[TowerTalk] Thoughts on towers suitable for my difficult location?

[KS4TL]

Hmm, I didn't know custom plans were available so inexpensively. Thank you.

I'll also give the vertical idea some serious consideration - certainly
I've been happy with the performance of my 40 meter vertical.


> 
> You probably want to have an expert.  It need not cost a fortune.  If
> you're going with US Tower, for instance, they will provide custom plans
> for reasonable money.  I paid 300 for mine for the Sonoran dessert. 
It was
> "similar to" but not identical to the "ordinary" plan that you can
probably
> get on-line.
> 
> I have sandy soil as well, of varying "silti-ness" and in my case, the
> answer was to make the hole 2 feet deeper.  Dirt, even crappy sand, is
> amazing stuff, really.  Get enough of it and you can hold up a lot.
> 
> You probably do want to look at shorter towers because of the wind speed.
> But, you may be able to still do, say, 65 feet, which is a little bit of a
> magic number for HF.
> 
> The other thing I would do in your situation is read up on "Team
> Vertical".  Phased verticals (classic or vertical dipoles) may work as
well
> or better in your location than a tower anyway.  You're basically in a
salt
> marsh (or its near equivalent) and have sea water in many significant
> directions.
> 
> What are your interests?  If I were doing Honor Roll or DX Marathon from
> your location, a couple of four squares for 17 and 20 meters may be enough
> and could certainly be put up while you are working on the tower problem.
> Even a phased pair (pointed NE/SW) could be interesting for you, at least
> for a while.
> 
> 
> Larry WO7R
> 
> 
> On Wed, Oct 23, 2013 at 9:38 AM, Your Name <ks4tl at rodentranch.com> wrote:
> 
> > I am trying to determine if it would be practical to safely install a 40
> > to 50 foot free-standing or bracketed (not guyed) tower in my location.
> > I would like to hear from anyone who has erected a tower in a
similar area.
> >
> > My location is Chincoteague Island, Virginia, Zip Code 23336. If I am
> > reading the “three second gust speed” maps correctly, this location is
> > in a 120 mph area on the Exposure “C” maps. However, the location is
> > also about a quarter-mile from open water (an inlet off the Chesapeake
> > Bay), so it is possible that it should be considered Exposure “D”. The
> > location is flat and barely above sea level, with no significant
> > features to obstruct wind.
> >
> > The soil quality is about as poor as possible from a support standpoint.
> > It is silty sand, and during the course of a year varies from dry/loose
> > to completely waterlogged. It is also mildly salt-contaminated(from
> > seawater flooding in 2012), and so rather corrosive. The ground water
> > table is high - holes deeper than 3-4 feet tend to fill with saltwater.
> >
> > One good thing: winters are relatively mild, frost depths never exceed
> > an inch or so. Ice storms are rare. Icing would not be expected to
> > exceed 1/4 - 1/2 inch at most, and ice storms have not been known to
> > occur at the same time as high winds.
> >
> > One final feature of the site: it is subject to tidal flooding during
> > severe tropical storms and nor’easters. Every 2 or 3 years, the base of
> > any tower at this site will be immersed for several hours in seawater,
> > to a height of up to 4 feet. (Most houses here, if you are wondering,
> > are elevated on pilings or perimeter walls.)
> >
> > Guying of the tower is absolutely not possible. Bracketing to my
> > residence (modern construction, concrete walls from the ground to four
> > feet, frame above four feet) may be possible.
> >
> > The total wind load of all equipment would be about 10 square feet.
> > I would install either a K4KIO Hex-Beam, a 2-element Steppir Yagi, or a
> > small tribander (Force 12 C-3S or similar) on the shortest practical
> > mast at the top of the tower.  All of these have rated wind loads below
> > 6 square feet. A medium-sized rotator (Yaesu G-800 SA or equivalent)
> > would be used. I would probably also attach 1-2 fixed, omnidirectional
> > VHF/UHF antennas to the tower.
> >
> > My initial idea is to simply overengineer - select a tower rated for 120
> > mph at *double* my planned windload, and go up a step or two on the
> > usual foundation size. I'm also inclining toward an aluminium, rather
> > than steel, tower due to the saltwater corrosion issue.
> >
> > Any thoughts would be much appreciated. I might end up turning to a
> > Professional Engineer for final planning, but I'd like to check to see
> > if this is even remotely feasible before I incur that expense.
> >
> > Thanks,
> >
> > Jeff / KS4TL
> >
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>