Davis VP2 w/ tilt-down anemometer mast

[gvmelbrty]

I've had this Davis VP2 station up for about a year, but haven't been able to post these pics until now.

I wanted to get the anemometer up near 33 feet, so I used the basic design for a tilt-over mast found at these sites: Tilt-Over Mast and WV7U Tilt-Over Antenna  … The main differences are that my mast support bracket needed to be non-permanent as I was planning to move to a new house at some point in the future and I added guy wire support to reduce high wind wobbling.

Here's the hole for the bracket foundation. It's 2' x 2' x 2' with some rebar.


This is the template used to hold four 18-inch j-bolts in the exact location while the cement was setting so the j-bolts would mate up with the bracket base plate holes.


The mast consists of square steel tubing. Lower section is 20' and upper section is 10', with a one-foot overlap. A round tube is welded at the top to accommodate the anemometer u-bolt mount, placing the instrument approx. 30ft high.


The bracket itself is two pieces of "L" beam steel, seven feet high, welded to 1/4" plate steel. The base plate sits on top of four large nuts screwed onto the j-bolts, allowing the mast to be leveled. Once leveled, nuts on the top side of the base plate secure the bracket in place (see diagram in post #6 below). The mast pivots on a stainless steel bolt near the bottom. For ease of wind vain alignment, the bracket was installed so that the mast points due north when down.


Copper lightening rod welded to the mast. Of course a direct hit would take out the anemometer electronics and the ISS located 30 feet away, so a rod probably serves little, if any purpose. One thing I have noticed, it draws birds away from the anemometer as they prefer instead to sit on the higher lightening rod perch. For protection, anemometer cable runs inside mast.


Walking the mast up. I don't have the steel specs in front of me, but I tried to get the thinest I could to keep the weight down, but at 30 feet, the mast is just barely manageable by one person - it's pretty darn heavy (with two people helping, it's no problem). If needed, I could use a come-along winch to lower (it's harder to safely lower than to raise). ... (I posted a lighter, safer design a few posts down.)


Top bolt to lock the mast in place.


Project finished. Station is located at 7400ft. Mast is held solidly in place with the help of three guy wires at the 21-foot level. The top will wobble only slightly above 40mph.



4"x4" ISS post located 30ft from the mast for optimal sighting purposes. Top of post is cut at an angle to eliminate rain splash into the bucket. Radiation shield is 5ft above ground level. Bird spikes protecting rain bucket is made from old metal fencing, held in place with a large hose clamp. The shelter behind the ISS houses an electrical connection for the rain bucket heater and a daytime fan-aspirated radiation shield (DFARS) converted to 24hr/ac power (coming soon).


The cable connected to the Davis anemometer is 40ft long, so I needed an extension cable to get it to the ISS. I made one from outdoor-rated CAT5 twisted-pair and just as an experiment, instead of soldering the wires together, I left the RJ-11 connector intact and used an inline coupler to connect the two runs together.


The junction is sheltered inside an outdoor extension cord box. So far, there have been no problems with this connection, through one winter and summer. Exposed cable leading from the mast to the ISS is protected by plastic split-flex tubing (that was recently damaged, possibly by a rat or squirrel).

[PaulMy]

Excellent work

Paul

[gvmelbrty]

Excellent work

Paul

Thanks. It was a lot of fun planning and putting it all together.

[CNYWeather]

That's a great installation!!

Very ingenious.

[vaughanweather]

Thanks for the post! I love this method of getting the mast way up there!

I might be using this method in a near future install. I was going to rent a scissor lift but you may have just saved me from doing so!

[Skywatch]

Going to be a while but I'm thinking of rigging mine up on one of those. Taking down my partly corroded tower can be a pill.

[gvmelbrty]

For anyone considering making a tilt-down bracket similar to mine for their weather station, I thought I might propose a more simple design that requires no welding for permanent installations and some welding for a portable version.

The total cost in materials for just the bracket seen above was around $125. A friend donated welding skills, otherwise welding costs would have added at least another $150. Cost-wise, this new design will end up being in the same ball park.

At $195, the main expense will be the ATK65 telescoping aluminum mast. The best part about this mast is that all 65 feet weighs only 18 pounds! And if you choose to use just a few sections of the mast to get it up to 33 ft, the weight is even less. This makes tilting a very easy and safe one-man operation.

DX Engineering makes a pricey tilt bracket just for this mast. This video demonstrates its operation. But if you'd like to save $160, here's another idea…

No matter what tilting mechanism you choose, you'll need a base pole to mount it to. For a permanent installation, you can use an eight or ten-foot, 2-3 inch diameter galvanized steel pipe, Schedule 20 or 40 steel pipe or square steel tubing. (Since the ATK65 is so light, you could probably get away with using cheap electrical conduit, but I wouldn't. Be safe and use steel pipe.) Cement at least a third or more of the pipe in the ground. For a 10ft pipe, if the ground is forgiving, I'd bury four feet. Now, drill a pivot bolt hole in the pipe 8-12 inches above the ground (you'll probably want to do this before you plant the pole). Drill a similar hole in the bottom section of the aluminum mast. The only thing left is some sort of locking plate near the top to hold the mast in place. You could use steel straps or a long u-bolt. Adjust locking mechanism to level mast on the y-axis and add large washers between the two poles at the pivot bolt to level on the x-axis. Choose a sufficiently long enough pivot bolt to allow for the addition of leveling washers (hopefully none or just one or two are needed).

If you go above 20 feet or so, you'll want to use guy wires to keep your anemometer from wobbling in high winds.

Single-pole tilt-down bracket:


A portable version of the mast support bracket (see original post for more details) could use a five or six-foot piece of square steel tubing welded to 1/4-inch plate steel, supported by four gussets.