[UK-CONTEST] Versatower guy rope sizes

[Alan Ibbetson]

The recent discussion about Versatower failures in high winds with "too 
much" headload has made me think I really ought to guy my heavy duty P60 
now that I have a 6 sqft 3el SteppIR beam on it.

A question for those using steel rope: what diameter and construction 
rope do you use?

The conductivity of steel rope puts me off. There are several types of 
synthetic guy but most of the older ones need expensive terminations (I 
was quoted £16.50 each by one supplier).

Has anyone used the Dyneema SK75 rope beloved by seafarers? It is 
expensive but easy to splice onto thimbles. Size for size its breaking 
strain is as good as steel, but it is more stretchy: 3 times that of 
steel. 20m of 6mm 12-strand SK75 will (reversibly) stretch at least 5cm 
with my estimate of a 200Kg pull from a 100mph wind gust, which looks OK 
compared to the fairly sloppy fit of the tower sections inside eachother.

Does anyone have any figures for how far the top of a Versatower can 
sway about in the wind before it is damaged? Could I use 4mm Dyneema at 
half the price of 6mm but with about 10cm stretch, or is that an unwise 
way to save £200?

73, Alan G3XAQ
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Alan Ibbetson
alan at g3xaq.net