Why not a tetrahedron tent?

[Dwight Shackelford]

I’ve been playing with folded paper at work when I need to distract myself for a moment.

I’ve come up with tetrahedron shaped tent that can be made from a piece of fabric twice as long as it is wide. Its not a completely enclosed tetra, but the remaining opening can either be enclosed with a door straight across the opening, or some vestibule flaps could be sewn on to complete the shape.

Here’s some reasons I can think of for not going this route:

1) the tetrahedron has the highest surface to volume ratio of the geometric solids.

2) use of floor space is probably very inefficient, being either a parallelogram, or a triangle.

Reasons for:

1) simple. No seams except at the flap.

2) could form a poncho/tarp, though I’d have to cut one out and drape it to see what that is like.

3) I came up with it (though I’m sure its not original), and its like cooking bad meals, “You made it, you eat it” or freeze in it, or whatever.

4) Might be a highly wind resistant shape.

5) Might be a very stable shape.

Any ideas?

[Vick Hines]

You are definitely on to something. That is the shape created by the simple 5×8 cape/tarp I use when I am on the ground instead of hammock. As you have learned with the paper, the back forms a triangle. However, if you want a rectangular floor, the sides need to intersect the back at an angle less than 90 degrees, depending on the slope of the back.

Try this full scale with a plastic drop cloth and duct tape. That way, you can actually see how it works for shelter. I think you will like it.

If you make a cape instead of a poncho, you won’t have to worry about leaks around the hood.

If you want a more “developed” tent, you can add door flaps with a beaked pull-out over the intersection of the flaps at the top. The flaps can form a sheltered ‘vestibule’

Pardon the pack explosion. This is the cape set up as a shelter. A 5×8 rectangle of fabric makes a shelter 8 feet long and 3+ feet wide with plenty of sit-up room.

The hood forms at the center of a long edge using fasteners set 6″ inboard of the hem matching fasteners on the hem. No hassel making a hood and no hassel with leaks.

Why not experiment with a more ‘shaped’ shelter along the lines of your half pyramid that could also be used as a cape. I havn’t tried it, but I’ll bet it would work.

[Dwight Shackelford]

I could be wrong, but it seems with the half pyramid, I’m going to have to be making seams, given a max of 58″ fabric width I’m dealing with. I can make seams, but I don’t trust my current experience with seam sealing, with is limited to putting silnet on a commercial tent which was not silicone impregnated.

I just cut out a little scale tent, and scale “me”, a mini-me. However, I’ve only got 8″ vertical height on mini-me, and my feet are 11″ long, so I might have to adjust.

What is a reasonable vertical height for a comfort zone in a tent? 12″? I’m talking about when you’re lying down.

[Dwight Shackelford]

Yeah, cape is what I had in mind, not a poncho.

[Sam Haraldson]

I’ve got to be honest. I don’t find true comfort under a setup unless I can sit up in it. Now, this is of course COMFORT we’re talking about here. However, if the meaning of comfort at the time is being dry, then just laying down under 12 or 18 inches may be comfortable.

Ideally, however, when it’s tarp setup tiem i shoot for three to four feet of headroom at one end if I can so that I can comfortably situp and take off my shoes, cook, et al.

[Dwight Shackelford]

What I’m talking about would have 36″ at the apex. That’s for a 5×10 tarp. If you go higher, you start losing too much floor space. And that’s also strung with the bottom edges on the ground. If you suspended it, you could get more headroom.

[Dwight Shackelford]

Sam,

Ok, now I see what you’re talking about. I was talking about, when you’re laying down, how much room do you want to have away from the angled in walls. That’s assuming sleeping towards the back wall of the tent, with your head and feet approaching the angled in side walls.

There would be 36″ of headroom at the entrance. Sorry for the confusion.

[Sam Haraldson]

Ah, I see, Dwight. I was trying to figure out what sort of masochist you were that would only need 12 to 18 inches of headroom in their shelter! This clears things up significantly.

[Dwight Shackelford]

I had a very bad accident as a child with an old wringer style washing machine.

Good thing is, bars will never hold me. ;-)

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