I am hoping to begin setting up a weather station this coming week and need to come up with a semi-temporary mast solution. Can anyone commentary, give rules of thumb, or some links to guidance or “worked” examples? I have checked out those referenced here but none correlate well to what I would like to do.
What I am wanting to do is use a 20’ section of ‘black iron’ or galvanized water pipe fastened to a 6" beam supporting part of my deck in an unguyed configuration. The beam is 10’ long from footing to deck level and well supported top and bottom. I will place a short piece of PVC on top of the iron pipe section to mount the wind sensor. I may also place one or two small antennas on that mast also. That will depend on the stability of the setup with just the wind sensor.
I have 2 specific questions.
What diameter pipe is best (cost/performance)? I am thinking minimum 2.5 in. Smaller would be ok if performance (stability) is adequate.
For a given diameter, how many feet should be supported by the beam? I am thinking that 5’ of pipe supported 3 places would be ok. Is that reasonable? We have had gusts in the area exceed 70 MPH and the location is very exposed so I need an reasonable margin for really nasty weather.
Any input would be appreciated.
I have a full sized VHF/UHF TV antenna on a 20 ft length of 2.5 inch Galvanized water pipe. The pipe is about 2ft into the ground and supported by a deck beam at about 9 feet. The max wind recorded since it has been up was 45 mph, but that antenna has a lot of wind resistance. The pipe is very heavy and tends to flop just due to its own weight. It would do a lot of damage if it fell, I would have used a thinner wall if I could have found any. I can’t recommend it as a good solution, and in your situation I would feel more comfortable with a guyed solution with a lighter mast/pipe. Do you really need to go up to 20 feet? My anemometer is on about 15 feet of about 1.5 inch galv tube that’s sold as top rail for fencing, it’s pretty light and the ends of the pieces are swaged to fit together. It’s supported about 7 feet above ground but not guyed.
I would recommend not the most heavy pipe you can lug in with a team of wild pack animals.
[quote author=aardvark link=topic=5972.msg39278#msg39278 date=1099279002]I would recommend not the most heavy pipe you can lug in with a team of wild pack animals.
It looks like you have a good handle on that pipe there, yep looks like a winner to me :lol:
2" aluminium (aluminum for our US readers) is usually sufficient as long as it’s fairly thick walled. The only thing you might find is that it’s a bit springy if you’re using very long lengths. My anemometer (and a 2m/70cm vertical antenna) is on the top of a 15ft Al pole that I think it 1.75".
Don’t forget the fixing sizes…the mast clamps for my anemometer only just fit (with some bending) round the pole I used, so you’ll probably not get them round a 2.5" pole!
I used to buy all sizes of aluminium (:lol:) antenna pole in the UK, but for some reason it’s just not commonly available here About the only source I found of Al pipe is “rain for rent” who sell irrigation stuff.
Thanks for all the input. everyone.
Niko, I couldn’t agree more! I have no interest in the caber toss (or activities that resemble it) other than as a bystander. This install lends it’self to hinging the mast at the base (like some sailing masts I think) and using a come-along (manual winch) to control raising and lowering of the mast. The cable would run from near the ground at the base of another deck post, over the top of the post at the upper attachment point to change the direction of pull as the mast goes closer to horizontal. I hope that is clear enough. As to the aluminium, It would be my preference also or poss. AL ? coated steel. The main concern is what is a safe and stable unsupported length for a given material, diameter, and thickness and what portion of the overall length should be attached to the support structure? I REALLY want to avoid guy lines!
Admin, I haven’t, I was planning on a transition to PVC and reducing to the requisite dia. Using other kinds of materials may raise the issue of transitions also, not that it would be a showstopper. I have in mind the requirement to use stainless when in contact with aluminum to prevent galvanic corrosion. Is the 15’ span the unsupported portion, or the over all length.
Also, 20’ (actually 21’) is the mast length overall (longest material I can get in 1 piece) .
Keep the input coming!
Im using a 1 1/2 into 2 inch pipe, i think 3mm think wall.
12 x 12 inch mild steel plate with 4 threaded rods in 2 feet of cemet.
more images at www.gorgecreekorchards.com.au/aboutus.html
in theory you really want your rain gauge 30cm off the ground only…
but in a orchard, it would then get irrigation?
i use under tree sprinklers
Have a look at this website http://www.nws.noaa.gov/om/coop/standard.htm
yeah, the idea of being close to the ground is to lessen the loss from wind driven rain…
but then when you are close to the ground, you also need to keep it away from other structures that would shelter it…
in your case , its OK to have it on top of the pole…
I have my anemometer mounted about 15’ high on a piece of PVC pipe.