In a message dated 99-06-09 22:49:51 EDT, firstname.lastname@example.org writes:
> I was wondering.........................I am re-vamping my main antenna. The
> new support is 40 feet of Wacky Shack TV mast which is bolted directly to
> 20 foot 4X4 which is up against the house. This allows all of my radials to
> be elevated with most of them at the roof level. Anyway, I was wondering if
> 3/32" double braided dacron/polyesther rope would be strong enough to hold
> up the TV mast? I plan on guying it at the top and then half way down from
> the top, or, the middle of the mast at the 20 foot level which is 20 feet
> over the roof.
> All this is doing is acting like a wire support for my various wire
> antennas so the wind load on this should not be all that great. So will
> 3/32" be okay?
First find out the square footage of your exposed structure and antenna
that's supported by the dacron rope. Next multiply that by the wind pressure;
i.e. 20.0 psf @ 70 MPH, 30 psf @ 87 MPH. (I don't know what county you're in.
You can look up your county windspeed rating at http://www.championradio.com;
look under Tech Notes.) This'll give you the load on the ropes.
3/32 dacron rope, according to the manufacturer, is rated at 260 pounds
breaking strength and half that for working strength. Since all other rope
and wire rope manufacturers use 10 or 20% of the breaking strength for the
working load, I would rate it lower - say 65 pounds (approximately 25%). If
your load is more than 65#, you might want to use bigger rope, double it up
or just cross your fingers.
Cheers, Steve K7LXC
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