[UK-CONTEST] Mastrant ropes - Caution?

[UKCONTEST]

I had a very similar incident with my M100 tower.

The tower was guyed with the guy ropes as provided by Versatower 
(plastic coated steel rope) and installed as per the instructions (guy 
radius & positioning etc).

During a particularly bad storm 2 years ago, the second to top section 
(80 foot section) buckled and folded over nearly 180 degrees. (From what 
I gather the Bristol Contest Group had a very similar incident).
The wind was gusting at 90 - 95 MPH at the time (we are very high up in 
an exposed area of N.Wales).

I think this is what happened:

The wind was gusting 90 -95MPH, and set up an oscillation movement in 
the top section of the tower, whereas the top section was moving 
forwards (by the wind) and was moving backwards under guy tension.

Eventually the guy snapped (buckle broke in my case) as the wind was 
pushing it...as a result the tower carried on moving and reached a point 
where a section started to collapse, and linear momentum carried the 
section to buckle over.

In my case the upper most section was intact and the 60 - 80 foot 
section buckled over.

I still use plastic covered steel ropes with a length (1 metre) of chain 
at the ground anchor end. I use a motorised winch to raise & lower the 
tower. The chains facilitate fast connection & disconnection when 
raising & lowering the tower.

When not in use, the tower is down to its lowest point.

Please note Ian's point about lowering & raising ropes, I noticed damage 
to the ones I had when I lowered the tower. Wise to replace all of them. 
You won't get two chances with one of these towers.

Best of luck !

Adrian MW1LCR


On 26/09/2012 09:16, Kerr, Prof. K.M. wrote:
> It is only right to follow-up on earlier postings about my pursuit of a non-conductive guy rope solution over the summer.
> At the first serious test (and it was serious) I am afraid the Mastrant rope does not seem to be up to snuff. This is at least my initial impression.
> I think Don G3BJ asked a pertinent question at one point in our exchanges, regarding the performance of this rope under impulsive stresses such as wind gusts.
> Sad to say, I think the conclusion may be 'not good enough'. I got home last night to find the top section of the P80 guyed with the Mastrant rope (D12) bent right over and the yagi on top completely trashed. I have not had the chance to examine the damage in detail but it seems the top guy in the prevailing wind direction 'failed'. The turnbuckles, U bolts etc seem OK so I suspect the rope stretched to a point where it was serving no useful purpose.
> Difficult to be sure but my confidence in this stuff is now zero! I genuinely believe that the installation was otherwise well enough designed and assembled (but then I would say that, wouldn't I!)
>
> Keith GM4YXI/GM5X
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