A 60 foot Irrigation Tubing Mast/Vertical
N6RK, March 28, 2004
Here are some photos of my workhorse 60 foot mast design, made from 3 inch aluminum irrigation
tubing (0.050 wall). It is a junior version of the 90 foot vertical described elsewhere on this
site. A ginpole or "falling derrick" of 2 inch irrigation tubing 30 feet long is used to tilt up the 60 foot mast. The 30 foot derrick can simply be walked up. No sophisticated pulley designs are needed; I simply pull it up with a rope in about 10 seconds. As you can see in the just lifting off photo and the almost vertical photo, the tubing bends quite a bit. I may replace the 2 inch derrick piece with a 3 inch one to reduce bowing, but I haven't gotten around to it yet. Nevertheless, it has been up and down dozens of times without mishap. Actually, I am more worried about drivers on the nearby road looking at this thing being raised, getting distracted, and having an accident, than I am about the tubing breaking. I've heard drivers saying comments along the line of "what the heck is that thing???"
A hollow wooden ground structure is buried to provide pivots for the mast and derrick/ginpole.
First, a hollow post is constructed by making a box from 4 pieces of 2 inch thick lumber. Then a superstructure is added to it with 1/2 inch carriage bolts acting as pivots. Finally, it is buried in the ground as shown here.
Guying is done with UV-proof polypropylene baler twine available at ag stores and ag equipment dealers.
Real cheap, 9000 feet is $35. Tip: tell the guy at the ag store counter you want to tie trees with it, not bale hay. Don't confuse him by talking about antennas.
I use this mast design for inverted vees and verticals (six of them for 80 meters). For the verticals I use 2 inch tubing for the top 30 feet, since it doesn't have to support anything.
A lot of information on aluminum irrigation tubing can be found at http://www.rainforrent.com/products/pipeline.htm. If you live in California, you can buy tubing from one of their stores. They will deliver for an extra fee.