[TowerTalk] Mast wind loading

[Doug Renwick]

You are to be commended for sharing your experiences and I
agree with your philosophy.  A lot don't share their
experiences because they get chastised by people who throw
around words like 'unsafe'.  Have these people ever heard of
'risk analysis'?  Really...how much will your tower
withstand can only be determined by 'product testing to
destruction'.  If your tower arrangement has survived for 25
years then IMO you have a safe installation.  Great job!

Doug/VA5DX

Subject: Re: [TowerTalk] Mast wind loading
>  Hi All,
I have been biting my tongue for years about the
theoretical load of Rohn 
towers.  It may be important for building  code purposes and
surely is for 
Rohn's litigation exposure, but in the  real world it is
really unimportant. 
A properly installed and guyed Rohn  tower will hold MANY
times more than 
indicated in the catalogs.  I  look at the pictures of Rohn
25 with a single 
beam at the top because of  "loading' and I laugh.  Here in
the Northeast 
there are dozens, if  not hundreds of big contesters with
super-loaded towers 
for years without  any mishaps, except for the ocassional 2
inches of ice and 
50 mph winds  together. My 100 foot Rohn 45 tower has a 15
foot, 3 inch moly 
mast with a  4 element homebrew 15 meter beam on a 35 foot
boom and a 4 
element  homebrew 20 meter beam on a 57 foot 3 inch boom.
At 80 feet I have 
a  2 element Cushcraft 40 meter beam, at 68 feet I have a
TH7DXX, at 50 feet  
I have a homebrew 6 element 10 meter beam on a 27 foot boom,
and 34 feet I  
have another TH7DXX, and at 70 feet I have a Ringo Ranger II
vertical. You  
calculate the wind loading!! It's been up for over 25 years
without any  
problems. So, If you need official documentation, follow the
catalog  values. 
If you want to put up real antennas, just do it, but do it
right,  no corner 
cutting or compromises in materials.  Just my  opinion. 
 
    Perhaps you should have continued biting your  tongue.
The aforementioned 
anecdotal observations are interesting but have no  basis in
fact or 
engineering practice. Sure, hams overload towers and, sure,
most of them stay up but 
that doesn't mean that they are safe and reliable
installations. 
 
    Ignore the LXC Prime Directive to "DO what the
manufacturer says" at 
your potential peril. 
 
Cheers,
Steve     K7LXC


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