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Re: [TowerTalk] Temporary guys for FD towers

To: Derek Cohn/WB0TUA <>
Subject: Re: [TowerTalk] Temporary guys for FD towers
From: "Roger (K8RI)" <>
Date: Sat, 09 Aug 2008 23:22:00 -0400
List-post: <">>
One of the things to remember about FD is it is a *temporary* operation 
so we don't use the kinds of installations we'd use for something 
permanent, BUT we still can't sacrifice safety. However to me that is 
not installing for 100 MPH survival or even 70.  I consider any one who 
stays out there in the tents when the wind gets much over 40 to be nuts 
any way. <:-))

I may be going against some of the conventional wisdom, but I do have a 
lot of experience with this type of tower arrangement.
My only comment with Nylon rope is don't use it for guying in situations 
like this or for the only guys.  (I've used it to guy an AV640 on top of 
a 40' tower" but that is quite different than guying the tower)  Braided 
Poly rope which is actually cheaper in some instances is stronger, or 
can be stronger.  3/16" is about  600# test.  5/16"  is 800# and 3/8" is 
about a 1000# and has very little stretch. My personal preference would 
be galvanized wire rope, or the 3/16" Phillystran.    Just remember that 
wire rope varies widely in strength and quality.  A 40' tower with a 
TA-33 doesn't present a large wind load (over turning moment) even with 
40 - 50 MPH winds at least when all else is taken into consideration.   
As to Manila rope, the only rope of this kind I'd ever use would be new 
and of at least 3/8" or preferably 1/2". As has been mentioned, it ages 
and can deteriorate rapidly. I've used large  Manila rope in farming 
operations and have had several close calls. I always treat it as if it 
is going to break. Taking that approach I've never been hurt using it.  
OTOH I've seen large Manila ropes break under less load than they were 
normally subject.  They can make a great slingshot!

The tower base: normally serves to keep the tower from sinking in the 
ground or as an anchor point that won't slide out from under it and 
*normally* adds little to the over turning strength presented to the 
tower by the guys. Again with small loads (short towers and small 
antennas) this usually isn't much of a problem.  25G is not considered 
self supporting and certainly not 40' of it so the purpose of the base 
is again to just hold the tower in place.  The flat, hinged baseplate 
(BPH25G) certainly needs something to hold it in place. For temporary 
setups my choice would be either the  drive in base (SDB25G) or the 
drive in rods (DR25G), but you do have to remain conscious of what's 
under the surface and athletic fields may have all kinds of things "down 

As to the guy anchors, I've used standard, drive in fence posts although 
they should have additional flat plates welded on the part going into 
the dirt and be driven in deeper than normal. The guy lines should 
attach at ground level with the post driven in perpendicular to the guy 
line. Note, if some one does use fence posts like this they can be 
*dangerous* objects you can walk into and get hurt seriously.  I had a 
couple in the yard temporarily. They had foam rubber wrapped around the 
tops to about 2" thickness and that was wrapped with bright Yellow tape 
for visibility.

At FD we've used the standard "screw anchor" just like they use for 
tying down airplanes. They are 18 to 24" long and look like a cork screw 
with a triangular handle. These are strong enough to hold a tower like 
you describe *IF* the soil is strong enough.  Here the soils is at least 
as important as the anchor.  I've used 3' pieces of 3/4" pipe to screw 
them in and a 4' piece to get them out, but this was in clay. In sand or 
light soil they'd be next to useless. NOTE like many other things the 
quality and strength of these screw anchors varies widely and is 
probably proportional to the price.

Another important point about the soil is what happens when it gets wet? 
Good old fashioned clay only gets gooey at the surface while clay or 
sand loam may turn to goo with very little strength far enough down to 
affect the integrity of the anchor.

Sooo... For me, I'd make up a set of drive in rods for the tower base 
along with a template to keep them aligned and they are a bear to align. 
I'd also make up a set of drive rods with flat plates for guy anchors 
along with a tool to go over the end so they can be driven without 
damage.  Depending on the soil 2 to 2 1/2' penetration would be plenty. 
In some cases you'd need 4'.  I'd also make up either pre cut wire rope 
or Phillystran guys with turn buckles. I'd not worry about the steel 
ends we normally use for permanent installations, but don't build a camp 
fire next to one.  Phyllistran is expensive, but the 3/16" is 1200# 
test, it's light, and easy to handle.  OTOH you do have to use cable 
clamps on it and can easily damage the cable with improper installation.

To me, Tower height, plus 50% is normally sufficient safe distance, but 
it depends on what you put on the tower.  Let common sense be your guide.

Roger (K8RI - ARRL Life Member)
N833R (World's oldest Debonair)


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