3 tower cables instead of four

[windpolywog]

I am in the process of installing the concrete for a 45 foot tall tower, with a 13' diameter windmill.  I decided to put in 3 cable anchors instead of four, and wanted to get feed back to see if the fourth cable is really needed.

A little about the anchors.  I drilled the three holes 35 feet from the tower base in an evenly spaced triangle around the base of the tower.  Each hole is 30" in diameter and 5.5 feet deep.  The holes will be filled with concrete and rebar.  The hole that the windmill base will sit on is the same dimensions.

I am using a 45' light pole, 10" at the base and 4.5" at the top for my tower.

Does anyone have any feed back?

Thanks!!

[wpowokal]

You do not say if this tower is to be tilting or not, if it is to be tilting then four guy wires are required.

For a tilting tower, you raise and lower with one set, the oposite set stops it falling on you when raising, and the two side sets stop it falling sideways.

allan

[phil b]

I think Alan is correct. I have experience with 3 and 4 wire guyed towers.

If you plan to tilt the tower with anything heavy on the top, I would use 4 wires. The 2 wires at 90 degrees from the direction you will be lowering it from will help guide the tower up and down. On my generator towers, I loosen the 90 deg wires slightly so they will not put the tower in a bind when raising and lowering. Nothing is level on my property.

I also work with weather equipment frequently that's mounted on 10 meter (33ft)towers. 3 guy wires are normally used on these aluminum lattice type towers and they are really light. They do have very strong hinges and a lot of concrete where they are attached to the ground. The load at the top is less than 5 lbs. 2 men can raise and lower these towers with little trouble.  

Some large towers have 3 guys and they use cranes to service them.

Why don't you try an experiment? Attach 3 guy wires to the top of a 5 to 10 foot pole and stake them to the ground. Make a hinge point for the tower on the ground. Hoist it into the air as you would do with the larger tower. Next put 4 wires on it and hoist again. See which is works best for you.

Hope this helps.

[Mary B]

Almost all amateur adio towers use 3 guys, but these are commercial towers that will move very little if any when they are being tilted up. I had 35 feet of rohn 25 behind the house (had to take it down for the new deck) that was tilt over. No guys at all, it was house bracketed at 25 feet and had about 150 pounds worth of antennas and other hardware on top. If it is just a mast then yes go with 4, if it is a normal tower with the factory tilt base 3 is plenty.

[wpowokal]

Phil, the two 90 deg guys do not have to be horozontla(level) all you need is a line of sight from one to the other through the piviot point.

Allan

[windpolywog]

Thank you for your response:

It will be a tilting tower.  I am making a hinge similar to the hinge used on the new southwest windpower skystream tower.  I am thinking I will tilt the tower up with one cable and the other two will stop it from falling on me.  

I will point the hinge to face directly between the other two cables.

Do you agree?

[jmk]

 You better do the experiment. You can lose your tower and mill with three.

[wpowokal]

No I do not agree with you because once you start tilting away fron vertical the remaining two guys will get progressivly slacker to the point where the tower will fall. The exception to this may be towers that are basicall self supporting, even then with a generator on top things will be scarey. I should add here they generall bend not actuall fall over sideways, same sinking feeling though.

You have not mentioned your proposed tower construction and I am unfamiluar with the piviot you describe, although I don't see it could make any difference.

My 20' test towers (for small units) have only 3 guys, I physically push these up, and I do know what the guy wires are doing. As others have said do a simple test.

Allan down under

[wpowokal]

Ops just re-read your post you do describe your tower, apologies for my missing that.

allan