Technique I have used successfully is the clamp just above the center of
gravity keep it bottom heavy going up, and with a basketball hoop (without the
net), feed the mast up through the hoop which is mounted to the top of the gin
pole(separate clamp that secures the hoop to the top of gin pole) to keep the
mast reasonably vertical and controlled and place into the top of the tower.
The clamp is used primarily to keep the rope from slipping up the mast and
provides a nice stop for the mast as it goes into the tower. All this assumes
the gin pole is greater than 1/2 the length of the mast.
Standard gin poles typically come with a 12 ft. inch heavy wall aluminum tube,
for a mast this yours, I would change that to 15 ft or so. Also best to have a
removable pulley head (someone makes those at a reasonable price) that you can
mount on the end of either the 12 or longer alum. tube for the gin pole as
necessary. The gin pole bracket that attaches to the tower leg of course has
to match the OD of the gin pole to work properly. With my 15 ft. long gin pole,
I have easily installed 24 ft. masts that are quite heavy. To save the human
energy side, I use an electric winch for all my heavy lifting.
Regards,
Mark, K1RX
On Friday, November 8, 2013 9:22 AM, "john@kk9a.com" <john@kk9a.com> wrote:
200 pounds is no load at all for a crane. I install a muffler clamp on
the mast just to ensure that it does not slip off the end. If you tie near
the top you'll have to climb the mast to disconnect.
John KK9A
To: <towertalk@contesting.com>
Subject: Re: [TowerTalk] rigging for lifting a heavy mast?
From: "Earl Morse" <kz8e@wt.net>
Date: Fri, 8 Nov 2013 05:21:34 -0800
List-post: <towertalk@contesting.com">mailto:towertalk@contesting.com>
>I'm going to be installing a 20' heavy steel mast in my tower (a Trylon 72'
>self-supporting tower). I will be renting a crane to lift the mast and drop
>it from above. What >kind of rigging do I use on the mast so it can be
lifted
>up vertically, without the sling slipping up off the top of the mast?
I have always used a clove hitch with an extra turn (
http://www.realknots.com/knots/hitches.htm#mwvsl ) which I tie just above
center of gravity on the mast to prevent tipping on the way up. Never
knew it
was called a rolling or magnus hitch. To ensure that this doesn't slide I
usually put a muffler clamp on the pipe for the knot to pull against. A
22 ft.
mast is just about at the limit of my gin pole so sometimes I tie a tag line
(loop) from the lifting line to the top of the mast in order to prevent
tipping.
Tie it good. If I remember right that mast weighed nearly 200 lbs and was
quite a pull.
Earl
N8SS
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