[TowerTalk] Temporary guys

[Mike Ryan]

Some people don't get it. - m

-----Original Message-----
From: towertalk-bounces at contesting.com
[mailto:towertalk-bounces at contesting.com] On Behalf Of Grant Saviers
Sent: Sunday, April 03, 2011 12:21 PM
Cc: TOWERTALK at contesting.com
Subject: Re: [TowerTalk] Temporary guys

Use a large enough nylon rope (5/8 - 3/4") and you might be ok.

However, think about what the rope tension becomes as a section of tower 
gets out of vertical.  It is impossible to pull a horizontal pole 
upright with a rope parallel to the ground - it takes infinite force.  
As the temp guyed section starts to lean (worst case directly opposite 
one guy) the tension starts to increase towards infinity, the rope 
stretches and the tower leans more, until down it comes.  Nylon rope as 
the other two guys are a long spring helping to pull the tower over!  
Think of EHS and wire rope as a very short spring.  The tension is gone 
as soon as the tower moves a few inches (except for the weight of the guy).

The perfect (worst case & likely) setup is you at the top, tram lines to 
slide the beam up, and gin pole above the tower top to hoist the beam 
onto the mast, all adding more load force against a single guy.  The top 
guy on a 90' tower is 115' long so 8% or 10' of stretch swings the top 
30 feet out of column 10' and down it and you and beam and gin pole comes.

There is a great tower stress analysis at 
http://wiki.contesting.com/index.php/Guyed_tower_study   It explains a 
lot about how tower/guy systems behave.

Grant KZ1W

On 4/3/2011 7:32 AM, john at kk9a.com wrote:
> I use nylon rope all the time for tower work and for supporting temporary
> antennas and I have never seen the stretch that you describe Roger.
> Actually I like a little stretch when installing large antennas as it
allows
> for a little height adjustment while on the tower. According to the
> internet, nylon rope stretched 10-15% when under a load equal to 30% of
it's
> breaking strength.
>
> John KK9A
>
>
>
> To: towertalk at contesting.com
> Subject: Re: [TowerTalk] Temporary guys
> From: K8RI on TT<k8ri-on-towertalk at tm.net>
> Date: Thu, 31 Mar 2011 00:27:02 -0400
> List-post:<towertalk at contesting.com">mailto:towertalk at contesting.com>
>
> On 3/30/2011 6:13 PM, john at kk9a.com wrote:
>> I am curious how temporary guys could stretch so much to lay a tower on
>> its
>> side, perhaps the guy anchors were very far away?   The Trucker's Hitch
is
>> great advice, I have used this knot to for securing tower or reels of
>> hardline when transporting them home.
> When experimenting with a phased array I used Nylon rope to guy a
> temporary 40 meter vertical made from relatively light weight steel
> masting (the old TV masting). In 24 hours that antenna was leaning a
> good 60 degrees from vertical. You could walk over and take hold of the
> top.
>
> Nylon does not make even a good temporary solution to holding an
> antenna.  However after it's been stretch out in the elements for a
> couple of weeks there is very little stretch left. OTOH I still would
> not trust it.
>
> 73
>
> Roger (K8RI)
>
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