cm poles you would be fine to use them for the support.

Also, for the peak reinforcement patch, I used some uncoated ripstop, and that worked out well. I had it out in a blizzard once in the back yard to test it, and it did just fine. I modified it after using it a few times by shortening the long diagonal sides about 6". This helped in getting a tight to the ground pitch. Otherwise, the middle of each side tended to be up off the ground a few inches.

I have some google sketchup templates I cam send you of several pyramids if you use that program.

Good luck

Thanks Ben for sharing.

I did a rough mock setup using string in my basement. I made it about 10×10 using a height of 65 inches (2 inches off of the ground), and it seemed like it would fit four guys with gear without a problem. At this point I probably will go with a height of 68". I think the fact that silnylon stretches will just require me to tighten everything up before I go to bed in the shelter.

That is good advice on the trekking poles. If it doesn't work, than I will probably just get a carbon pole made for this.

Looking at the designs for doing a cat curve, doesn't look like it will be all that difficult. I have a lot of time between now and when I would use it, so I think I am going to take my time in making stuff sacks and other things so I can become more comfortable working with the fabric.

It would be great if you could send me some sketches of the pyramids you made. My email is roanefamily at gmail.com .

Is there a certain type of thread I should plan on using for sewing everything together?

Jerry: After re-reading your tutorial multiple times, the only thing that I am not sure on is how the eight pieces form the shelter. Does the catenary curve form the ridge between the four tent stake loops and the apex? So basically the seams would be in the middle of each side and then the four ridge lines?

Chris,

I am planning on making almost exactly the same pyramid as you, down to the bug netting. I am about to order materials from OWF (but will probably take a while to start sewing). Please keep posting on your thoughts and progress, particularly on the center height, as I've been wondering the same thing.

I plan to use a catenary curve, seems simple enough.

I'm considerning additional ventialtion at the peak but haven't come up with anything I like yet, I may not bother in the end.

I'll post something eventually…

"Jerry: After re-reading your tutorial multiple times, the only thing that I am not sure on is how the eight pieces form the shelter. Does the catenary curve form the ridge between the four tent stake loops and the apex? So basically the seams would be in the middle of each side and then the four ridge lines?"

Yes

There are 4 seams on 4 ridges

and 4 more seams on the middle of each side

The 4 ridge line seams are catenary curves

Thanks Jerry!

I put in 103.02 inches for the ridgeline in the excel spreadsheet (based on the calculations in the article) for calculating the catenary curve length, but the graph x plane doesn't fit the diagram. But it looks like y cm column still calculates, so I will just use those values.

Now how exact does the catenary curve need to be to be mostly effective? I'm just wondering how I am going to measure 4.606 cm (as an example) to make the cardboard/wood template in your article. Can I just eyeball it or do I need to find a measurement tool that measures to the thousandth cm?

The more I work on this, the more confident I become in knowing that I can do this!

if you have a mm ruler you can use mm (which are tenths of a cm)

don't need any more accuracy than that

I just spent 7 nights in my old Megamid, and would second Ben's comment.

The thing no one ever seems to mentions about pyramids is the bottom mid-point tie outs. If you make the base square, these are always up in the air. (although this may self correct somehow with a cat curve, I'm not sure.) You can see this on the MLD site here
http://www.mountainlaureldesigns.com/shop/images/2010sm2.jpg

It makes it hard to batten to the ground if you want/need to.

I would plan on making the centre seams of the large panels about six inches longer than what's needed for square. Then you can play with the shape once you have it up and pitched. A cat curve from corner to mid-base would be the most elegant. If you want to be really tricky, you could add a second pegout point six inches back up the centre seam, to allow it to pitch with the sides somewhat raised.

"The thing no one ever seems to mentions about pyramids is the bottom mid-point tie outs. If you make the base square, these are always up in the air."

I had tieouts on the middle of each side of my puramid.

During a windy period some of the stakes for these middle tieouts pulled out.

The thing is, at the corners the tent pulls more sideways on the stakes and has a constant pull.

On the middle, it pulls up more on the stakes, and it flaps around so sometimes there's no force on the stake, then it really pulls on it. It would help to drive in the stake more at an angle, than verticle.

But, duhhh, if the middle stakes pull out and the tent stays erect, then I guess you don't need those stakes.

It would be easy enough to put the loops in, and wouldn't add much weight, and then you could use them or not with experience.

I don't think you need to put cat curves in the middle. The silnylon stretches so the cat curves on the ridges will result in it being taut in the middle also.

Yeah, the middle points are up in the air a little, but that's fine because it lets in a little air to minimize condensation.

For those of you who are interested in following my progress, I created a new thread that posted details in what I am going to go with. This is also where I will post updates to what I end up doing as I get farther into the project: http://www.backpackinglight.com/cgi-bin/backpackinglight/forums/thread_display.html?forum_thread_id=42299&skip_to_post=359680#359680

I agree Jerry, ventilation is great, but when you get 10 inches of rain in 24 hours and winds at a gusty 10-25mph, it's nice to be able to batten down on the windward side!!!