[UK-CONTEST] Gin Poles

[Roger Dixon]

One trick missing from all the descriptions is how to lower the mast safely
after the event!  Steve's description of pre bending the mast for erection
is fine.  BEFORE you remove the guys from the gin pole (or was it a falling
derrick ??!!) to attach it to the guy stake, mark the position on the guy
with a piece of tape.  That way, when you reattach the guy for lowering you
achieve the same safe shaping of the mast.

Roger - G4BVY

-----Original Message-----
From: uk-contest-bounces at contesting.com
[mailto:uk-contest-bounces at contesting.com] On Behalf Of Steve Knowles
Sent: 22 June 2010 19:56
To: UK Contest Reflector
Subject: Re: [UK-CONTEST] Gin Poles


----- Original Message -----
From: <tim.trew at btinternet.com>
To: <uk-contest at contesting.com>
Sent: Tuesday, June 22, 2010 5:03 PM
Subject: Re: [UK-CONTEST] Gin Poles


> Another part of the secret is to make sure that the top of the mast goes 
> up no more slowly than the middle. We used to use this method for a box of

> 4*21 els on 70cm + splitter + preamp + relays + stacking frame on a 50' 
> mast. That weight used to make the mast bow upwards in the middle as soon 
> as we started to raise it. Once we ended up with both ends of the mast on 
> the ground, but the middle 20' up in the air - and some very bent scaffold

> poles and beams. If your aerial is heavy enough to bow the mast, you need 
> to make sure that the rope to the top guy is _slightly_ tighter than the 
> one to the middle to counter the bow ... or have a brave soul with a hard 
> hat pulling down on the back guy at the centre of the mast to keep it 
> straight - we didn't have any volunteers!
>
> 73
> Tim G8JXV

The secret is to use plenty of guy sets (four or five for a 50-footer) 
attached to the mast by plates or slip rings which are free to rotate.  The 
mast is laid out and the side and back guys tied up as usual.  The gin pole 
(or derrick, whatever) is laid out to one side, fixed very close to the 
bottom of the mast, and the guys which will raise the mast are attached to 
its end, starting with the bottom guy and working up.  As eash successive 
guy comes to be attached, the mast is deliberately bowed towards the gin 
pole by tying each guy tighter than the last.  When all the guys are on, the

gin pole is rotated into the vertical and its stabilising guys can be fixed.

For a forty-foot mast with a moderate headload, three to four feet of bow 
seems about right.  The mast should then be raised at least part of the way 
to check guys for tightness/length before lowering and attaching the 
headload.  A four-to-one block & tackle to pull on the gin pole makes for 
easy adjustment.
When the mast has been raised so that the top is roughly over the bottom the

guys are taken off the gin pole in the reverse order and tied off to their 
stake.  As each guy is tied to the stake and the mast is pulled straight the

previously removed guys will tighten up.  Multiple adjustments may be 
required to get things absolutely right.

Addiscombe ARC has used this technique for many years!  This NFD saw a 
forty-footer with a Cushcraft A4 and rotator plus a sixty-foot plain mast 
put up by a team of four in a total of well under two hours.

73
Steve
G3UFY
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