Scott, WA4DOS wrote:
<<I'm planning on putting up six sections of Rohn 25g. Someone
locally suggested using 5/16th inch Dacron Rope(UV Resistant) for 2
sets of guys on each leg...snip...any problems with doing this??>>
Hi Scott. Sounds like a nice, compact tower setup. You definitely
want to stay away from using rope as permanent guys. The forces that
can build up on your tower are surprising in bad weather. To answer
your question, here are some problems with rope:
1) Limited ultimate strength. As Steve already pointed out, this
rope is just not strong enough to resist the loads from wind. Even if
you oversize the rope to compensate, there are still problems. When
you tie a knot in your rope, at the ends, the tensile strength is
weaker still. It varies from knot to knot, but you usually cut its
breaking strength down 10-30 percent.
2) Too 'stretchy'. Again, let me confirm what Steve mentioned. This
is a concept that is a little harder to accept, but there is more to
guying than ultimate strength. Guy cables must not be too elastic or
they cannot stabilize the tower properly. Rope is far stretchier
(more elastic) than steel or aramid fiber.
3) Fragile. Ropes are easily cut by abrasion from tree limbs or
vandals. Brush fires will take 'em out, too.
4) Climbing stability. If you don't climb a lot (like me), this can
be important. A properly tensioned set of steel guys makes your tower
feel remarkably more stable when you climb it, due mostly to #2
above. When you feel safer, you are less nervous and you can
concentrate on your tower work and climbing gear more effectively.
5) "Do it right, sleep at night". This especially comes true when
the weather turns sour.
Good luck, Scott
--...MARK_N1LO...--
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