Three years ago I put up a 15 year old used triex wt51 crankup tower and
according to the original manual I needed a 3' x 3' x 6' (2 yards of concrete)
foundation so that's what I put in. Two years ago a big storm blew through
here and folded the tower over at the middle section. Pretty obvious that 2
yds of concrete was plenty for that tower!
However, I think its got to make some difference where you're digging the
hole. I'm out here in the Black Hillls of South Dakota and the only way I
could dig the hole was with a jack hammer.... that's pretty solid ground
surrounding my concrete. If I'd have been in Nebraska digging through 6' of
soft topsoil maybe the 2 yds of concrete wouldn't have held. So I suppose the
specs are written for worst case.
Gary Slagel
Hot Springs, SD
N0SXX
http://marina.fortunecity.com/sanpedro/351
--- On Fri, 5/13/11, WA8JXM <wa8jxm@gmail.com> wrote:
From: WA8JXM <wa8jxm@gmail.com>
Subject: [TowerTalk] concrete bases for freestanding towers
To: towertalk@contesting.com
Date: Friday, May 13, 2011, 6:18 AM
Many years ago I had a 64' freestanding tower with a 3el triband beam (TA-33)
on it. The base was only 2 cu yards of concrete. As far as I remember, that
was all the manufacturer (Heights) recommended at the time.
Now when I look at anyone's recommendations, the base requirements are much
larger. Rohn (and others) recommends 3 cu yards even for a 40' BX tower. I
had used only 1 cu yard for a freestanding 40' tower.
Is my memory faulty, or have the recommended bases grown over the years? Were
the old recommendations inadequate, or has everyone grown super conservative
over the years? "If one yard is adequate, three will be better, so let's use
five yards"???
As one ham commented on the air yesterday, the only failures he has ever heard
of were in the tower itself, not the base falling over.
Ken
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