[UK-CONTEST] High Winds...Rope ?

[Bob Henderson]

Hi Adrian

You say your biggest problem will be getting your towers up or down in high 
winds.  I assume you are talking about crank-up towers in that case?

The first part of the above problem is easy to answer.  You never attempt to 
crank a tower up in high winds!  The answer to the second part of this, is 
that when you have crank-up towers you need to take steps to be aware when 
high winds are likely.  You then crank down your towers in advance.  If you 
get caught out and your towers are up while high winds are developing and 
the sections become locked together due to wind pressure then you will need 
the assistance of a second person if you are to stand a chance of retracting 
the towers.

Now to the issue of guying.

You should understand that crank-up towers are mostly NOT designed to be 
guyed in the way a fixed tower would be.  The accumulated tensions in the 
guy system translate into a downward force on the tower itself for which it 
is not designed.  Ignorring wind, this force is a dead weight headload, all 
of which would have to be supported on your tower cables.  This is not a 
great idea, as it substantially reduces the usable headload of the tower. 
That said, the attachment of low tension guys for the purposes of 
stabilisation in modest wind conditions is of benefit and this for two 
reasons.

1. These will stop your towers from leaning uncomfortably and looking untidy 
in modest winds.

2. They provide a means by which a second person can assist you in 
retracting a jammed tower before the winds get high enough to cause serious 
damage.

I have used the same P80HD for 12 years now and it has always been heavily 
(over)loaded.  Currently it supports a F12 C31XR, a Cushcraft XM240, a 5 ele 
6m yagi  and an 80m delta loop, all on a very heavy 20ft chrome molly mast. 
All the above apart from the delta loop are rotated by an M2 Orion rotator. 
I use 10mm polypropelene rope to add stability to the system, providing the 
benefits detailed in 1 & 2 above.  If it looks like it's going to be 
dangerously windy I retract the tower to about 45-50ft.

Yes the poly rope stretches.  That's ok for this purpose.  It's also not UV 
stable over long periods.  I have to change mine every two years here but we 
see more sun than you do.

I hope this helps you with your planning.

73

Bob, 5B4AGN


----- Original Message ----- 
From: "Adrian Rees" <rees.a at btconnect.com>
To: <uk-contest at contesting.com>
Sent: Friday, January 12, 2007 9:48 AM
Subject: [UK-CONTEST] High Winds...Rope ?


> Hi all
> Well with the high winds we've been experiencing (my home WX Station tells 
> me gusts up to 91MPH) I've been thinking about what type of rope I'll need 
> to use to guy my towers.
> Steel or Stainless Steel would (I guess) be the strongest, but that has 
> the problem of Resonance (unless of course you break up the lengths with 
> insulators).
>
> Anyway, what suggestions does the list have for guy rope ?
>
> I have been looking at Phillystran, but wonder if a cheaper-just-as-good 
> version exists in the UK ? If so who supplies it ?
>
> As my QTH is on an exposed hill, its been pointed out that my biggest 
> problem will not be when the Towers are up or down. The problem will be 
> getting them up or down in high winds.
>
> Adrian MW1LCR
>
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