[TowerTalk] Fall Zones

[Bob Shohet, KQ2M]

I don’t know how long is required to crank down at 89’ crank-up at full extension but I would suspect that it is at least 90 seconds.

At this qth, when a Tornado or macroburst/microburst winds are approaching, I get about 30 seconds warning from the oncoming “roar” of wind crashing through the trees.  The noise is loud, distinct and unmistakable.  If at that exact moment I started to crankdown an 89’ tower, I doubt that it would have been lowered enough by the time the winds arrived to make it the rest of the way safely.  If it took me a minute or two to get to the station to lower the tower, I’m sure that it would be already too late.  That’s probably what happened with the guy with the tall tower, anemometer and winch.

The other issue with such violent winds is that they are usually hurling debris as they come in.  All it would take is one solid branch or piece of something wedging into the tower at a strategic spot to stop the winch dead in its tracks.  Game over for the tower.  BTW, this is one reason why Tornados are so dangerous – often significant damage is caused to objects  by debris picked up and hurled somewhere else outside of the funnel.


Bob KQ2M


From: Wilson Lamb 
Sent: Tuesday, July 09, 2019 9:28 AM
To: undefined 
Subject: [TowerTalk] Fall Zones

I had to laugh when I saw this in a post this morning:  

" The argument is based on the assumption that the tower would be cranked down during a forecast of extreme weather such s a hurricane/tropical storm."

When I went to interview a car towing  guy for potentially using his rollback wrecker to move an 89' crankup for a friend, I asked if he had ever done it before.
Rather than answer, he said "Look around the corner of the building."  Sure enough, there lay the base section of a big crankup.
His explanation was "...guy had a tall tower with an anemometer to control a winch to lower it if a high wind came."
You know the rest; wind did, anemometer didn't, winch didn't, tower fell.
I don't know if the system failed or the wind came too quickly, but I think microbursts can come quite suddenly, even if the lowering system actually works.
Bottom line:  He was given the job and his 19' rollback never even grunted.  The 20 mile trip and unloading were non events.  Four hours, $300.
WL