[TowerTalk] raising tall structures

[alsopb]

Good question Brian.  Maybe you should ask the group.
Possibly the "falling derrick" technique?

73,  Tom N4KG

On Sat, 05 May 2001 20:12:46 +0000 alsopb <alsopb@gloryroad.net>
writes:
> Just for curiosity, how in the old days of sailing ships did they get
> those 100' + masts of solid wood with two foot diameters vertical--
> especially the first one?  I suppose it is easy in a shipyard. 
> However, consider this:
> 
> I saw a recent documentary where they still use sailing ships in 
> parts
> of the Pacific near Indonesia.  On one such trip, the main mast
> failed.  The captain went ashore somewhere, bought a tree, had it
> shaped into a suitable mast and re-installed it.  I don't believe he
> had another tall mast on the ship.
> 
> How did he do it?  They didn't say.  Apparently, this is something
> which isn't too unusual, given that the captain wasn't any kind of
> mechanical wiz.
> 
> 73 de Brian/K3KO
> 
> n4kg@juno.com wrote:
> > 
> > Picture this:
> > 
> > You have 90 ft of R25 assembled and anchored at the base.
> > You lift the top 5 ft.  Imagine a horizontal "rope" pulling on the 
> top
> > towards the base.  The tower weighs 300 to 400 lbs depending
> > on the weight of the lights, wires, guys etc.  To hold the tower
> > 5 ft up will require a rope tension of ( 90 / 5 ) X 200 lbs = 3600 
> lbs.
> > The BASE must also be able to withstand this *horizontal* force,
> > or more.
> >

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