NEVER install a Yagi without rope inside the elements.
I followed Force 12's advice and installed a 10-15 meter dual band Yagi with rope. It moaned, and then about a year or two later an element cracked and fell right off in a mild breeze!
I also knew a CBer who has a 100 foot aluminum tower, and the tower or his antenna vibrated in the wind. After about a year or two the top of the tower just fell right off. You could see where the legs got hard and cracked from the vibration.
### Several folks here in town have had rope inside yagi els for more than 20 years, with zero problems. I never did myself, but noticed that IF my hygain and wilson yagi's were just at the correct angle to the wind [ light breeze], they would vibrate badly..and always about 5' out from the boom.[ both sides of the boom] My HB yagi's did the same thing. Unless u dampen down the vibrations, they will fall apart from severe metal fatigue. They would osc up/down a good 5" in total, 2.5" above and below.
BTW, F-12 says not to install rope inside their ele. Why would you? The typ F-12 ele goes like 9/8, 8/8, 7/8, 6/8, 5/8,4/8,3/8" The whole idea is to get rid of 'vortex shredding' ....and the way that F-12 does it, is to keep dropping the OD of each section down by 1/8". They also do not use any swages anywhere. I have several F-12 yagi's from 80-15m. None of em vibrate, and none have rope in the else. By not useing swedges, you get a more uniform tapering of the element, and the differing diams will kill any osc's. It's a slick design.
I don't know of anybody who has ever used rope inside a F-12 yagi. Is this something that is recent ? Mine are all 5-8 years old.