I went ahead and built some little models to scale out of some foam board and wire to make it a little easier to show what I'm talking about, and also so I could huff and puff and try to blow them over to test how stable the design actually is. I don't know how accurate my "huffing and puffing trying to blow them over" test is or if it even applies to real world conditions, but it was harder to blow them over than I thought it would be, so I'm satisfied they'll work.
It's easier to look at the photos than it would be to draw and explain my plans, but the relevant measurements are:
-the windbreak (foam board, sheet metal, wood, etc.) part is 8'x24',
-the width of the base needs to be 1.5 times the height of the windbreak for stability, so the legs are about 12' long,
-the lines on the foam board represent the framing that the sheet metal is attached to,
-there is about a one-foot gap at the bottom for enough air flow (it has something to do with snow drifting),
-the pipe at the top is so that a tractor with a bale spike can be used to pick up and move the windbreaks.
-the legs are removable and are simply a 2 3/8 pipe slid into a 2 7/8 sleeve (the Ranchers.net forum post has a picture of the assembly).
Since the windbreak has removable legs and is about 8' tall, I should be able to easily disassemble and load them onto an equipment trailer so that they can be moved longer distances (which is one of my design criteria).
|Two windbreaks attached together and angled for more wind blocking action|
|Legs need to be 6-feet from the ends so the windbreaks can be angled|
|Three windbreaks attached together for even more stability and wind blocking|
The material used to make the windbreak itself also needs to be decided. Some sources recommend something like 2x6 lumber spaced a couple of inches apart to make a porous windbreak which is supposed to have an advantage over a solid wall (try going to the Portable Windbreak Fences publication for more info). Wood seems like it would be heavy, more expensive, and less durable. If I could salvage some treated boards from somewhere, it might be an option.
I've also read about using used billboard tarps (available on eBay for reasonable prices) on a windbreak, which sounds like it would work reasonably well although I'm not sure how long a billboard tarp would last or what it would look like out in a pasture if the printed part of the billboard tarp was still visible.
Solid sheet-metal (the same as on a barn) is another option, which at the moment, is the type of material I think I'd probably use for building a windbreak. Sheet-metal is relatively light weight, pretty durable, and is affordable. Sheet metal should also make it easier to move them on a trailer if I ever decide to. I'm undecided about whether I'd run the sheet-metal horizontally or vertically. The framing would need to be built differently depending on how the sheet metal is installed, so I'll have to do some thinking on what would work better, would be easiest to build, etc..
So far, I think that explaining in detail how I'd build my version of a portable windbreak might possibly be the extra shove I need to build one or two this winter, so stay tuned for the possible, maybe, if-I-ever-get-around-to-it building process (I'm still not making any promises though).