All tower owners should regularly inspect their complete tower system – guys, guy anchors, guy wires, tower base, section bolts, turnbuckles, etc – the complete tower system. Before I climb, I visually check all I can see. When I climb, I check section bolts. And about once a year, I check guy tension and adjust as needed.
|10 Feb 2021||NW Guy||NE Guy||S Guy|
This process led to me emailing Tim W3YQ to ask his thoughts. Here is the reply:
Well, here’s my thoughts. Plumb is much more important than guy wire tension – within reason. To have a tower in plumb, the whole structure is in compression. It won’t fail. Just like a pencil – you can’t smash it with a downward force, but you can snap it by bending it in the middle.
I know of only two ways to plumb a tower. The first, best, and easiest is to set up two transits; 90 degrees apart. Sight both transits to the bottom of the tower then move up to the first guy level. Get the tower straight up to that point. I usually use the width of a Rohn tower leg as my “good enough” standard. If the tower’s way out of plumb, you might have to mess with the other two sets of guy wires simultaneously. Sometimes it’s really hard to pull that first guy wire set in when the rest of the tower is fighting you. Once the lowest set of guys is done, move up to the next set.
The tension of the three guy wires of any level will (almost) never be equal. The only time that would occur is if you were on a perfectly flat plane and your guy anchor points are exactly on the money. Theoretical but not practical. Someone who adjusts all three guy wires to equal tension almost certainly have a crocked tower. Don’t worry about guy tension. Go for plumb. Use the tension gauge to help you get things set “close” to the suggested tensions. Err on the side of loose instead of tight. That 10% rule is a guideline and it’s purpose is to prevent the guy wires from galloping. They’ll do that in the wind if they’re much too loose. Loose guy wires, again within reason, exert less force on the structure. Yes, when you climb, there will be a little more movement with loose guy wires, but the tower is not going to fall over. Too tight, on the other hand, is exerting an extreme downward force on the tower. True that if you’re perfectly in plumb it won’t collapse, but why go there. So just use your Loos gauge as a guide. Never go above the 10% value on any guy wire, but try to get close to that value on the one that needs the most tension. Then adjust the other two guy wires for plumb and not tension. I usually check the tension of all three and I generally find that they’re way off from each other. That’s OK.
The second method: It IS possible to plumb by attaching a small rope at each guy level, one at a time. Center it in tower, hang it down through the middle of the tower, and attach a weight at the bottom. Then stick a bucket of water for the weight to rest in. I guess you call that a plumb bob. The water keeps the weighted rope from swinging. It’s kind of a PITA, but it works.
So, this led to me purchasing a transit and acquiring another to be able to properly do “Method One” above. Once all the components arrive, I’ll post an update on the project.