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Re: [TowerTalk] Guying Lengths Revisited

To: "jknodel M Knodel" <>,
Subject: Re: [TowerTalk] Guying Lengths Revisited
From: Jim Lux <>
Date: Mon, 24 Jul 2006 14:01:29 -0700
List-post: <>
At 12:27 PM 7/24/2006, jknodel M Knodel wrote:
>Greetings all,
>Thank you to all those that have answered my previous tower questions.  My
>project is still in the works and I have yet another question...
>Do you think it would be feasible to guy a Rohn 25 tower at less than the
>specified 80% and still have it be a "safe" installation?

Safe is in the eye (and pocketbook) of the beholder (and, possibly, a 
regulatory agency).

If you don't need to get a building permit, etc., and it's strictly up to 
you, here's a variety of spreadsheets out there that can calculate the 
loads for you, and you can compare that against the design loads, and make 
your own judgement call.

If you have to get a permit, they may well want some more rigorous 
analysis, perhaps by someone licensed, although, some jurisdictions will 
take your personal calculations, if you're doing the work (the usual sort 
of homeowner exemption) and it's on your property.

>I would like to put up 60' and guy it at about 60% (36') or even 50' and guy
>it at 72% (36').  I could guy a 40' tower to the full 80% but of course,
>would like to go higher with limited space for guys.

So, what you want to do is bring the guy anchors in closer?

What that does is increase the tension on the guys in a wind load, so you 
might need stronger guys, and more substantial guy anchors (so they don't 
pull out), and more base for the tower (so it doesn't sink into the earth). 
Might is the operative word here, and that's what the calculations are for.

On a moderately tall tower, the tower itself often contributes more wind 
load than the antennas, although the antennas ARE at the end of a big lever 

Jim, W6RMK 


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