Hello,
Regarding the ability of screw in anchors to hold - An eighty foot
pine tree fell across one set of guys on my 130 foot tower in
hurricane Isabel. The tower was guyed by three sets of 4 levels of
Phylistran (4000 lb) guys, each set to a single screw in
anchor. Three of the guys in one set were broken by the tree. (Yes,
the tower and ant. were turned in to a bunch of steel and aluminum
pretzels.) The screw in anchor for that set of guys looked like it
hadn't budged. The soil has a lot of clay in it and the tower had
been up for 4 years.
Please consider the above as one data point in making your decision
as YMMV always applies.
At 08:38 AM 1/16/2006, Pete Smith wrote:
>Not to mention that you do not have the typical ham single-point
>failure risk , with all the guys in one plane attached to the same anchor!
>
>73, Pete
>
>At 08:19 AM 1/16/2006, Dennis OConnor wrote:
> > I have two towers, 130' lightly loaded and 150' with LARGE
> antenna loads - way, way beyond Rohns data for 25G... They are
> installed with screw anchors into sandy ground... They have been up
> more than ten years without any incident or evidence of failure...
> Storms with recorded gusts to 89 mph have happened over those
> years... In Michigan we have freeze thaw cycles up the bungees...
> >
> >So why does it work for this clueless ham?
> >Well, ol clueless here designed and installed it so that there is
> a separate anchor for every 60 feet of tower, i.e. only two guys
> per anchor... And the steepest guy angle to any anchor is 45
> degrees, while it's lower mate is roughly 30 degrees... My
> suspicion is that the tower sections will bow enough to gyrate and
> twist the tower down before the guy anchors will pull
> out... Limiting the load to each screw by keeping the guy wire
> angle low, is the key in my book...
> >
> >denny
> >
> >
> >
> >
> >
> >---------------------------------
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73,
Mike, K4GMH
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