[UK-CONTEST] Mastrant ropes - Caution?

[geoff plucknett]

Yes the Brizzle/East Cork Groups towers spectacular on Bere Island has gone
down in history! We lost two towers in a short but sharp 100 mph gale on
the Saturday morning of IOTA weekend 2006. Only lasted an hour or so. We
had two towers up at 100 feet with A3Ss and 40m beam on the top. Sitting in
Bantry Bay with no protection to the west, in came the wind and down went
the towers. One tower bent over around section 4 (of 5 + 20 foot pole). The
other bent at the top section and the entire top bent section complete with
pole and A3S flew out and landed over the steps up to the martello-type
tower we were in. We were well protected in the thick-walled stone tower.
How the flying section missed the cars and so on is pure luck.

Many of us spent the remainder of THAT weekend clearing up the carnage but
EJ2MT soldiered on regardless!

Geoff G4FKA

On 26 September 2012 19:01, UKCONTEST <ukcontest at btconnect.com> wrote:

> 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
>>
>>
>>
>>
>>
>>
>> The University of Aberdeen is a charity registered in Scotland, No
>> SC013683.
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>>
>>
>
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