Call Search
     

New to Ham Radio?
My Profile

Community
Articles
Forums
News
Reviews
Friends Remembered
Strays
Survey Question

Operating
Contesting
DX Cluster Spots
Propagation

Resources
Calendar
Classifieds
Ham Exams
Ham Links
List Archives
News Articles
Product Reviews
QSL Managers

Site Info
eHam Help (FAQ)
Support the site
The eHam Team
Advertising Info
Vision Statement
About eHam.net

donate to eham
   Home   Help Search  
Pages: [1]   Go Down
  Print  
Author Topic: Which Guy Rope?  (Read 2272 times)
M0NER
Member

Posts: 2




Ignore
« on: March 21, 2007, 01:04:24 PM »

I live in an area that has max winds of roughly 80mph.
My mast is 2inch od aluminium standing 8 mtrs high.
I will fix for guy ropes at the 7mtr point.
I intend to use braided nylon white cord for the guys.
3mm diameter cord 250kg max load
4mm diameter cord 380kg max load
6mm diameter cord 620kg max load
Any ideas as to which cord would be most suited to the job. Price is not a concern but I would like to use the thinner stuff to make the visual impact of the guys as small as possible assuming the max load will be up to the strain.

Thanks for any advice

Alan
Logged
WB2WIK
Member

Posts: 21754




Ignore
« Reply #1 on: March 21, 2007, 01:21:03 PM »

I wouldn't use the "nylon white cord," at all.  I've used miles of that, and it's not as good as this stuff:

http://www.synthetictextilesinc.com/supportham.html

The 5/16" (8mm) double braided Dacron rope is superb for this job: It stretches less than nylon, is more tolerant of UV (ultraviolet radiation), and its dark color blends into the background much better than "white," which is easy to see for a long distance -- even at night.  The black cord disappears completely at dusk, and even in broad daylight isn't very visible since it reflects almost nothing.

For your application (to guy an antenna support mast), you'll need to use turnbuckles also, and re-tension them now and then.  Simply stretching the rope and tying it won't do the job.

WB2WIK/6
Logged
N3OX
Member

Posts: 8910


WWW

Ignore
« Reply #2 on: March 21, 2007, 02:12:12 PM »

According to the formula here:

http://k7nv.com/notebook/topics/windload.html

I calculate about 85 lb total windload on a 2" mast 8m tall... (4.37 sq feet)

Assuming that 85lb acts at the center of the mast, a guy at the top might be called on to provide a horizontal force of about half that to keep the mast from falling over (the torque about the base has to be equal).. actually at the 7m point it would be 4/7ths the windload... or about 50lb horizontal force.  

If the guys come away at a 60 degree angle, then the tension in the guy is twice that... so about 100lb tension, or 45kg.  You'd want to add to that some static tension that just stretches the rope a bit... maybe another 20kg?

I'd suggest comparing this total of 65kg to the *rated working load* of the cord if you have that information available.  You might be able to get away with the thinnest stuff you've got, but you'll also need to consider stretch... the thinner stuff will have more stretch than the thicker.

I agree 100% with Steve about the color.  8mm black rope has less visual impact than 2mm bright white as far as I'm concerned.

I'd go with the biggest stuff for peace of mind, myself.

Here's my antenna installation.  All the rope here is 5/16" double braided black dacron:

http://n3ox.net/projects/sixtyvert/antennafarm_lg.jpg

Here's another one:

http://n3ox.net/projects/sixtyvert/tallshot_lg.jpg

I added another set of guys to this thing and used ~1.5mm white cord originally because I had it on hand and wanted to operate a contest in some very windy condx and the visual effect was quite jarring... they were really visible in the sun and much easier to see at night ... I replaced the top set with 1.8mm black cord and it's much better.

73,
Dan
Logged

73,
Dan
http://www.n3ox.net

Monkey/silicon cyborg, beeping at rocks since 1995.
N6AJR
Member

Posts: 9930




Ignore
« Reply #3 on: March 21, 2007, 02:26:19 PM »

I use the double dacron stuff (5/16) from hro.  the inside rope is white nylon  or something and the outer cover of black dacron protects it from the sun etc.

I use a minimum of 2 sets of 3 guys on most anything I guy, as a minimum, it keeps the mast from bowing in the middle.
Logged
KG6OMK
Member

Posts: 107




Ignore
« Reply #4 on: March 21, 2007, 02:57:23 PM »

I think you should be as concerned about stretch as about the strength of the rope.  Nylon is only slightly less stretchy than bungee cords.  Nylon is usful when you need some kind of shock absorber.  Rock climbers use it to catch a fall and sailors use nylon for anchor lines but never for rigging.

Polyester (a.k.a "Dacron") has much less stretch.

After Polyester you can buy exotic line like "spectra" that has properties not unlike wire rope.
Logged
WB2WIK
Member

Posts: 21754




Ignore
« Reply #5 on: March 21, 2007, 03:03:26 PM »

The Dacron rope from HRO is made by Synthetic Textiles, the company I provided the link for earlier.

The inner white stuff is also Dacron.  The outer black woven stuff is Dacron, too.  It's all Dacron.

You have to melt the ends after cutting it, or use a hot knife to cut it -- that melts it as it cuts, so the ends are sealed when you're done.

It's great stuff.  I wouldn't use any kind of nylon.

WB2WIK/6
Logged
ONAIR
Member

Posts: 3536




Ignore
« Reply #6 on: March 21, 2007, 05:10:45 PM »

    I've used heavy duty fishing line that I had laying around in the closet with good results.
Logged
WB6BYU
Member

Posts: 17192




Ignore
« Reply #7 on: March 21, 2007, 06:36:17 PM »

WB2WIK wrote:
> You have to melt the ends after cutting it, or use a hot knife to cut it

A piece of #12 wire chucked in the end of your soldering gun in place
of the regular element, with part of it flattened with a hammer, makes
a handy hot knife for such things.
Logged
KC0SHZ
Member

Posts: 372




Ignore
« Reply #8 on: March 22, 2007, 07:21:49 AM »

What about parachute cord?
Logged
WB2WIK
Member

Posts: 21754




Ignore
« Reply #9 on: March 22, 2007, 08:21:14 AM »

>RE: Which Guy Rope?       Reply
by KC0SHZ on March 22, 2007    Mail this to a friend!
What about parachute cord?<

::The guy whose parachute you cut it from will be very unhappy next jump.

Seriously, most parachute cord I've worked with isn't nearly as good as the Synthethic Textiles double braided Dacron.  This stuff is actually sold as "ham radio antenna rope" (no kidding, it's in the manufacturer's catalog and on their website exactly that way) because we, a bunch of hams, convinced them to make this rope this way specifically for supporting antennas, masts and towers.  Synthetic Textiles was a fairly new company in Ventura, CA and woman-owned.  The women were very sharp about rope and about business, but knew nothing about ham radio.

So, several of us got together and visited them in 1989 a few months before Field Day to see if they had rope that would be really useful for us.  They made lots of parachute cord and all kinds of stuff, but nothing suitable for us: We wanted weatherproof, waterproof, light weight, UV-resistant, abrasion-resistant, non-stretch, very strong rope that wouldn't unwind, untwist, or tangle.

They took some time and made some sample rope.  We loved it.  That rope became a new family of products they decided to call "ham radio antenna rope" and it's widely distributed by HRO, AES, Davis RF, The Wireman, Cable X-Perts and lots of amateur radio retailers.

They have since moved to Anaheim and are a bigger company now, but they still make great "ham radio antenna rope," and it's all I'd use for this.

WB2WIK/6
 
Logged
N3OX
Member

Posts: 8910


WWW

Ignore
« Reply #10 on: March 22, 2007, 09:18:17 AM »

"they still make great "ham radio antenna rope," and it's all I'd use for this."

I have to agree.  You can use what you want, but the black dacron rope that Steve's talking about is the best I've ever used and it's all I'm going to use from now on.

The Wireman didn't have any really small stuff, below 3/32".  I don't know if the company Steve mentioned makes it.  

If you're looking for very tiny black dacron for stealth magnet wire antennas or, as I was, guy rope for the very tip of a low-wind-load structure, go look for kite string.  Kite Studio carries several sizes of black dacron kite string; I got the 50lb. test stuff (about 1/32") and it was too weak for my application but would be a good match for a magnet wire stealth antenna.  I got the 150lb test stuff and that's perfect for what I'm doing... this stuff is solid black dacron something like 1/16"

So I've got four sizes of black dacron cord in my stock right now, though I've used a lot of the 5/16" already.

73,
Dan
Logged

73,
Dan
http://www.n3ox.net

Monkey/silicon cyborg, beeping at rocks since 1995.
EXWA2SWA
Member

Posts: 158




Ignore
« Reply #11 on: March 22, 2007, 10:46:03 AM »

I concur on black double-braided dacron - mine is 3/32". Excellent stuff. Since my 6BTV is ground mounted, and I can reach the anchor ends of the guys easily, I opted for taut-line hitches instead of turnbuckles. It's a simple knot to learn, it won't slip and it is easy to adjust and, oh yeah, it won't rust!
73,
Jim NS5M  
Logged
N3OX
Member

Posts: 8910


WWW

Ignore
« Reply #12 on: March 22, 2007, 12:21:11 PM »

I use taut line hitches too... actually I added an extra inside loop...
Logged

73,
Dan
http://www.n3ox.net

Monkey/silicon cyborg, beeping at rocks since 1995.
M0NER
Member

Posts: 2




Ignore
« Reply #13 on: March 22, 2007, 01:47:23 PM »

Well after some searching on the net i've managed to track a 62mtr roll of Dacron kevlar from Radioworld for £22.
I had never heard of this stuff until I posted nobody here in the uk that I know seems to use it. Most people dont like to use the wire rope but have not found a suitable alternative.
Thanks for all the advice

Alan M0NER
Logged
KC8RPD
Member

Posts: 134




Ignore
« Reply #14 on: March 23, 2007, 12:17:10 PM »

Don't use nylon; it deteriorates too rapidly and has too much stretch.
Instead, use double-braid parallel core dacron (New England Ropes Sta-SetX), available from any good marine supplier, example West Marine.  They'll also have the turnbuckles you need as well as lots of other items of use when rigging.

Rich
Logged
Pages: [1]   Go Up
  Print  
 
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.11 | SMF © 2006-2009, Simple Machines LLC Valid XHTML 1.0! Valid CSS!