Cheat et al,
A year ago we were hoisting assembled sections of AB105 into place at NR4M
using a special gin pole that Paul K4JA had crafted. Working at the 80 foot
level, a little too much lateral pull was placed on the hoisted tower
section by the ground crew to keep it from getting hung up on the existing
tower. The gin pole had been attached to the top foot and a half of the top
existing vertical member. That vertical member folded over just below the
bottom of the gin pole. Fortunately no-one was seriously hurt and we've
since gone to building 105 piece by piece or assembling large sections and
craning them into place.
Since then we've rather wondered if the gin pole had been attached to the
next vertical member down (that had diagonals attached) whether the diagonal
would have proved enough additional support to keep it from folding over.
The reason for attaching as we did was to get the most use of the 10 feet of
When you consider using a gin pole, due consideration must be given not only
to how strong the pole itself is, but to how strong the attachment point on
the tower is. Obviously the forces at play when using a gin pole increase as
the length of the pole is increased, especially as the lateral forces on the
gin pole increase.
For as easy as it is to build 25, 45 and 55 tower using proper gin poles, I
don't understand why one would want to complicate things by assembling pairs
of sections and working with the increased weight and need for additional
Be careful up there!
73de Larry K7SV
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