[UK-CONTEST] Pulleys and rope

[G3RIR]

I may be called a pedant for this but 

the method described and used by most groups is a FALLING DERRICK not a GIN
POLE.

A gin pole is one temporarily fixed to the top of a mast or tower or other
structure to lift other sections vertically.

We (DeMontfort University ARS) use marine grade pre-stretched polyester.
Polyprop even if used once or twice a year degrades with age even if not in
direct sunlight. Jimmy Green Marine Chandlery in Beer Devon has a good
website and mail order.

As for pulleys and blocks the same source has a multitude of choice. Cost
should not be an issue when safety matters and in any case you don't need
many even for a full open or multi-multi station. 

Neil, G3RIR



-----Original Message-----
From: uk-contest-bounces at contesting.com
[mailto:uk-contest-bounces at contesting.com] On Behalf Of Chris Tran ZL1CT
Sent: 09 July 2007 22:37
To: steve at m0bpq.com; uk-contest at contesting.com
Subject: Re: [UK-CONTEST] Pulleys and rope

Hi Steve

As Adrian suggests, you will probably need a 'double-run' i.e. 2 pulleys at 
the top and 2 at the bottom. There are several things to watch out for 
though - for example, marine pulleys are expensive and often have a 'vee' on

one side which is designed to trap the rope when required - this is an 
undesirable feature for antenna raising/lowering. Also, it is sometimes 
difficult to obtain a pulley block which has an eyelet or hook at  both 
ends, which is what you will need for one of the pulleys.

For example, 2 x 20' steel scaffold poles with a 20m 3ele monoband yagi on 
top are easily raised by one person using a 20' steel scaffold pole as the 
gin pole, using 2 pulleys at the top and 2 at the bottom, with 10mm rope. 
However it does take quite a time setting up the side guy tension etc. and 
raising/lowering several times without the antenna of course.

73
Chris
GM3WOJ / ZL1CT 

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